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Installation of a stage pin plug on a cable, plus history

Discussion in 'Lighting and Electrics' started by ship, Feb 23, 2004.

  1. ship

    ship Senior Team Emeritus Premium Member

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    Stage Pin, Wiring and a bit of history about them or at least as much history of it's development as I am aware of at this time:

    There are four main types/periods of stagepin/slip plug design. I will refer to it as old style Union Connector co., but Kliegl, Century, Lighting Equipment Co. And VN also made them amongst other manufacturers in similar or unique styles. Now there is two sizes of stage pin plug used the 20 amp and 60 amp, back when this plug designed there was four sizes of stage pin plug - the 10 and 30 amp types having been discontinued in use.
    The first stage pin plug was designed before ferrules and crimp on ring terminals, simply put it was a set of pins in plastic or fiber of some sort, that had slight recess pathways molded into them for feeding the wire and cover over it. Nothing like even the newer Union style plug which was a molded plastic/Bakelite material with at least some room for wiring much less terminals. The materials used were not overly strong so most of the body of the plug was bulk thickness of material for strength. Not a lot of space inside the connector for wires, space between conductors or strain relief on the main 12/3 grade S cable fitting type. The strain relief and its hole offered little grip to this type of cable once the cable was warn in and shrunk slightly and as such it was frequent that the jacket would slip out of the strain relief, much less conductor insulations would also frequently be stretched back exposing conductors to each other that with some twisting of the cable that was also easy to do could short the conductors. Conductors could short even if not stretched or the cable twisted, they could short if the jacket were cut back to far and there was moisture added to the too short a space between conductors or if the conductors heated up and flaked off also exposing conductors to a short. Also the pins of this type of connector might have been a little softer because it is more common for the heat expansion slot in the pins to be pushed together or the entire pin itself bent over.
    A further problem of this time period was there was aluminum conductor instead of copper wire available for use in the theater as a cheaper alternative to copper, and those who use it with a brass pin and screw quickly found galvanetic oxidation problems - dissimilar material problems with touching and passing a current between each other which would oxidize and cause high resistance connections. Aluminum wire since has fallen out of usage thankfully but at the time it was about almost common to find. The outer jackets were similar and you never knew if the cable was copper and rated for full load or aluminum and rated for less of a load, much less what would cause a fire for you under heavy loading.

    I expect such connectors when new came with a sort of wire cavity washer which allowed the wire to fit and be supported within the cavity and be made into a circle around the screw much similar to Bates connectors coming with ferrules. Such wire washers are not exactly the easiest thing to find on the market and as such wires were at best tinned which would work to some degree in supporting the wires under the pressure of the screw terminal onto it, given some potential problems with cold solders and overheating of the insulation over the wire causing high resistance connections and shorts between conductors. Still it was better than just inserting the bare wire alone into the screw terminal than hoping the screw head would not sever conductors, apply uneven pressure on the bulk of them or allow for a loose terminal once the conductors settled in. Stranded wire has different grades. Building wire while individual strands are a lot larger and fewer than what is on a cable. They can withstand more abrasion and twisting from the screw head, but because the strands are larger, it’s also less flexible. Cable is made with smaller strands so it will move about in general without wearing away at them. It just does not work well without support. This is all given the screws themselves did not come loose be it from strands coming loose making the tension on the screw not sufficient for it to become loose, or just the screw coming loose on its own with or without enough tension.
    In addition to issues with the wire cavity and how conductors are attached, the plug while well designed enough in becoming a industry standard two pin or three pin, layout, its strain relief cavity was far too close to the attachment point, and only designed to grip a 12/3 grade S cable. Even than it would slip. For this reason, even on the proper wire friction tape was used to bulk up the wire size to make it hold. For smaller gauges of wire, even a 12/2 grade S, there would need to be extra bulking up of the wire thickness to make it hold. Hopefully it was applied correctly or it would slip even still. 12/3 SO is almost 5/8" in dia. Try to insert a 16/3 SJ fixture wire into such a plug and you would have to make up for the difference in a 5/16" cord with something. Could be a jacket on a old cord, could be friction tape, could be almost anything that might or might not work. This plug if done to the old timer standards with trained technique can be safe and rugged to use, but without such experience passed on, can also be very unsafe to attempt to use.
    An alternative design of the original Union plug was for individual un-fiberglass sleeved asbestos fixture conductors that fed in thru individual holes in the back of the plug. This provided individual pathways for the wires with defined barriers between conductors. The asbestos wire alone was considered to be sufficient alone without any sleeving over it to protect the wires, so it was possible to feed them into the back of the plug from separate holes. Not very workable with modern cable, but it was a good idea except if the wire was braided or banded together, at which point the flexing the strands would have to bend around a sharp corner at the back of the plug that would abrase the wire’s insulation. Other than that, this was a really good plug which was probably the original concept for the single hole version since there is a lot less space in the single hole version. However due to the lack of un-sleeved conductors, such a style is not found anymore. It also has the same problems of strain reliefs not being designed for other than one style of wire - thus needing help to grip the conductors. There was at least a lot more space between terminal and strain relief. A final incarnation of this plug will have been for twofers with individual very thickly insulated wires braided together and exposed. Such things still exist no doubt 20 or 30 years later in some companies a testament to the design and the very good wire used.
    To wire this plug, you removed the insulation off about 3/4 to 7/8" of wire, than cut 1/8" off the neutral and 1/4" off the ground if there was one. Next right out of the jacket you would fold the hot and neutral at a 90° angle to the jacket, than at 3/8" and ½” bend the conductors back towards the plug’s terminals. This would make a fork shape that would fit within the wire well fairly well with only slight adjustments needed. You would than strip 1/4" to 3/8" of insulation off the wire and form it into a circle for either insertion into the wire washer or tinning. Before the wire was actually inserted into the connector a few layers of friction tape would be placed over the jacket of the plug to make it form up.

    The new style Union connector that was bakelite a sort of porcelain/plastic type material was a bit more brittle but were more ridged enabling the casting to be less bulk and more room inside the connector for wiring even crimp terminals. Not a lot of more space since the plug was not made longer for more room between strain relief and terminal, it was kept to the same relative size as the original version, but at least the grip on the strain relief was slightly improved and there was room for crimp terminals making for a much safer connector. With some work you could also remove the pin to replace it or in making a grounded plug un-grounded without damaging the plug. Both grounded and ungrounded plugs were available with either age of plug in the end of the old style. The three hole individual conductor Union plug was also carried over into the more modern style and could be found up until asbestos wiring stopped being used and was replaced by cords inside fiberglass sleeves.
    To wire this plug, as with the above, you wanted to form it into a fork shape, but in this case because you were using crimp terminals, the terminal would do this and your wires were shorter. You would strip no more than 5/8" to ½" of wire, than cut 1/8" off the neutral and1/4" to 5/16" off the ground. You would than fold the neutral and hot over at 90° and strip 3/16" of insulation off the wires. Flag terminals which are ring terminals with the hole in them directly perpendicular to the axis of the wire so they make a sort of flag on the wire along with a stubby ring terminal for the ground were than crimped onto the conductors. You wanted to push the crimp into the insulation by about 1/16" so it bunched up around the crimp and provided some extra insulation for cable stretching/shrinking needs. This also meant that the ground in the center of the wire would about have the insulated terminal touching the outer jacket of the cable if done properly. If you made the wires too long, because the strain relief was so close to the terminals, the jacket would pull out of the strain relief and the conductors would rub up against the sharp edges of the strain relief hole. Unfortunately, the ground crimp might dig into and short out the other conductor’s insulation at this point since it about touched them, but that was a detail still less important than the extra safety improvement this type of plug had over the older style. Once well crimped, the wires would be electrically very safe because they were no longer what was under tension by a screw, nor was heat involved in making them, plus there was a little more room between the stripped portion of the wires. No more forming the stranded wire into circles than attempting to put a wire washer around it, or figuring out how to tin them without destroying the insulation etc. Just a question of getting a proper crimp onto the terminal - especially the flag terminal for finding a crimp tool to do it, or a proper crimp tool for the ground that often would carry all of the strain relief duties for the plug. Wires slipping out of the ground ring, improperly spliced - instead crushed crimps was a common problem. Don’t remember what my teachers used, but it took me years to find a crimp tool that would crimp the terminal properly and not crush or bend the flag part of it. Out of this reasoning, the screwing the crimped terminals to the wall technique and climbing it to test, even soldering the crimp might have sound reasoning behind it’s use in testing. Most people had hammers, and pliers, perhaps a wire stripper, but certainly no Klien #1005 crimp tool with the front cutting tip cut off so it would not damage the flag part of the crimp. Having found my Vatco #1900 tool, I quickly forgot how those that taught me to wire such plugs did it themselves be it proper Stakon tool or smashing it. I knew I needed a well defined tooth at the end of a crimp tool to crimp the terminal, but had no idea of what to use or where to find one. Smashing the crimp terminal while done is not the best option, it will not apply even pressure to all the strands of wire and will often open up the seam in allowing for individual strands to fall out of the crimp and cause a higher resistance. If some strands are not supported but other are, when the wire is pulled one of two things will happen. Either the conductors will resettle allowing more than all the conductors to fall out of the crimp, or those strands with too much pressure on them will break because there is too few of them under high crushing pressure to carry the weight applied in pulling them. Wires falling out of a crimp is nothing new flag terminal or not. I have some professionally built AC Distro racks that use flag terminals with wires falling out of the crimp even with the proper crimp tool used - just without sufficient pressure applied to the crimp. A few hundred such crimps per rack that have to have every wire tugged on now to verify they will not just fall out all by themselfs.

