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SO or SJO & what gauge: replacing asbestos

Discussion in 'Lighting and Electrics' started by soundlight, Dec 1, 2005.

  1. soundlight

    soundlight Well-Known Member

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    I'm going to be rewiring all of our lights (old century strand fresnels and 2331 ellipsoidals) that have asbestos wiring. What gauge cable can I get away with? Do I have to go with 12/3 SO? Or can I get 14/3 SO and 16/3 SO cable? Can I use SJO Cable? If so, what gauge? Also, where is the cheapest place to get the cable?

    Other question: what kind of protectective gear do I need when taking off the asbestos cords? Just a respirator and gloves? Should I wear clothes that I can throw away after doing the job?

    Other other question: where's the cheapest place to get male & female twistlocks?

    Thanks!!
     
  2. soundlight

    soundlight Well-Known Member

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    More info to help you advise me: fixtures are all lamped at 500 watts, and not rated for more, so they will not get bigger bulbs. So, 500 watts per fixture for the cable ratings.
     
  3. AVGuyAndy

    AVGuyAndy Active Member

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    I would go for 14/3 SO, black.
     
  4. Radman

    Radman Well-Known Member

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    Usually lights have individual insulated conductors (for ellipsoidals the leads usually come attached permanently to the lamp base) encased in a fiberglass sleeve. The leads are high temp rated (usually teflon or fiberglass insulated) and generally I see them as 14 awg. You should not use SO cable, as it is not rated for the high temp required for fixtures. Most theatrical suppliers should have these things.

    A couple of suppliers off the top of my head are BMI Supply, Stage Technology, and Mainstage Theatrical Supply. I don't know their current prices, they are just the first three I remember.
     
  5. BillESC

    BillESC Well-Known Member Premium Member

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    Ryan is correct... DO NOT USE S, SO or SJ cable as it will eventually degrade and short due to the heat.

    You can buy teflon leads specifically made for fixture rewires in sets along with woven fiberglass sleeving for covering the conductors.

    It is the correct way of doing it.

    Wear a mask when removing the old leads, when done immediately shower and have your cloths washed. You'll be fine.
     
  6. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    Lots of past discussions on this topic and whilst much of it relates to PAR can wiring, the principles are the same. As previously discussed, the cable needs to be of a sufficient temperature rating otherwise the insulation will simply perish, crack and fall off.

    A couple of past posts that I would suggest looking at include:

    http://www.controlbooth.com/ftopict-621.html

    http://www.controlbooth.com/ftopict-674.html

    I am sure there are others if you care to search for them. Whilst you are at it, also search for asbestos and the safety implications of doing what you plan to do. I would check with your local council/health department about safe disposal of asbestos. I would strongly urge that you get them removed and disposed of by professionals.
     
  7. AVGuyAndy

    AVGuyAndy Active Member

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    Bah, totally forgot about the sleeving. Yes, sleeving is the right way. 14g is still the way to go.
     
  8. ship

    ship Senior Team Emeritus Premium Member

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    I have to caution you against doing this project. I will attempt to provide a lot of information on how to do it, what’s possible in technique and what to watch for in general by memory, but also caution that you need supervision in doing so and should not mess with the fixtures as planned.

    In the question of SO verses SJ wire, which would be better as a fixture whip, it shows a lack of understanding of wire types used in electrical practice which also provides red flags to me in the wish to re-wire fixtures or remove the asbestos from them. Your intent is good but needs training and supervision in the practice of it. SO or SJ - both rubberized 90c wire are better than a thermoplastic SJT wire in some ways. As opposed to thermoplastic wire, grade S cable will not melt down, instead it will become brittle and flake off in entire sections. Dielectrically there is not much insulating qualities to it once overheated, but at least as opposed to a melted insulator, it will not be quite as dangerous. It however like SJT or SJE however could still start a fire when it gets hot enough. Such types of wire above are specifically not recommended for use within a stage lighting fixture unless part of a PAR can or similar fixture which has a lot more cooling and open area within it. Even than, such wire is not the best solution. Do not use extension cord no matter the type SO, SJ, SJE, SJT, SPT - any multi-conductor cords starting with a “S” wire as stage lighting fixture cord should not be used.

    Beyond this, follow very closely any mention of asbestos here, on stagecraft and other places, it is not something to be just removing by way of a few precautions taken. This removal project is potentially very dangerous to you and many others in the future that visit your work area. Such problems won't be seen immediately, instead they would show up 10 or 20 years from now. This is not a recommended project to be doing as a student. Have someone or a disposal company instead remove it and clean the fixture for you, than seek qualified supervision in attempting to re-wire the fixtures. Rewiring stuff without supervision is all a question of some potentially dangerous thing you forgot or did not know better than to watch out for. A second pair of eyes on what you do is always good even at least if only trained in general and not specifically for doing this.

    Another option:
    Otherwise, should it be determined that the fixtures are unsafe to be working on due to the asbestos, an option in not fighting the authority and sense of not risking your health for a hundred dollars worth of antiquated inefficient lighting fixture, would be to instead go with the flow of not service the equipment in question. Instead remove the lamp cap from the fixture and have it properly disposed of without attempting to remove it’s wiring. Save the rest of the fixture perhaps in all but the lamp cap, it’s wiring and plug. If the fixture is an antique, it should not be used and not require wiring within it. An antique fixture requires removal at least of the whip, and possibly qualified removal of the rest of the asbestos, but otherwise if it’s old but intended to be used, having all it’s original parts should not matter in functioning thus getting rid of the lamp cap and other components that require exposure will not be a problem.

    Such parts you get rid of can possibly be replaced thru the company that made the fixture if still in business, other companies making often extremely similar equipment or old fixture parts dealers that might stock old parts such as Hub Electric. Often if not the same some slight modification will be necessary to retrofit a lamp cap to your style. This can get complex but once the first one is figured out, subsequent ones are much easier. Study and take photos of the old lamp caps before thrown out. Slight modifications to it’s fit or how the base mounts to it’s plate sould be fairly easy to tinker with making work properly. Where possible buy the proper replacement parts or where other parts cannot be made to fit, your fixtures might not be worth the effort. This allowing the lamp cap assembly to be disposed of, while a pain in the rear in re-fitting the lamp base to a new cap would allow you potentially to less fight the problems of removing the asbestos and still keep the fixture. In retrofitting another type of old cap to a fixture, much modification to the lamp cap will be necessary anyway to modernize it, starting with a new lamp cap assembly or using an old one in the end will be almost the same effort needed. This could be a good option for replacement as opposed to needing to work with the asbestos. Even I would think twice about exposure to asbestos in ways I allowed myself to in the past.


    Below Are Some Notes On Old Radial Style Leko Rewiring. (This is for discussion in technique, parts and things to watch and not a step by step guide for those without training and supervision in doing so. There is many steps and techniques that will without a doubt not be mentioned or noted dependant upon the individual fixture. Trained eyes in helping with and supervising the project is necessary to wire a fixture safely.)

    Wire to be used or avoided:
    14ga wire on grade S cable is rated for 15 amps = 1,800w. On 200°c heat wire, it's commonly used for 2,000w loads. Are we sure this is the necessary gauge of wire to be using as recommended above???

    If the fixture is only rated for 500w, 18ga SF-2 silicone coated (sometimes Teflon) heat wire (200°c rated) would be sufficient. It comes either as a silicone wire or a silicone wire with fiberglass braided sleeve over it. If given the option, go with the fiberglass sleeve over individual silicone coated conductors as it adds an extra layer of protection over the silicone insulation.

    Given your fixture can probably also take a 750w lamp, it might be more safe to wire it with the more commonly used SF-2, 16ga wire. This is what gauge most Lekos are wired with. This would be a 19 strand wire which is more flexible in a cord whip than the otherwise higher temperature rated TGGT (250°c) wire that is less flexible and not recommended for a cord whip. Good wire the TGGT, but not needed for this purpose. This might be the type and temperature rating on some newer fixtures, but as opposed to commercially available TGGT, it would have smaller strands and more flexibility to it. In 14ga heat wire while it will certainly carry the load would also be less flexible in a fixture whip which is why it would not be best to be using due to wear and tear. Same reason one could wire a fixture with 12ga even 6ga heat wire but would not wish to beyond cost of the wire. There is no benefits to using a 14ga heat wire on a Leko unless rated for over 1,000 watts.