    While at least you could get the crimp terminals for this plug, they were not cheap or readily available thru a hardware store. Tech departments would perhaps buy a hundred at a time, but no more during the budget year. In other words, in spite of the better way, companies would naturally fall back to tinning the wire and or shoving the wire under the screw heads and hoping the wires did not arc too badly. Given the electrician put any forethought into what they were doing at all as I still constantly see these plugs in service with wires wrapped just around the terminal. When ever you inherit and become responsible for any slip plug, it should be opened up and inspected for proper strain relief and connection. The industry has far too widespread unsafe slip plugs in use in it - new or old of any style. New plugs designs were needed and well known to all as necessary or the industry might just switch to twist lock... as it did about this same time.

    My experience with the improved stage pin plug was in about the mid eighties though it might have been introduced later. Pinecrest given that’s the actual brand name, I believe was the brand I first saw, than Rosco amongst other companies developed a style of their own. While the plugs were longer, they were more shapely in design so the right angles that snagged on everything were removed from the plug. There was also all kinds of space for proper separation between conductors, conductors that would use the much easier to crimp ring terminal such as on the Union’s ground pin or even the more normal longer ring terminal, and still allow extra room for an improved strain relief. On later forms of this style it was one that could have a strain relief block inserted into it for smaller wires, or even use a Heyco fitting for other sorts of small cords including zip cord. The pins were stronger and much easier to take out of the plug for replacement. Screws were switched from flat head to the much easier to use Phillips screw with even a external lock washer added to prevent the screw from coming loose. Along with time, it also came further stronger and improved materials used for the body and screws in the area of the strain relief that were closer together for more strength and less bending. The front of the wiring cover was also inserted into a self holding recess so it would prevent bending and add strength, if not later a third screw was added to the extended length plug. Vastly improved plug that could even have clear plastic covers applied over the terminals so you could observe what condition they were in. Great improvement to the design, much more expensive unfortunately in the end, but good improved design if the strain relief were a bit less than ideal, and it still took a proper crimp tool to ensure wires would not come loose. Such plugs are still widely available and useful. Union further improved on their old style plug types to follow suite with the same extended length plugs with extra room for wiring and normal ring terminals, however the plug still has right angles to it’s design which snag on stuff when you pull on the cable.
    To install this cable onto a plug, you will want to strip 1" to 1.1/4" of jacket off the cord and cut 1/4" off the ground if not 1/8" off the neutral and 5/16" off the ground. This when the wire is folded into a fork shape to fit within the channels, will allow the wires to be the proper length without any extra slack in the wire which is hard to align. As with the above flag terminals, strip about 3/16" off the insulation on the conductors, and shove the ring terminals onto the wire so the insulation is pushed back and bunched up around the crimp terminal. This will allow for a little extra insulation to be available should the insulation on the conductor be pulled. Crimp the terminals with a Stakon tool sufficient to hold should it be tested in the above screwing to the wall test, than install it into the terminals. Normal tightness of screw terminals would be 1/4 turn past hand tight meaning 1/4 turn past what is tight without holding the screw driver with a huge amount of force - what is sufficient to hold the screw driver easily, than 1/4 turn more with some force.

    Advanced Devices/Bates further refined the design and became the industry standard for stage pin plugs. They designed a very good plug that was tapered in shape so it would not snag, had three screws for more support of the cover, and a set of double strain relief blocks that fit into a channel allowing it to fit and adjust to just about any type of wire as long as you were able to read the directions on the package and make some general choices of proper tension off that. It also featured ferrules - tinned copper tubes which did not necessitate a proper crimp tool to install, of which fit into a set screw opening instead of having to wrap around a screw. Much easier for installations in the field with no more than a wire stripper and Phillips screw driver. The plugs were initially cheap to buy and the ferrules for them were cheap enough by the hundred that anyone not lazy could keep them in stock. Ferrules are the imitating factor in this plug, easy to loose, and rarely in your pocket on a ladder, but in the end no different than not having any ring terminals in stock and clamping directly to the wire with it being bad practice. There was even a hole designed into the plug the Rosco type followed so you could insert a tie line thru the plug or bolt groups of plugs together. Much better design, one that a few other companies have copied the design to and “improved” in materials, than moved off shore to make their own very cost effective alternative sold a little more cheap in price yet. The bates plug given a larger size than the old Union with unsupported space in it’s body has been known to develop puncture holes in it, or crack under too much tension on the strain relief. It like all plugs breaks due to the higher hardness plastic necessary for thinner walled plugs, this is the primary thing improved upon in other companies designs for the plug. Often you do get what you pay for in the alternative Bates style plug however between strain reliefs which are not universal parts - thus if you mix brands though the strain relief insert looks the same, a Bates strain relief will not fit inside a Offshore brand plug, and the plastic screws holding it together are slightly smaller in shaft dia. This means the plastic screw holding it together breaks easier on installation and if you use a Bates plastic screw on it, you will not be able to re-install a offshore plastic screw into the plug - it will be stripped out.
    Overall, most parts such as the ferrule, black oxide plastic screws, and brass screws on the bates plug are readily available thru McMaster Carr or other sources. Should your plastic screw holes strip out, there are other plastic cover holding screws on the market as a direct replacement unlike with the old Union style that you could about get a replacement sheet metal screw for but would about as often crack the body of the plug once installed. There is also a version of the pin available using a 4-pin indent crimp tool to absolutely lock the wire into the terminal instead of having a screw that can come loose. Faster on the labor, cheaper and the assurance it will not come loose for factory install situations, you don’t need a ferrule or set screw anymore.

    Beyond the ferrule which is easy to install without special tools, the major advantage of this plug over all other stage pin plugs is the strain relief that at least adequately holds all forms of cable. 12/3 SO wire gets no strain relief. 14/3 SO wire gets a single rounded strain relief. 12/3 SJ gets a single flat one, 14/3 SJ and 16/3 SO gets two rounded. 16ga single conductor lamp cord in fiberglass sleeving gets a rounded and flat strain relief insert. And Zip cord or 18ga lamp cord in fiberglass gets two on the flat. People not following directions is the only major problem with this style of strain relief. Things like 12/3 SJ wire put between two rounded strain reliefs will cause the insulation between conductors to become displaced which with flexing can cause a short between conductors. In general the largest problems with the connector strain relief are that the edges are while slightly rounded still sharp enough to cut into rubber, the strain relief being installed either too tight or loose from not following directions, and the low coefficient of friction values on fiberglass sleeving when paired up with plastic allowing at times the fiberglass to slip out of the plug.
    Displacement and on smaller wires- the flattening out of the wire under the strain relief and the while improved grip of fiberglass sleeving still almost necessitates use of other materials to help it. Should you wish to put the plug on a thermoplastic wire that has less compressive qualities to it, you are better off installing some PVC or Nylon tubing over the cable so it will become a larger wire size and the tubing will compress but still grip the cable better. For say a 18/3 IEC cable such as might be off the back of your computer monitor, it uses a ±1/4" dia. cord. You would want to use a double rounded insert into it, but it still will flatten out the plastic cord more than it will want to be once it gets old or exposed to chemicals in the air such as fog that will break it down. Instead, if you insert a say 1/6" wall tubing matched to the size of the cable over the cord, the tubing will compress as per rubberized wire, yet like a ferrule retain the cord in applying equal pressure to it’s circumference. All thermoplastic wire can benefit by some softer material between it and the plug. That material will also prevent too much flex between the wire and the somewhat sharp edges of the strain relief that can cut into it.
    Going back to the friction tape, it’s also still of value in keeping that fiberglass sleeving from slipping some 100+ years after the friction tape was invented and scores of years since it was famous for use with Union plugs. Tech people always used to bitch and complain about it’s use, now they bitch about it’s reappearance and often would prefer just replacing the sleeving as it wears out or slips. It on at least the space between cord and fiberglass sleeving will provide when about a double layer of it, enough springiness to mold around the wires and grip the normally fiberglass wire to fiberglass sleeving to plastic junction that has been known to slide. 2" Of the friction tape with both ends under the strain relief will allow sufficient gripping power of the round and flat strain relief inserts to grip the wire without adverse damage to it, and prevent it from slipping out. This as opposed to a double wrapped cable tie inside the connector that could grip and prevent the fiberglass from slipping out but is more a question of getting the cable tie tight enough. If that fiberglass slips all the strain relief duties fall upon the set screw tension on the ferrule wrapped conductors - primarily the neutral. A 16 ga wire is not strong enough not to break under tension. You need an adequate strain relief. Friction tape above when followed thru with a double layer plus some of it above the fiberglass sleeving will allow for a very tight grip on the wires when used with a double rounded strain relief insert that will hold really well and also like the PVC tubing, prevent the wire from bending too close to the connector which is a common reason not only the fiberglass sleeving wears out and cuts, but the inner conductors also break and wear. Exposed friction tape however is a magnet for dirt and goeyness when fresh however. It will hold the cable well but has to be balanced with the above cleanness of the plug.
    To install the wires onto this plug, you don’t just strip the jacket and insert the wires with ferrules onto the set screws. There are issues such as that bolting thru hole between ground and hot that get in the way, plus the actual distance any one wire has to travel to get into position is different on a flat connector than it would be from a equally distant Edison plug. If you make the neutral and especially hot wires stretch to their terminals without adjusting for length, you are asking for something to come loose if not short out. Strip 1.1/4" of wire off the jacket. Cut the Neutral for 1/4" and the ground for ½" shorter. To strip the wire, use a quality pair of diagonal side cutting pliers in pinching the cable sufficient to grab it and pull or rock it back some off the conductors, than cut it. Grab another part of the insulation, pull it back and cut it. Continue on with that two more times, than bend the wire so the jacket breaks apart with stretching. Look at the wire you are bending to ensure you did not nick the insulation over conductors. If the jacket does not pull apart freely, while the jacket is bent, press down lightly with the dikes and it should cut without cutting into the insulation below. Pull the insulation free after most of it is cut.
    Next form the conductors into a fork with the hot being slightly wider apart from the ground than the neutral. This has the advantage of pre-forming the wires so they align with the holes they will go into and pre-arranging the wires conductors so the ones on the outside of the bend are shorter than those on the short side of the bend. Do this and no wires will be pulled out of the ferrule. Don’t pre-bend your wire and once it is bent, it will have conductors inside the ferrule of different lengths which will not be compressed upon evenly. Strip 1/4" off the insulation and insert a ferrule onto the wire. Grab the flair out of the ferrule with the pliers or wire gripping front of the stripper at the flair out, and push the ferrule down on the wire by 1/16" so conductors are pushed out the front of it and the insulation bunches up around the ferrule. On fixture cord, strip 5/16" and don’t bother pushing down on it. In either case, with the tip of the stripper at the flair, compress or sort of pre-crimp the ferrule to the wire. This will hold the wire to the ferrule but not obstruct it from fitting into the terminal. Wire will be sticking out the top of the ferrule, cut it off so there is no strands sticking out which will prevent the wire from sitting well inside the terminal hole. It is the extra wire after the bend to fork shape that if within the terminal will prevent sufficient contact. Once this is done it’s easy to insert wire with ferrule as one into all terminals of the plug and tighten them down with the 1/4 turn tension over hand tight.

    The ferrules provided with stage pin plugs are designed for 12 ga wire and this can become a problem. It’s as if you were sticking the 12ga wire into the opening of the pin without a ferrule. 16ga wire without the proper size of ferrule will not receive the same pressure on all conductors as above with cold solder and unsoldered wires into screw terminals on other types of plug. Only now the problem of doing so is worse than the head of a screw tightening onto a wire, we are talking about the tip of the screw cutting into conductors. At least only those conductors directly under the screw. Those without direct pressure of the screw get no tension and provide a high resistance connection. Inserting wire into a too large ferrule is not a cure to this either because the wire has nothing wrapping it’s circumference in applying equal pressure around all strands much less the 12ga ferrule is just going to flatten out and since it’s not full of wire, the screw will most likely just cut right thru it and any strands of wire under it. It’s possible to cut your wires instead of attaching them to the set screw.
    Any wire when doubled up will about equal a wire gauge three sizes larger in size or three sizes small in number than the original gauge. Take the above 16ga wire, when you strip double it’s length, than fold it up back upon itself, it now equals a 13ga wire which with the fold is plenty close to the 12ga of the wire ferrule. Tipple fold a 18ga wire into a 12ga ferrule and it’s the same principal. This works well for the above two sizes of wire in making them occupy the space of the Bates style ferrule. It does not work so well for 14ga wire unless you again double the length, but in the last 1/4" of stripped wire, re-strip the wire down to a 16 or 18 ga. than fold it back. Remember while current travels down the circumference of the wire not it’s inside higher resistance, it also flows down the path of least resistance. In other words, while broken or stripping the outer conductors off a wire might on other things cause extra resistance, in this case since its just used as filler for the ferrule, the current will not receive extra heat by doing this. Instead the current will flow into the properly stripped section of the wire first without worrying about the cut into conductors. Fold those remaining strands over and use them for filler on the ferrule. There is also a problem with tinned wire such as you will find on fixture wire. It’s the same relative size as cable if at times less strands for thicker more heat resistant sizes, but in general heat wire is tinned copper coated and it is not as flexible much less able to bend as easily. This wire will not bend back on itself without stripping it down to a smaller size sufficient to fit within the ferrule. Even than it’s difficult to fit within a ferrule.
    Fixture wire is very difficult to make work with a 12ga ferrule. Most just ignore there is a problem, yet every time they open up a plug used for a fixture and find a ferrule and strands of wire within it stuck within the stage pin plugs terminal, they must say to themselves there is something wrong here. Every time they see a melted down plug or one with loose terminals, they assume someone did not tighten down the screws enough. It’s possible, but given such tension is standard practice unless using power tools without verifying the proper tension, it is more likely the wire just settled or broke within the far tool large ferrule and the set screw was now not providing sufficient tension on the wire. That when coupled with cables that had badly applied strain reliefs allowed the wires to slip out of the terminal and arc at worst, or just create a high heat resistance condition. Happens all the time with 60amp stage pin plugs on 5Kw lighting equipment. Yes copper expands and contracts, but if there were sufficient retention around the strands of wire in the first place, they would not resettle and cause a loose connection for higher resistance. It’s bad to put too much tension on a terminal as it also causes resistance, but by far easier to end up with the wire once warm expanding and moving itself so as to accommodate for the larger size. Than next time the plug is used, with it’s wires no longer tight because they have contracted, they are a high resistance connection.