    Conductors Colorings:
    Given your fixtures will probably have a medium pre-focus type of polarized lamp base, (P-28s) you will need a white, black and green conductor. That hot (black) wire must be wired to the hot terminal of the plug which is the center contact of the lamp base. Otherwise should someone attempt to remove a lamp while the fixture is live, they will get a shock. This is common to all but double ended RSC type (R-7s) lamp bases and bi-pin or dual contact lamps in general. The reason for not needing color coding hot/neutral on such lamp bases like a par can, or modern Leko is they don’t have one of it’s conductors going to the outer shell of the lamp base, hot verses neutral does not matter on them unless of a special type required by the lamp itself. Anything using a screw base, pre-focus base or single contact bayonet base amongst others is dependant upon the neutral going to the outer shell of the lamp base and hot going to it’s center contact. Ignoring this is dangerous.
    If a black heat wire is not available, you can permanently otherwise color one of two white wires by way of paint marker or Sharpee as long as such coloring runs the length of the wire and is clearly different from the other conductor. A single or double stripe is sufficient as long as it runs the length of the conductor. While no longer necessary by code to run the length of the conductor, in a fixture whip as opposed to it’s terminating ends, such a marking would be a good idea and within the spirit of the code. It is not worth attempting to color the entire conductor. Part of the NEC stipulates professional quality of work and you won't be able to get a wire evenly black with just a marker. Cable companies dye the wire but this is not something easy for the end user to do to silicone or fiberglass.

    Your ground wire does not have to be rated for the full 200c, but should be the same wire gauge. It should be green and using a stripe of color is not within code for doing so. Either yellow/green (Euro) or entirely green is the only option for a fixture whip. Buy a pre-dyed ground wire. It is not required to be the same wire gauge - you can step it down one in size, but in general it is a good idea to make it rated at capacity. The concept of stepping down the temperature rating of the ground wire would be something visible about the conductors that would show if they are getting overly hot. One would much rather note your ground wire in melting down than the hot wires doing so after the fact. It also won't be as near the heat source. Type K Teflon Green 150c FEP wire would be sufficient for a ground. Having such lesser rated ground wire within the fixture will help in the fixture’s at least yearly inspection to note other problems where over heating needs to be found the cause of.

    Outer Sleeving Types:
    On the outer covering of the whip, normally type "0" fiberglass sleeving - 5/16" is the cable whip outer covering is used on lighting fixtures to cover the heat wire conductors. I like a 1/4" sleeve better - less chance of snagging. Normally all fiberglass sleeving will have a internal foil to it which helps reflect heat and could offer electrically a further layer of protection in carrying a short to ground instead of by way of your hand. While not really designated for this purpose that I’m aware of, I have seen this to be the case at times that a short will conduct thru the metallic liner of fiberglass sleeving for good or bad.

    There is other types of sleeving that can be used on the fixture to protect it’s conductors. Braided Polyester Mesh Sleeving is commonly available and used for a low cost retrofit. It is rated for only up to 257°F as opposed to High Temperature Woven Fiberglass Sleeving which is rated for 1,202°F. In such Poly sleeving and while both types snag, it has a more open weave to it that tends to snag easier. I’m not a great fan of this type of sleeving but many do use it effectively.

    A third type of sleeving available is not cheap but which solves the problems of wear and snagging is vinyl or silicone coated fiberglass sleeving. Vinyl coated fiberglass sleeving while not rated for as much in temperature and less flexible is a good somewhat economical fixture whip sleeving product where otherwise replacing fiberglass sleeving frequently. Silicone coated fiberglass sleeving on the other hand is really useful in both temperature and abrasion resistance. Were it not very expensive, it would be a really good other than limited application alternative to normal fiberglass sleeving.

    High Temperature Multi-Conductor Cable Whips:
    Another less used option would be to go with a "Rockbestos" type of multi-conductor cable. A few companies sell various versions of it and I believe actual Rockbestos brand is off the market though might still be available thru Altman or perhaps Mole Richardson. Basically given a wire gauge, it is like a SJ cable, only high temperature based in having a ground, neutral and hot within a outer jacket, all of which that is rated for 200c. Rockbestos is really good stuff. Some of the fixture whip multi conductor cable most other especially theater supply companies sell that is Euro based, it will work but is not as good. (My opinion.) It tends to have problems with oil from fog fluid and at times heat in cracking all the way down to the copper. It just does not react well to compression, abrasion and other things a more natural outer jacket/inner jacket with fillers type of cable will better deal with over that molded around the conductors. This especially will be the case should you nick in slightly cutting the jacket of the heat cable than pull on it. Such Euro heat cable/fixture wire will often be found on PAR can whips of a higher quality than SJT (75c) also used on them otherwise normally, or on other than domestic movie/location lights. The heat wire used on Kupo fixtures or available thru them might be a better alternative in being both thicker and different in style. Such heat wire is under study. Domestic movie/location lighting will either use Rockbestos or at times SO cable where it is not directly exposed to heat. Normally on the Euro type heat wire/fixture wire, the silicone will be molded around a set of frequently brown/blue/green-yellow conductors. Such cable will be rated for anything from 105°c, 150°c and 200°c, when buying it verify what the temperature rating it is. Rockbestos where still available has a outer sleeve that is not molded around conductors and is rated for 200c. Such a 200°c temperature on your conductors would be a good temperature rating to use on a Leko and every bit as similar to SF-2 in heat rating - only with a outer jacket more resistant to abrasion or snags. Anything in temperature rating less could melt down and cause problems.