    There is two really good cures for the smaller wires in stage pin plug problem. First is to use crimp on plugs given you have a four pin indent tool and don’t mind throwing out the plug if the wire needs to be removed. Or you can use the proper size of ferrule in the terminal, than since it’s too small for the 10ga wire hole, on the bates plug, inserting the 16ga ferrule into the 12ga ferrule so both the wire is encased within the proper ferrule and the outer ferrule is sufficient in size to clamp down under the screw terminal - at this point even with a ferrule of double wall thickness so given the smaller size of the individual strands, the conductors are no longer cut by the twisting screw pressure on them. To that extent, insulated end ferrules with a PVC sleeve that fits over the insulation on the wire are cheap and have the benefit of allowing no exposure of bare wire outside of the plug should the insulation shrink back some. Simple process requiring an extra part kept in stock and an extra step in installation of the plug, but it’s benefits are simple should you wish a really good connection.
    By the way don’t be touching the ferrule more than necessary, much less especially the stripped wire much. The oils from your fingers like with the effects of them on halogen lamps will create resistance if not corrode the wire. Just a slight detail that will require deoxidant on connections to currents normally higher than 20 amps, but still important as a practice.
    Finally, a note on using plugs for twofers. Lots of companies just shove double the size of wire into a plug’s terminals and call it a twofer. Remember that this is theater and we are held to a higher sense of doing what is right than what is in your house. The NEC specifically bans the use of plugs/connectors as interconnection devices. This means a plug cannot nor will ever be made to make such a thing easier to do much less should ever be used. Think about this as the plug twofer is constructed. You certainly cannot fit two pieces of 12/3 even SJ cable into the strain releif without well overstressing it. You can about do so with two cords of MTW wire inside fiberglass, but even than it’s really clamping down unsafely onto the wires. The plug is rated for 20 amps. Any cables used under that 12/3 will not be sufficient for a perspective load given they don’t go to a fixture. The manufacturers could design a double wide strain relief, but than they would be responsible for doing something against the NEC that states something like any cord mounted splices need to be within vulcanized or other approved cord mounted cable mountings. Doubt the plug could than get a UL listing in not being code compliant. I have seen one bates plug with the strain relief ground out for a larger size, thought it was interesting and well done, but than realized that once you modify a connector it’s your complete liability over the plug. Should it cause a fire which is directly responsible from the plug, you not the manufacturer are now liable for it.
    Done all the time in the field. Someone will cut up one of my cables and shove both cords into a plug. Sometimes they will strip extra jacket away from the cable than tape up the exposed conductors so they can fit the cover on. Other times they will no doubt Vise grip the cover into place and absolutely smash the wires dangerously together. Some will even add a cable tie to the cords coming out of the strain relief so they when bent apart don’t at least instantly get cut jackets from the plug. Almost nobody but the most skilled of tech person is able to get the wires into the pin hole, even without crimped and folded individual ferrules used. After all, nobody has a handy ferrule crimp tool with them which being square once crimped would not work well, much less they don’t have access to double wire ferrules which are designed to house double wires within one insulated ferrule. This will fit within the opening and won’t have the problems of stray strands needing to be cut or falling outside the opening. In other words, it might seem simple to make a twofer out of a plug, but avoid doing so if at all possible, it’s going to be a high resistance connection and one the plug not only is not designed for but one that is against your local codes.

    No more real notes other than if assembling more than one plug at a time or working with a buddy, it’s by far faster and safer to do it in an assembly line. Cut all cords of insulation, arrange the wire next step, than strip and install the ferrules. While you do this, your buddy preps the plugs. When he or she is finished, he starts putting the wires into the terminals and screwing them down. You take the plugs than and install the covers after verifying each wire went to the proper terminal. Even than always test your work after assembled. But if you break your work up into simple one to three part steps, over a number of devices, it’s very easy to do the same thing every time without any mistakes you forgot to either do or look at.
     
  2. Reggie

    Reggie Member

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    Re: Installation of a stage pin plug on a cable, twofers?

    So how can a stagepin twofer ever be made correctly? I see in the Mole-Richarson catalog that I can purchase factory made 20A twofers and even a 100A stage pin to 60A twofer. Are they manufacturing special plugs for this? From what I can see in their catalog, it doesn't seem like they have manufactured a special 100A plug for this purpose.
     
  3. Nephilim

    Nephilim Active Member

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    Re: Installation of a stage pin plug on a cable, plus histor

    If they're anything like the twist-lok twofers I've seen, there's a moulded piece that's a way away from the plug where the split is encased.
     
  4. ship

    ship Senior Team Emeritus Premium Member

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    That would be about the proper way of making a twofer such molded or volconized covered inline splices. TMB sells the Woodham brand of SO grade twofer, it's about the best on the market and for me at least also no more expensive than some thermoplasitc type that never seems to get the bonding issue right.'


    I have seen many things over the years that are grey in compliance, even well done but still in the end, a plug is an absolute without plausable exception that I'm aware of for our purposes, not acceptable much less designed to be a twofer as it than becomes an interconnection device. Cords in general are not allowed such things unless very specifically done. However given this, is a store bought cube tap a interconnection device, much less a stage pin cube tap if they still make such things? Is a CamLoc Y or Cube tap a interconnection device given it's got a male on it? No such things are not, they are different than a plug designed for one purpose but used for another. Such cube taps are engineered for that purpose and a normal cord mount plug is not. Have no fear, the electrical industry breaks the interconnection device just as much if not more. Lots of wires with a looped section around it's screw terminal that is just a section of wire without insulation around a terminal before it goes onto another device. Against code, specifically yes, done, even done well, at times yes.

    The point is you do not do such things unless absolutely necessary, than you destroy the item, using a plug as a perminant twofer is against code for good reasons above and should not be part of your inventory. As said, if you can't afford the $15 to $50 dollars to do it properly you should not be doing it. Cutting corners in our industry is not the solution. I have made such interconnection devices. A bunch of whole 10 female outlet strings on one cable. Safe as I could yes, ordered to do so also yes. Still in inventory and used yes. Used for a specific application also yes. Looking for a code compliant way to do this also, yes.

    I even have a stage pin male to 6-outlet female tap in stock. Actually two of them. Such things have a purpose. They are locked up and only used for specific applications.

    There is something to be said about the spirit of the code and professional quality making a exception for specific applications. Any inspector will agree to an exception even if otherwise clearly against the code. There is a difference however between intent to not comply because of budget and intent because of necessity. That is something to consider in being compliant to and following the NEC. Built in a professional manor has a large role in the NEC.

    In my posting about ancient Union plugs with the three strain relief holes, I cited them being used for twofers some 10 to 30 years after constructed. Overall, I would use and do use such twofers. Do I accept a bunch of wires shoved into a Bates plug, especially if the person constructing them could not get a ferrule around the wires, nope. Large difference between what materials are used and the quality of the application.

    Hope that helps. Do you need to throw out all your twofers that are against code? Certainly not. Should you look at phasing them out with code compiant ones once told the old ones will not work? That's smart tech and reasonable even if more money to be compliant. Buy them without plugs, it's cheaper.
     
  5. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    Re: Installation of a stage pin plug on a cable, plus histor

    Very interesting. I think that there are some fundamental differences between the US and Australia (and probably elsewhere). From what I can understand, you have stricter guidelines than here. I have tried to access the NEC codes (for my own information and so I can try to understand your system) via the web but can only find places to buy a copy. However, having said that, things are starting to tighten up here, which can only be a good thing. The most current AEIA (Australian Entertainment Industry Association) and Media Entertainment and Arts Alliance’s Safety Guidelines for the Entertainment Industry that I could find is dated August 2001. http://www.alliance.org.au/hot/submissions/eisafety.pdf

    There is certainly a lot more of an awareness of safety issues now, and lets face the facts, safety should be the number one priority on your list.