    Heat wire or cable in general is available thru most theater suppliers, cable suppliers and of course McMaster Carr. A cable is an assembly of multiple - including three conductors within an outer jacket as opposed to a wire with only one conductor. A fixture whip within a fiberglass or other type of sleeving as an assembly of conductors than would also be a cable to some extent in having a protective sleeving over individual conductors. While done at times individual conductors should not be used without a protective jacket or sleeving over them, nor should a fixture be used with such jacket or sleeving having serious holes or cuts in it. Various glues such as Plyobond can glue together in preventing fraying a small cut or hole, but use of a fiberglass sleeve that is overly damaged defeats the purpose of a protection of the conductors and must be replaced.


    Things to check on the lamp base:
    Your lamp base if Medium Pre-focus (P-28s) will normally have screw terminals on it. This will allow direct termination of the replacement whip conductors to the lamp base without replacement of the lamp base. Before you attempt this, determine if the lamp base is worth saving. Does it have arcing and other damage to it's center contact? Is the pre-focus locking ring working properly, is the center spring providing enough tension and in general is it in good shape? While you can re-surface such a thing as a center contact, that's another project than rewiring and often might be more cost effective to just replace it. Other things to watch for would be rivets tight and not allowing the sell to be loose, porcelain not over heated or breaking and terminals the screws thread into not loose.

    Resurfacing of things like shutters and types of spray on graphite etc. or various paints would also be another topic of inspection or work, along with cleaning the lenses or inspecting the grade of them to be done while working on the fixture as a project.

    In this same concept, before you attempt to re-install an old lamp, have a look at it's center contact. This especially if you do replace a lamp base. Put a bad lamp into a good base and you just destroyed the new lamp base. Put a good lamp into a bad lamp base and it won’t have much better results. Start swapping out semi-used lamps between semi-used bases if not all around in good condition and you gain a lot of stuff with new problems added to them. The lamp should not show blackening or any arc welding on it’s contacts, the brass coloring should not be blue or white, or otherwise discolored much more than normal for brass, the cement should not be cracking in having large gaps or missing parts of it, the filament should not be sagging or coming loose from it’s support structure and the globe should not be blackening or otherwise misshapen.. The base contact points should be a smooth or semi-smooth surface and one without pits, discoloring or melted areas.

    New lamp bases are standardized parts in design so it won’t matter if really old or new or what brand it is, they will all fit. Replacing the lamp base when in doubt given they are not expensive is a very good solution.

    Check also the fiber insulator pad under the lamp base - washer like part between the lamp base and the mounting bracket for it. Hopefully it's a fiber one and not an asbestos one. Should it be blackened and crack rather than flex - replace it. Such things might be sold separately or come with new lamp bases. A good insulator here is very necessary. One that is damaged also does not dielectrically protect well. Fiber of a proper high temperature and dielectric resistance can be bought and cut to fit separately in sheet form if not otherwise available. Dielectric resistance meaning the amount of resistance to short a material has.


    Terminating the wires:
    On terminating the hot and neutral to the lamp base, do not attempt to just mount the wires directly under the screw terminal. As such wire heats up, it expands and contracts causing what was once a tight connection to loosen. You will almost never find an instance of purpose to have a stranded wire directly under a screw terminal without a plate, ferrule or terminal between it and the turning head of a screw. Don't over-tighten your screws either, this causes resistance due to the pressure and can strip the screw. 1/4 turn past finger tight is the normal rule.

    Tinning your wires around the screw also is not a great option in both ability to tin heat wire and the solder potentially melting and having the same problem as without of the conductors settling.

    In the past there was a type of both ferrule and washer that would encase the wire within a circle and compress under the screw head. Good option if you can find a source for them. Perhaps Allied Electronic, Mouser or Newerk might have them if you really search. I have seen such a part still available but forgot the source. Such things were commonly used in the past.