    Something that I find interesting is the fact that we have to have our power cables tested and any equipment that we build, such as 3 phase disros, power adaptors, splitters etc should all be tested and certified by a qualified electrician. There is some irony in this however, as the tags are good for a 12 month period and some people honestly believe that the tag will protect them (a little like Volvo drivers) no matter what happens and that any problems will only become dangerous when the tag expires. What the tag really means is “at the time this was tested it was safe and in working order”. I have seen power leads in which the outer jacket has been pulled out of the plug exposing the individual sheaths, or torn and split, yet still in use. Whilst the lead will work, by definition, it is unsafe and should be taken out of use until repaired and re-tested.

    Twofers are an interesting issue here as well, as the old style will not easily get tagged by an electrician (if at all) as there is a junction placed within the male plug. In many instances, the body of the plug is filled with epoxy resin or hot glue. Other practices are also being phased out, such as the use of installation purpose 3 phase cable for extension leads.

    Just my perspective based on my own experience and I guess at the end of the day the take home message is the same.

    If anyone does have a link to the NEC codes I would be interested in having a look.

    Cheers,
     
  6. Reggie

    Reggie Member

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    Re: Making a splitter, not a twofer

    Ship,
    I hope this clarifies my question to you and everyone else on the board. First, I should have used the term "Splitter" not "Twofer" , second, here is a link to the Mole-Richarson page with the type of splitter I was inquiing about.

    http://extranet.mole.com/public/index.cgi?cmd=view_item&parent=-1899-1950-1953-1973&id=10473

    How can this be made safely? You would be trying to fit two #6 wires into a terminal designed to take a single #4.
     
  7. ship

    ship Senior Team Emeritus Premium Member

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    Having stuff certified by a electrical engineer or Master Electrician here would be the norm for the mass produced gear you buy here. For instance, what you buy from ETC would come from a electrical engineer, than even be tested by a private and recognized testing agency such as UL - Underwriters Laboratories. On the other hand, I would not expect a electrical engineer to certify every plug installed on one of their fixtures. They might set up the standards and practices but after that anyone can put a plug on a cable as long as there is adequate supervision. This is a factory. The people installing cords on your TV’s would not be expected to have a electrician or electrical engineer manually test your gear either. Standards and quality control would about cover the liability and that satisfies most local codes especially with the UL listing to the gear.

    For other less marketed things such as a AC Distro unit from a major distributer such as Motion Labs, in a unit that is built to the customer specifications, it would be expected to be designed and approved of by an electrical engineer. Since it is a one time design or less than a production run, it would not be cost effective to have UL test the unit but you would be assured an electrical engineer has certified it as safe and they can pull up the records both for it’s design and certification. The hoist/motor control cable they sell will while more mass marketed would also be approved of and done like the fixture plugs above, but not necessarily UL listed in testing. Smaller company and smaller volume because it’s for a specific task. Should there be a problem their insurance blanket policy and the electrical engineer that specified how it was to be done would be on record and sufficient should there be a problem.

    After that, dependant upon what percentage of your business is manufacturing electrical appliances for resale. There might be a staff Master Electrician such as Chicago Scenic has to do the install electrical work and take care of the shop’s equipment on anything from installing a new plug on a drill to making up a pneumatic lift controller console for resale or a show. This person is designated by the company and is specified on the insurance to be doing such work having also passed the Master Electrician’s test for the local authority as would be expected for any company that markets electrical appliances and installs them under building permit or installed theater show as something custom built for the application.

    After that, I perhaps build one major device per year for resale and am not licenced as a electrician but having proven skill and aptitude and having gone thru at least three years of what I do getting inspected by the shop’s old Master Electrician that also is not licenced, I am one of only two people designated to do this type of thing out of something like 100 employees. The old man and I constantly butt heads on style but always agree upon what is safe in the end. If he does not approve I would not do so after hours of debate. For our company, anyone can build an Edison cord, but one of us are required to supervise it’s construction in one of two ways. This takes any form from step by step standing over the person if they have not demonstrated the skill yet to stopping by and offering tips in general over a certain period of time. There is at very least also the department manager for that department watching what is done, than after that one of the two of the ME’s if not both that do their best to stick their nose into what is done. We are liable for both training and what is constructed and that satisfies liability. After that anything that’s complex such as wiring a 5,000 watt Fresnel or building a chain hoist controller comes to see one of us, usually me because I’m faster and the old man spends his days as the Master Rigger/Hoist service person now. Thus referring to him as the old Master Electrician in that he does not deal with the general electrics anymore, but still pokes his nose into anything I’m doing when around. He comes to see me about NEC issues since I have a better memory for them, I see him for other “can I do this” things that I don’t have experience with which is constantly becoming less and less. In another 20 years such as his experience with the company as it’s Master Electrician, I will perhaps be on his level for all he knows plus above that what I know he is not as good with. Given the two designated ME’s for it’s size the companies’s insurance blanket policy as already set up as a resale venture covers any work we do but does not necessarily make it approved without inspection and approval by the local electrical inspector that has jurisdiction over approving non-certified and listed gear. Most of what we build to sell will be installed by a licenced electrical contractor and they are expected to inspect and approve of the equipment thus that licence thing is done for permanent work. The electrician installing the equipment accepts partial liability since it is his choice to install or not install the gear. We do not nor cannot install permanent gear. At least until such a time as we hire someone with a licence to do the work or until I get my licence to do so. In other words, we can build the gear but cannot install it. What we build is also subject to the local inspector’s approval, but in general given specified people supervising or constructing the gear, it’s covered on the insurance and that about suffices for most inspectors given the size of the liability coverage - something like a million or five dollars.

    In all there are designated people for any company here responsible and liable for the work that is done. A Technical Director is responsible for everything that goes on the stage including all of it’s equipment. Under him or her is the Master Electrician. Technically for a theater the Technical Director is the only person able to do work on the building electrics by our code. Chicago Code at least, which is our major set of rules. The NEC is a general guideline that is overall accepted by the local jurisdictions, but by law it is not, your local city has the overall enforcing policy over what they accept or change according to the NEC or their own changes to it such as 4 conductors per conduit no matter the size as per Chicago Code. The TD is acceptable in leu of a licenced electrician to do work to that specific place he is responsible for, or to at least supervise those designated under him - their work becoming his as per approval record. This is both a insurance liability thing and a practical thing. The person at the theater designated to do such things is most likely by name insured to be doing so and they are covered on the liability for the policy, but dependant upon the local code also. A ME/TD might be able to re-wire a dressing room, or by code they might not be able to do physical wiring to the building same. Anyone else doing major work such as a student might not be covered for something major without direct supervision, and for minor stuff under inspection of what’s done supervision by the designated person. Thus my concerns when I hear about students wiring a control board or re-wiring things. I would doubt both the local electrical code would allow for the student without supervision to do any such thing, much less the school board that is on government or state property in having it’s own jurisdiction.

    Anyway, overt or not, my assistant for instance as would be the Assistant ME as it were or in most places the ME to the TD since it’s not a theater and we don’t have a TD, has to have constant supervision until such a time that my boss - the general manager and top boss, stops asking me if I’m watching what she is doing and she is specified as a ME for the equipment. No doubt at all the General Manager was asking the old ME to look in on what I’m doing over the years either. Even I have certain things I’m not allowed to touch. For instance, while I can wire the building and construct parts to the antiquated service equipment, any work to our transformers would have to be done by either the senior ME, the licenced electrical contractor the company uses or the licenced ME for a major electrical equipment company we deal with for such gear. He works on our transformers, I swap out the ballasts from 277V to 208V for his own fixtures. Different levels of experience and trust. It’s expected under our system that one of the two electricians will switch out an Edison receptacle in the wall without having to hire in the electrical contractor, but even for something as simple as that, there are only two approved people, an that not only allows our insurance company to be happy, but qualifies as approved by the local electrical inspectors.