    Otherwise you will need a crimped ring terminal to terminate the wire to the screw terminal of the lamp base. Your normal vinyl insulated ring terminals won't work well even with the plastic removed in a high temperature application. Under a lamp base, you must have a high temperature ring terminal. McMaster Carr is a good supplier of them. You don't need the 900°F ring terminals, the 600°F terminals will be fine and you do need them. Dependant upon the lamp base, it will either use 6-32 or 8-32 screws on it - most likely 8-32. Size the ring terminals for the screw stud size and AWG (American Wire Gauge) of the wire. Use of the wrong stud size of ring terminal or wrong gauge of wire in a ring terminal type can come loose on the terminal or allow the conductor slip out in becoming a safety hazzard and in general problem with badly crimped terminals done on the cheap. Due to the design of a P-28s lamp base, you will need to be careful of using a ring terminal due to it’s longer length, larger size and not being able to bend around a more or less curved surface inside the bottom of the lamp base. They were not really designed for use with a ring terminal, and in general one should be careful to ensure the wire or crimp does not get pinched between base and insulator.

    Crimp Tools:
    To crimp any and especially these ring terminals, the standard hardware store bought multi-strip/crimp tool won't do a sufficient job on a steel or in practice any type of crimp terminal. Throw the local hardware store crap away. This especially in the useless "insulated terminalcrimp tool jaws. This is even the case with a overly large tooth of a multi-tool crimp that still more crushes the crimp than displaces material within it. Insulated crimpers just crush the crimp terminal and don't displace the material of the crimp in keeping it similar in size - only the space wire is allowed to be within is compressed around the wire. Very bad connection in general that of a flattening out of the round crimp or wire. In a crushed crimp, some of the conductors towards the edges will have less pressure on them than others. Most hardware store multi-tool strip/crimp/screw cutters are of the badly crimping - much less badly stripping type. Avoid the use of them. Also in leverage you want your crimp jaws to be close to and on the opposite side of the plier pivot for the best use of leverage.
    You will be needing something with a tooth and saddle to it which will send part of the crimp jaw inward into the conductors. Such tools are frequently called "Stakon crimp tools." They have a double or single jaw (with insulated crimper on the single jaw version) and both types have a cutting blade on it's tip. Very standardized type of tool amongst most manufacturers. Klien #1005 and #1006 would be examples of them.
    Proper crimp tension would have a crimped wire you could yank on as much as you want and it won't come loose or break strands to. On a 12/3 cable, you could screw them to a wall and climb the cable without the crimps coming loose. Always after crimping your terminal and while the tool is still compressed pull on the wire to verify that your crimp is tight enough. Always put the seam of the crimp into the saddle of the crimp tool. Crimping the seam with the tools jaw will result in wire that can pull free or be cut. Some amount of practice will be necessary to balance between something overly tight which damages the ring terminal and conductors and a sufficient pressure that the wire cannot come out.
    Of the above #1005 single jaw and #1006 double jaw tools, the double jaw crimp tool works best with 10-12ga. crimps and 18-22ga crimps. The single jaw tool works best with 14-16ga crimp terminals. If you grind off the cutting blade tip, both tools work well with crimping old style Union brand stage pin flag terminals - especially the #1005 type. Any Electrical supply store will have these tools available or know what a "Stakon" tool is as a brand name for a standard type of crimp quality tool.

    Insulating the terminals:
    Once these terminals are mounted on the wires, you should install either high temperature fiberglass electrical tape or high temperature teflon tape over the barrel of the crimp. A roll of 1/2" size three layers thick works well. This will in addition to the fiber insulator under the lamp base protect against shorting. These tapes are 3M normally products - McMaster Carr again as one supplier. This tape - especially the fiberglass tape will both insulate the berrel of the crimp and prevent the fiberglass braiding over the conductor in the terminal from fraying. Width of the three layers of tape should be 3/4" and tapered.

    If possible also while not necessary, install some 1/8" silicone coated fiberglass spaghetti tubing for double insulating over the first three inches of the wires coming off the lamp base. This will both prevent damage due to any abrasion and double insulate for heat where the insulation is hottest and normally melts down first. The McMaster Carr sold - silicone coated fiberglass sleeving - same type of thing as above for a fixture whip but in a smaller size. 12ga tubing would work well.

    Attachment of ring terminals to lamp base:
    The ring terminal attachment to the lamp base needs to have a good contact. If your screw terminals are discolored and in general looking rough, seek replacements for them. Brass screws will be necessary due to heat and conductance. Avoid Phillips head screws for this purpose. It is harder to get them to the proper tension without stripping (especially with a cheap or stripped screw driver), and the amount of push down pressure required to get them tight could damage the lamp base in doing so. Also if not already available, add a silicone bronze external tooth lock washer under the head of the pan-head screw. This will help prevent it from coming loose. Do not use anything other than brass or bronze for a terminal. This especially not zinc plated or even stainless steel hardware for what conducts in a high temperature application. Also do not use chemicals such as even high temperature thread lockers in this area - they will not help current to flow. Deoxident and other types of oxygen reducing or surface cleaning products are okay but not needed in most instances. Often such products will also lubricate the contact which is bad for the concept of a terminal that should not come loose.

    Other screws:
    On the subject of screws, in mounting the lamp base, or in general about the fixture 18-8 at least if not type 306 stainless steel screws, lock washers and nuts are of a major advantage over that of anything zinc plated in a lighting fixture. Should your screws show any rust or discoloring, replace them with Stainless Steel hardware. Otherwise they will tend to rust even more. Stainless will also have less a problem with dissimilar materials connections such as where a steel screw is threaded into a aluminum body. Avoid also black oxide coated hardware inside the fixture, such screws often rust easily. Avoid also nylon insert nuts (nylock nuts), the nylon on them begins to break down at about 221°F which would than prevent any lock nut advantages of such hardware. Instead of Nylock nuts, use side lock or top lock nuts where possible otherwise other types including crown lock nuts. In the case of a screw to nut fitting, do not attempt to use a stainless steel thread deforming nut (top lock/side lock) with a stainless steel screw. Such screws have a lot of surface hardness to them and especially on a smaller screw will strip and break rather than deform the threads of the screw in doing a proper job of locking. Use either a stainless screw with a zinc thread deforming nut or zinc screw with stainless thread deforming nut. An alternative to this would be to use a stainless steel nut with a external tooth lock washer attached to it. This will to some extent prevent coming loose especially when high temperature Threadlocker is used.

    In general for all bolts use external tooth lock washers over any from of spring lock washers, or at least internal tooth lock washers under the smaller size round head or fillister head screws. Much better and distributed gripping power. High temperature type threadlocker is also a good idea in all applications other than to the lamp base electrical contacts. Should your screw head be in direct contact with the porcelain of the lamp base, be very careful not to over torque that screw. Also use a teflon washer or other high temperature padding washer under the screw head for this metal to porcelain contact to prevent breaking or chipping. Round head screws are more commonly used in a lamp base than pan head screws. Be mindful of what type of screw was used and what properly fits within a porcelain lamp base because use of a screw head which is too large such as on a pan head screw while it might fit will either require downsizing of the proper screw or could break the porcelain around it. A 18-8 stainless steel slotted round head screw will be the screw probably provided when new or at least should be the better replacement. On other screws such as the ones to adjust the lamp cap or sheet metal ones attaching the lens train should be observed for corrosion and replaced also replaced as needed.

    Grounding:
    Your fixture if old and asbestos, probably won’t be grounded. You need to install a ground if not already installed or install a new mounting for it if installed in the wrong place. The proper place to attach a ground on most fixtures is to the adjustable mounting plate of the lamp base. Given this part for the most part floats within the fixture due to adjustment needs, attachment to other places will not provide as solid a ground where it is most needed.
    Easy enough to drill and tap for a ground screw the plate that holds the lamp base. Don’t attempt to just toss the ground terminal under something already there for a hole or screw. Normally there is lots of room on the mounting plate to do so. Do not use cutting oil in drilling or tapping the plate either. You want this to conduct and oil will not help in doing so and could pose a fire risk or smoke up your reflector and lamp. On a ground screw, it should not be stainless steel since it does not conduct that well as a material. Zinc is ok but I like using actual grounding screws for them. Hex head slotted thread forming 10-32 x ½" grounding screws such as Raco makes by the hundred pack. The green coating to them both tells what it is and helps them as a surface treatment to conduct. Such screws as yet have not had problems in taking the heat or corroding due to dissimilar materials attached to. Driving them with a 5/16" nut driver is also much easier than driving them with a screw driver. Use a Stainless Steel external tooth lock washer under it’s head also. A loose ground is all a question of path of least resistance in either you or the loose terminal being a better path to grounding out a short. Better to ensure it won’t come loose - ever. In doing this part of the regular maintenance of any fixture should be to verify that you can’t move the ground wire around in it’s attachment. A loose ground wire attachment does not conduct as well. Since your lamp base mounting plate will probably be aluminum, threading the plate for the ground screw can when over tightened or even tightened sufficiently allow it to become stripped. Better to drill thru this and install a top lock stainless steel nut on the opposing side of the ground terminal. (I’m not a fan of rivets for grounds - they loosen especially if aluminum.) As with above for the lamp base terminals, the ground wire should be terminated in a ring terminal. Since this area has less direct heat on it, a more normal non-high temperature ring terminal as long as un-insulated would be sufficient. In this case, a 16ga x #10 stud un-insluated ring terminal.