    So for adaptors, it’s something that’s tested on specifying how it’s done, than supervised by one of two designated people that are certified by the company. Anything not up to spec gets destroyed immediately and the electrician told of policy and on notice. This makes it all sort of similar to what conditions you have. In fact your Aussie electrical code is probably based upon the general policies of our NEC. Differences would be the obvious things necessary for the difference in voltage and frequency, but other than that and it’s own major changes, someone will have read the NEC and in general adopted it’s changes to your own policies. You can do what ever you want, but to be on the up and up, there is similar levels of approval and testing/inspection. Just a question of what the code says is that qualified electrician. Given a really small theater where by default the director with actor training is also the TD, what complies with code for his approval might be in question because there are some guidelines for apprentiship and training required to qualify for ME or TD - supervisor status by code. A home owner can do what he or she will, but above that is theaters and places of assembly to which there is other rules. This would assume the goal of having qualified people doing the work instead of someone by default being that testing/approval person and it being unsafe to inhabit.

    We don’t require tags, but do require manufacturer stickers and records of who constructed what plus the design for it on file as being approved by the authority on it. It’s for instance against code to remove a wiring diagram from a main circuit breaker panel. Can’t drill thru it, but you can move it. If you attempt to move such a sticker but rip it by mistake, by NEC the equipment is delisted and subject to other forms of approval and liability or acceptance by the local inspector. Does not often happen that something professionally constructed will not pass inspection, just as it is not likely a inspector will open up a stage pin plug, but they have the option.

    By the way, I have seen filled normally silicone type plugs before. Usually currently against NEC open faced plugs where you shove the wiring thru the plug and it’s exposed to the front. Even tried it myself in a pinch. Such things however are frowned upon very much. Proper cooling and other reasons. Plus hot glue and epoxy are not specified to be electrically safe in general as an insulator.

    On the NEC, it’s all for sale, I don’t expect anything is free except a subscription to CEE/EC&M’s news letter which I get and has frequent code changes outlined and discussions about the code in it’s interpretation. mailto:[email protected] It’s free but very rare it directly relates to the theater business. You kind of have to know the NEC to understand how it relates to your application. Still if nothing else, there is the “What’s Wrong Here” section in which electricians take photos of the odd and unsafe things they find and such reasons they are not code safe are explained.

    Anyway I hope that answers how for the most part our NEC works.
     
  8. ship

    ship Senior Team Emeritus Premium Member

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    First, two 6AWG wires when doubled up equal 3AWG. This frequently will be close enough to fit within a terminal designed for 4AWG. That’s without ferrule, but if like on better Edison plugs there is a plate that compresses onto the wires instead of a single set screw compressing onto a small section of the wire, that’s about acceptable or the best you can do. After that, you need that ferrule to make it fit with the same tension on all wires. What to do when a ferrule won’t fit within a hole for a terminal hole such as the 12ga ferrule attempting to fit within a hole for a 2K Fresnel that is designed for 14ga wire..

    Usually I use my Klien #1005 Stakon type crimp tool to induce a fold into the ferrule. Once the fold is into the wire to a certain hand tension, the ferrule completely wraps the wire and there is little to no open space between conductors, but it is not round. Were the wire fitting between two plates such as on a barrier strip without setscrews - plates instead, I would than use my Klien Conduit pliers in the flat right next to the pivot in finishing the fold in the ferrule and making it tight to the wire. Otherwise if it needs to be round, I would use the oval/round hole next to the crimp tooth, to shape the now folded ferrule back to round. After inducing the fold into the ferrule, there is less space occupied by wire with ferrule added to it’s dia.

    Otherwise for the installation of two wires into one hole, it’s the same idea, two wires into one ferrule. McMaster for instance sells two wire ferrules which have a PVC insulator on them which will force both wires together by the time you are done shoving the strands both at once into it. It’s a funnel to make both wires compress into one. Otherwise if for instance both wires are 12ga, than they will just about fit within a 10ga ferrule due to the extra space to easily fit the wire. This would be about the same as the double wire ferrule, only without the insulation. Than induce a fold into the ferrule and you have something that’s about 11AWG.

    There area also ferrule crimp tools on the market that serve the same purpose in reducing the overall dia. Of the ferrule. Unfortunately they are rectangular in crimp not round, but I’m sure Mole if they needed to crimp a ferrule on two wires needed something, they would have a round die for making the wires together in making the ferrule tight.

    The 100 and 60 amp plugs they use are very similar to those fiber ones available from Union Connector in being fiber instead of the Bates thermoplastic. I prefer this style myself because it withstands more abuse. They do use ferrules within the plug.

    As for code compliance, good question. First, it’s using individual conductors for a single plug, that’s by my interpretation against code. Than from that they are using a plug as an interconnection device. Now I would assume that the wire between plugs is rated for use without a jacket over conductors as with the DesignLab twofers I mention, but as for all cords fitting into the strain relief effectively, it’s no doubt easier to fit a #4 wire into the strain relief than two 4/3 cords. Than it being NEC compliant... I would assume Mole has it’s own staff electrician that has verified it’s exception to general rules, or since they are engineering the product completely they can get it wavered. This would seem an exception to the rule, if not something designed before the current code such as the Design Lab twofers also using individual conductors. Grandfather clause, exception to the code, engineered product?

    In any case, you could assume a few things. A electrical engineer certifying the equipment they 100 percent construct that you don’t have on plug type twofers, the plug was no doubt given how ancient equipment Mole still sells, was designed before this detail was written into code thus it’s granfathered, and their insurance covers the liability of selling such a product after it’s manufacture.

    In the end, I did not mean to imply such twofers cold not be constructed safely. I admitted to having constructed some with double wire ferrules such as single conductor #12 MTW wire in fiberglass strain relief myself did I not? I also said that I would not just throw out such expected to be 20 amp twofers immediately, but I would buy molded and proper twofers for my permanent use over repairing or constructing such things. Instead, what my intent was to say that You and I should and cannot be building such things, to do it properly we need to be buying at least the Y or twofer, and this Mole cord would be a major exception and possibly one that would not be allowed other than on a movie set.

    Also look at how it’s designed. It is using a 100amp plug with two 60amp receptacles. That’s by far safer than a 20amp plug with two 20amp receptacles. 20amps overload on the Mole twofer, 20 amps overload on the stage pin twofer. Difference is that 20 amps on a 100amp plug is 1/5 and 20 amps on a 20 amp plug is 100% overload possible. Can logically the 20 amp plug handle 200% of it’s power load?

    Finally the #4 wire probably will fit very easily install on the 100 Amp plug.
     
  9. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    Re: Installation of a stage pin plug on a cable, plus histor

    Thanks for that. Probably didn't write my initial post clearly enough. The main point is that the safety aspect in this indusrty is really being clamped down upon. Especially in the last 5 years or so which is causing some problems with some operators. Mainly it is in relation to unsafe practices that were never regulated or picked up in the past. It is really only the power extension leads that we have to have tagged and custom built distos. Anyone can put a plug on a fixture etc, so this aspect probably is similar and of course, anything purchased that is mass-produced you would expect to have been properly tested.

    I do all the wiring from 3 phase distribution to fixtures to replacing/adding wall sockets in the factory. Some of the work I am required to get approved, the other I am not. If anyone else wires anything, I will check it, sometimes during and always on completion.

    I have one question that relates to the previous post by Reggie and the image contained in the link he provided. My understanding is that this is a stagepin splitter that allows 2x 20A feeds to be pulled from a 60A feed. Nice and simple stuff as 20 x 2 = 40 which is well below the total load for the 60A feed. My only question here is in regards to the protection of the 20A feeds.

    I was always taught that as you reduce the rating, you insert an appropriate protection device at that point. In theory, what is preventing a piece of equipment that is plugged into the 20A feed failing and trying to pull the full 60A down the cable?