    Strain Relief Types:
    Your fixture if asbestos probably did not have a strain relief to it’s cap. Instead they used brass grommets most often for each conductor. You now will need to drill out one of these holes for a proper strain relief. 3/8" NPT (National Pipe Thread) - two screw cord grip strain reliefs are the best to replace such things with. Plastic Heyco type strain reliefs tend to become brittle with heat and anything in weather proof rubber grommet grip or other more store bought types in ½" NPT are going to require a 7/8" hole which is a bit large. Make sure that any metal projecting inside the lamp cap will not get in the way of operation of the adjustment or pinch the wires.

    You can use a ½" NPT two screw strain relief as a alternative but it’s not needed in size and will possibly be too large a hole under the clamp unless old style in having a smaller hole shape to clamp the cable. 3/8" NPT two screw strain reliefs are available by way of Altman and their distributers and by way of other suppliers for a 3/16" to 1/4" gripping clamp of 3/8" NPT size. The ones listed in the McMaster catalog are ½" NPT types even if listed as 3/8". They will grip a 3/8" cable but not a fixture whip as well - see below on bulking it up in making do.

    If you buy the Altman strain relief, give it a good go on a soft bench mounted wire wheel. Otherwise the very rough cast = made in China strain relief will have some very sharp cast edges to it. The currently available Altman strain relief also does not have a very good thread class fit to it either. In other words, the nut will be very loose on it’s threads and potentially come loose in the future with use. Use of high temperature thread locker on this to help prevent this problem will help, or don’t use what they offer seek other sources for such a 3/8" NPT strain relief. Another option would be to thread the lamp cap’s hole for 3/8" NPT but only use the beginning few threads of the taper tap so it is a tighter fitting and more close to that of the China crap. Than to use the nut to lock into place the now double nutted strain relief threads. This with High Temperature Thread Locker would probably work well. There are other versions of a two screw strain reliefs if not even two screw/liquid tight grip strain relief combinations available such as for the Altman 2000L Fresnel fixture that are much more refined. They would work well.

    Another option that is oddball and slightly large for the top of the fixture but would work well is the GB brand of store bought - Menards, Romex type flat cable cord grip strain relief. Such a strain relief will be rough cast aluminum and have a rubber clamp that is in a oval in shape small enough to grip your conductors. There is enough rubber on it that it once gripping the cable probably won’t have as much of a problem with being damaged by the heat. This granted a larger hole needed for the ½" NPT threads. Tapping your hole would probably also be a good idea for this strain relief for the double nut technique of preventing strain reliefs with a lesser class of fit (looser tolerance between thread and nut) from coming loose.

    Other types of strain relief used will be the Heyco (there is other brands) line of nylon strain relief. Some will be found on rock and roll par cans in being “liquid tight” nylon. Such strain reliefs - commonly the metric PG-11 size or the ½" NPT size don’t work well with the heat of a Leko. Both it’s screw threads and nut will melt some in becoming loose or brittle, and it’s rubber grip will break down with heat. Two better versions of this type would be the high temperature - grey ones, or the while still normal nylon, Romex/flat cable gripping strain relief. As above, the larger amount of rubber in an oval shape will grip the cable somewhat better grip and be less prone to getting too hot - though in a non-high temperature grip have the other more normal problems. Normal steel or aluminum “liquid type” moisture proof strain reliefs that have a rubber insert in compression that grips the wire such as the Amfi type or Neer will work well when properly sized but be fairly heavy and bulky. They are not much used and in this type of fixture as with the above GB or Heyco types probably not a good solution due to the heat on this compressed rubber gripping strain relief. They all work well on other types of fixture.