    This is why the old 3 phase to tails splitters are no longer legal in Australia (although there are still many in circulation and use). This splitter is really a very basic distro in which 3 240V 15A tails are wired into a 415V 32A plug, with the active of each tail connected to a different phase. To do this safely, your 3 phases must be protected and most are now either 6 way or 9 way units with individual circuit breakers per output and RCD protection.

    Just curious and will be interested in your thoughts and comments. I apologise that this is a very brief post but I am really under the pump at the moment!
     
  10. ship

    ship Senior Team Emeritus Premium Member

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    Yep I would agree. For instance, you are not allowed to do a L6-15R splice off a L6-30P plug - at least officially by code without a current limitating/protection device between the 30amp feed and the 15 amp outlet to a certain extent. You are allowed to tap a next higher feed however such as a L6-15R again receptacle off a L6-20P plug.

    Again, officially you can't do such things, is it done, yep. Is a electrician on site going to look at what he or she is plugging in even if properly licenced? Probably not, nor would the inspector notice unless he than you are having a bad day.

    I was forced at one point to make a three phase Edison adaptor to L21-30 outlet dute to a special application and purpose. Normally three individual 15 amp 120v plugs feeding a 30amp 120/208v three phase outlet would be a real no. First a outlet box such as you might find inside a wall in your house is not allowed persay on a cord, and if than only with an indicator light saying it's live. All knockout holes which I atleast had, were in place. Nothing large enough for a finger is allowed. It might have been a little more safe and acceptable had I gone for a L21-20 outlet, but since we do not use that style of outlet, it was not possible. There was also no circuit protection. In other words in this case, hopefully the individual circuit breakers would protect against 30 amp loads as opposed to 15 amp loades in overload or short circuit having no protection. But in this case also since there was three neutrals, it could also be assumed that there was decent capacity for an unbalanced load. The application was for into one of our distro racks that did not have hoist power L21-30 coming out of it. True three phase power was thus available, also it was used on our not house gear. Also qualified personel would be using the equipment. Or at least sufficiently q ualified people.

    So in this case, a electrical inspector might have frounde on the outlet, but it will not have been much more serious than not allowing it's use.

    The origional design for it had 20 amp Edison plugs for the adaptor which would comply as a step down size at least just as the 60amp plugs featured in Mole are a step down from the 100 amp male. Unfortunately the dimmer person on site having been a stage hand for at least 30 years now had never seen a 20 amp Edison plug before and thus proceeded to re-wire the plugs for the more normal 15 amp Edison - never having noticed nor wondering what that T-shape to the 20 amp Edison outlet means. I have not switched the adaptors back because there is too much chance of future even qualified personnel having the need to use the plugs. Sometimes even to the extent you make things safe, they still are not fully understood by the locals. You do the best you can in at least providing a professionally constructed product and one that is as safe as you are specifically allowed to build. After that it's up in the air.

    When not absolutely necessary however, you do attempt and follow the guidelines and only use your descression for the unique instances.
     
  11. ship

    ship Senior Team Emeritus Premium Member

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    Yep I would agree. For instance, you are not allowed to do a L6-15R splice off a L6-30P plug - at least officially by code without a current limitating/protection device between the 30amp feed and the 15 amp outlet to a certain extent. You are allowed to tap a next higher feed however such as a L6-15R again receptacle off a L6-20P plug.

    Again, officially you can't do such things, is it done, yep. Is a electrician on site going to look at what he or she is plugging in even if properly licenced? Probably not, nor would the inspector notice unless he than you are having a bad day.

    I was forced at one point to make a three phase Edison adaptor to L21-30 outlet dute to a special application and purpose. Normally three individual 15 amp 120v plugs feeding a 30amp 120/208v three phase outlet would be a real no. First a outlet box such as you might find inside a wall in your house is not allowed persay on a cord, and if than only with an indicator light saying it's live. All knockout holes which I atleast had, were in place. Nothing large enough for a finger is allowed. It might have been a little more safe and acceptable had I gone for a L21-20 outlet, but since we do not use that style of outlet, it was not possible. There was also no circuit protection. In other words in this case, hopefully the individual circuit breakers would protect against 30 amp loads as opposed to 15 amp loades in overload or short circuit having no protection. But in this case also since there was three neutrals, it could also be assumed that there was decent capacity for an unbalanced load. The application was for into one of our distro racks that did not have hoist power L21-30 coming out of it. True three phase power was thus available, also it was used on our not house gear. Also qualified personel would be using the equipment. Or at least sufficiently q ualified people.

    So in this case, a electrical inspector might have frounde on the outlet, but it will not have been much more serious than not allowing it's use.

    The origional design for it had 20 amp Edison plugs for the adaptor which would comply as a step down size at least just as the 60amp plugs featured in Mole are a step down from the 100 amp male. Unfortunately the dimmer person on site having been a stage hand for at least 30 years now had never seen a 20 amp Edison plug before and thus proceeded to re-wire the plugs for the more normal 15 amp Edison - never having noticed nor wondering what that T-shape to the 20 amp Edison outlet means. I have not switched the adaptors back because there is too much chance of future even qualified personnel having the need to use the plugs. Sometimes even to the extent you make things safe, they still are not fully understood by the locals. You do the best you can in at least providing a professionally constructed product and one that is as safe as you are specifically allowed to build. After that it's up in the air.

    When not absolutely necessary however, you do attempt and follow the guidelines and only use your descression for the unique instances. I will not for instance allow any adaptors that are 208v adapting to 120v Edison or that in reverse. If they want any such adaptor, they will use a 208v to stage pin and a stage pin to Edison and tape them together. Doing away with the stage pin common ground link between makes me responsible for having made such a plug as opposed to the person that installed two non-similar plugs together. When used as intended both adaptors are safe. If used in the wrong way by those qualified persons, they are at their own risk for not knowing better.
     
  12. Reggie

    Reggie Member

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    Re: Stagepin splitters

    Mayhem, you are right about the 100a to 60a splitter not having any protection and being a danger. Mole Richardson sells them both ways, fused and un-fused 60a bates. The wire used in the splitter is type SC.

    Ship, thanks for all the information regarding legalities and safe practices for building and repairing cables and properly installing plugs. I must admit that despite your cautions I will be making (for my own use, film work, not theater) two 100a splitters to use with my distribution equipment. Both my 60a and my 100a bates are both marked to accept SC wire only, my concern is if there is enough room in the strain relief of the 100a bates to accept six, #6 conductors. Would you downsize the ground wire to #8, as the NEC code suggests that you may?
     
  13. ship

    ship Senior Team Emeritus Premium Member

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    We all have to do at times what we don’t consider safe or what we would prefer not to be doing. The difference is we when we have to know better and will make it within the spirit of the code - or at least as compliant as possible, and as safe as possible given the necessity, limited specific use and use by qualified people at using it. In other words, if we don’t feel it safe, I would trust that you just as I would have a few words with the crew chief about it’s proper use, if not go to bat about doing any such thing.

    What size of feeder are you using and what size feeder holes are the 100amp plugs. Must admit that the largest I use are the 60Amp for my 5Kw Fresnels and feeder cable for them. I’m guessing you are trying to splice #6 SC for the adaptors given a 60 amp load? Given the 100amp plug is sized for somewhere between #4 and #2, than it might fit two conductors if you fold and size the ferrule. Good luck. It would be a challenge even to fit that many wires into a strain relief given SC.

    After that, a 100amp sixfer? Into one plug? I would mount a breakered sub panel on a painted plywood panel to do any such thing, (normal usage) but given this is not a possibility and it’s not full load, than I would daisy chain them as I did for my 20 amp sixfers. Given one plug is able to take two sets of wire, the female for it will be able to take that same amount of wire. This however necessitates a very small load of no more amperage than the max load of the conductor say ?54 amp max for #6 wire of SC. Otherwise, I would feed the #4 or #2/3 conductor off the plug, than go to a breakout box say no smaller than 4"x16"x16" given it’s an assumption on CU capacity, and Burndie the load given I could not breaker it which would be better. It’s physically not possible to even line splice safely otherwise inside a plug.

    As for the grounds, the NEC approves of it but I always like to see a full load capacity ground. In other words same gauge. This might be a short run and thus able to carry a longer load than a 100' cable of it in substandard ground, but I’m always hesitant to do so. Heck, I’m working on converting us from 5-wire 4/0 to six wire with tact and long term introduction. At least lowering the gauge of ground is not an issue for me. I would make the ground at least rated for the single output full load between the patch box and the plug. Than with doing the patch box, I would go for the #2 if it’s able to fit within the pins. #2 SC feeder is what rated for 180 Amps... Might be designed for the pin though it probably is not. A five wire if not 2/3 SC would be what I would attempt to run out of the 100amp plug to a patch/spider box. And that’s given I could not breaker the individual loads. Given suppliers, you might be able to find a #3/3 SC which would no doubt fit within the 100 amp plug. This would be optimum I think given the ferrules would not be sized properly. With a #2 ferrule, I would use the fold than reshape technique.


    The other option that is probably not yours would be to use grade MTW wire coming out of the 100amp plug given six conductors can fit within it (which I doubt) and fit out the strain relief. It’s going to be about ½ the size of SC. As long as you are using say a 5/8" fiberglass sleeving it’s protected by any normalness I’m used to in the conductor insulation being thick enough and protected by the sleeving. Than of course this is 20 amp not 60 amp usage I base this off of, and given I could not do a breaker panel or more simple a spider box. Also, since #6 MTW I believe is rated for 100 amp, you might be all set in that area. Unfortunately I believe #8 MTW is only rated for 45 Amps so you can’t use it for the feeder.

    NEC also allows for the sharing and downrating of the neutral, but especially now I would not attempt for that.

    Hope it helps. Go for the distro panel if not at least the spider box. I was just re-wiring a 5Kw Altman 5000L Fresnel today, (Yes by chance I really was rewiring such a thing,) but in my case I don’t have to deal with either high wattage spider boxes or much for the distro. They have the 6K dimmer packs they plug into and movie lights are not what we do a huge amount of. Spuds in themselfs are a major hassle for me in getting stuff to rig properly. Z clips are your friend in making something reverse sex of normal into normal at least stage lighting stand mount.We all have to do at times what we don’t consider safe or what we would prefer not to be doing. The difference is we when we have to know better and will make it within the spirit of the code - or at least as compliant as possible, and as safe as possible given the necessity, limited specific use and use by qualified people at using it. In other words, if we don’t feel it safe, I would trust that you just as I would have a few words with the crew chief about it’s proper use, if not go to bat about doing any such thing.

    What size of feeder are you using and what size feeder holes are the 100amp plugs. Must admit that the largest I use are the 60Amp for my 5Kw Fresnels and feeder cable for them. I’m guessing you are trying to splice #6 SC for the adaptors given a 60 amp load? Given the 100amp plug is sized for somewhere between #4 and #2, than it might fit two conductors if you fold and size the ferrule. Good luck. It would be a challenge even to fit that many wires into a strain relief given SC.

    After that, a 100amp sixfer? Into one plug? I would mount a breakered sub panel on a painted plywood panel to do any such thing, (normal usage) but given this is not a possibility and it’s not full load, than I would daisy chain them as I did for my 20 amp sixfers. Given one plug is able to take two sets of wire, the female for it will be able to take that same amount of wire. This however necessitates a very small load of no more amperage than the max load of the conductor say ?54 amp max for #6 wire of SC. Otherwise, I would feed the #4 or #2/3 conductor off the plug, than go to a breakout box say no smaller than 4"x16"x16" given it’s an assumption on CU capacity, and Burndie the load given I could not breaker it which would be better. It’s physically not possible to even line splice safely otherwise inside a plug.

    As for the grounds, the NEC approves of it but I always like to see a full load capacity ground. In other words same gauge. This might be a short run and thus able to carry a longer load than a 100' cable of it in substandard ground, but I’m always hesitant to do so. Heck, I’m working on converting us from 5-wire 4/0 to six wire with tact and long term introduction. At least lowering the gauge of ground is not an issue for me. I would make the ground at least rated for the single output full load between the patch box and the plug. Than with doing the patch box, I would go for the #2 if it’s able to fit within the pins. #2 SC feeder is what rated for 180 Amps... Might be designed for the pin though it probably is not. A five wire if not 2/3 SC would be what I would attempt to run out of the 100amp plug to a patch/spider box. And that’s given I could not breaker the individual loads. Given suppliers, you might be able to find a #3/3 SC which would no doubt fit within the 100 amp plug. This would be optimum I think given the ferrules would not be sized properly. With a #2 ferrule, I would use the fold than reshape technique.


    The other option that is probably not yours would be to use grade MTW wire coming out of the 100amp plug given six conductors can fit within it (which I doubt) and fit out the strain relief. It’s going to be about ½ the size of SC. As long as you are using say a 5/8" fiberglass sleeving it’s protected by any normalness I’m used to in the conductor insulation being thick enough and protected by the sleeving. Than of course this is 20 amp not 60 amp usage I base this off of, and given I could not do a breaker panel or more simple a spider box. Also, since #6 MTW I believe is rated for 100 amp, you might be all set in that area. Unfortunately I believe #8 MTW is only rated for 45 Amps so you can’t use it for the feeder.

    NEC also allows for the sharing and downrating of the neutral, but especially now I would not attempt for that.

    Hope it helps. Go for the distro panel if not at least the spider box. I was just re-wiring a 5Kw Altman 5000L Fresnel today, (Yes by chance I really was rewiring such a thing,) but in my case I don’t have to deal with either high wattage spider boxes or much for the distro. They have the 6K dimmer packs they plug into and movie lights are not what we do a huge amount of. Spuds in themselfs are a major hassle for me in getting stuff to rig properly. Z clips are your friend in making something reverse sex of normal into normal at least stage lighting stand mount.
     
  14. Mayhem

    Mayhem Senior Team Emeritus Premium Member

    Messages:
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    Location:
    Australia
    Ok – cut and paste and print this out and keep it very handy. Whist several of us have alluded to this, I think Ship has summed it up perfectly.

    The only other point I will make is that a show in NEVER worth risking a life over, so if you are concerned about a safety issue error on the side of caution.

    This is a problem that I have seen on several occasions with people not understanding that you can only pull as much juice as the total load will allow. I have personally seen people who think that a 32A 3 phase splitter will allow them to pull 32A off of each feed, therefore trying to suck over 60A from a single 32A outlet, albeit for a very short time.
     
  15. Reggie

    Reggie Member

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    Location:
    New Jersey
    Re: 100A to 60A spliiter

    Ship,
    The intended use of my splitters are to be able to feed a couple of 60A gang boxes or "spider boxes" from the 100A bates on my distribution box. Yes I realize I can not magically make 120A of power appear. So the two gang boxes will be sharing the available current, but each 20A edison (3) in the gang box is individually protected as well as the 100A bates in the distro. I'll have to measure the opening in the 100A bates plug to see if I can fit six #6, type SC wires. I was consideing downsizing the ground to save space in that area. Worse case scenario is that I order them from Mole-Richarson or some other manufacturer, but I was hoping to avoid the price which exceeds $200 per spliiter.
     
  16. ship

    ship Senior Team Emeritus Premium Member

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    371
    Location:
    Illinois
    Let me know how it works out. I don't think I have ever seen a 100amp stage plug much less have attempted what you are doing. Should be interesting and it would seem you know your task and necessary safety. $200.00 does not seem a bad price once you consider parts and more importantly labor and liability. You have to be already in the $100.00 range for parts, than what if it takes more than 4 hours in labor you just lost money, or what else could you be working on? I still would try not to downrate the ground if at all possible but realize it's probably going to be necessary to down rate it just to at best fit into the strain relief. Good luck.
     

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