    Another Heyco type commonly used on Lekos would be the “Snap in Cord Grip Fitting.” These strain reliefs compress and fold the cord within a two piece relief when inserted into the proper sized hole. The best hole for them is a oval shape not a round hole, though a properly sized round hole will also often work in gripping but not preventing rotation. A slight downsizing of such round holes will be necessary to prevent rotation of the strain relief than. A improperly sized hole will allow the strain relief to pull loose, allow the fiberglass sleeving to slip or crush conductors. Each type of strain relief will have a code printed on it such as 6P3-4 used on a Altman 360Q cap. This designation is important to match for replacements as each determines either flat or round cord and the size of the hole the strain relief is designed to fit in. Check the Heyco website for proper hole sizes to match up with the cord grip used on a retrofit situation. These strain reliefs are hard to work with unless you have the specially designed Heyco pliers to compress and insert or remove them. As above with ring terminals and nylock nuts, nylon becomes brittle when over heated. Replacement of them once removed is frequent. When properly sized, it is a good option and the only one you should not use the fiberglass tape on mentioned below.

    Installation of the wire in the strain relief:
    A trick to doing your strain relief is to coat the end of the fiberglass sleeving over the conductors with a 1.1/2" section of the fiberglass electrical tape at least three layers thick. This should stick outside of the strain relief by about an inch so as to prevent flexing of the wire too close to the clamping part of it that otherwise could cut into the conductors while flexed. The fiberglass also helps prevent against wear at the point it flexes or is gripped. Such fiberglass tape can also be used to bulk up a slightly wider strain relief hole. Installation of the tape should start and finish under the clamp so as to prevent it from un-wrapping.


    Plugs:
    Finally what is not at this point much considered but something to consider is at the plug end of the fixture. First read the instruction sheet that comes with each new plug. Don’t attempt to save the plug that was on the asbestos whip. Not worth your time nor effort. Buy a new plug and read it’s instructions especially where it comes to proper strain relief. You would not believe how many professionals in the industry have no idea beyond safe (Gee as long as the black wire goes somewhere not the ground and ferrule used or not) professional wiring how to finish their professional job by way of doing a proper tension and clamp setting strain relief. Stuff like if using 12/3 SJ cable on a stage pin plug, both strain relief fittings used in the round to really clamp that cable tight. Don’t know how they clamped it all the way down without breaking the plug but once there all the rubber in the wire was once under pressure displaced to an extent only about 1/32" between conductors in the area under the strain relief was left. This area now with a minute amount of insulation between conductors tends to get flexed a lot in potentially cutting thru what’s left insulating them = I would not call that professional given the professional wasting time and money and potentially injuring someone in the future by way of his or her “professionalism” was too professional to read the instructions for proper strain relief or have a thought about over tightening screws or strain reliefs. On a Bates style plug, one insert on the flat and one on the round would be proper for three 16ga heat wires within a fiberglass sleeve. Oterwise, there is a instruction manual to determine what is proper for other types of cable. “I thought” in being wrong by way of too lazy to learn or consider and test or “I was too busy” to do it right should never be an excuse where doing electrical work properly. This even if only on a strain relief. Impossible witout double wire ferrule to fit two 12ga wires within a Bates style plug, much less one cannot fit two cords within it’s strain relief. The Bates plug and it’s clowns is a good design in fitting many types of cable within it. Other types of stage pin, Edison and Twist will take more observation and instruction reading to ensure your cables are properly gripped without being either too lose or tight.

    Read the instructions for installing a plug before installing it = no matter the type. Sometimes if the plug does not include an insert, it will be necessary to add some tubing or friction tape under the plug so as to bulk up the cable. Such a option is fine also. This as long as you can pull the outer jacket of a cable and it is both not loose within the strain relief or pulls out of it, and does not crush insulation between conductors. Always use commercial grade plugs also. It’s not your house so some crap but cheap plug should not be used.

    After this there is a concept of stage pin plug. Twist lock and Edison have clamps that don’t twist wire around a terminal or clamp them directly under the threads of a screw. They are different. If using a stage pin plug, and given you are not using 12ga wire the terminals or ferrules for under the terminal are provided with, you should not be using such things with a 16ga wire. When you install 16ga wires inside a 10ga hole, it tends to have a lot of slack within it and will not crimp or otherwise ensure a proper termination.

    Seperation at this point between crimp type ring terminals and ferrule type stage pin plugs than is necessary. On crimp terminals even flag terminals, 16ga flag type ring terminals are a McMaster Carr type thing as with other 16ga #8 stud type crimp terminals.

    What’s provided with a stage plug is a 12AWG ferrule. This is for use only with 12ga wire. If your fixture is using 16ga wire, it in inserting the conductors under a larger terminal only asks for that ferule to be useless. First because in not encasing the wire strands, they fan out under pressure and settle thus don’t conduct well if not even break. The ferrule itslef in having nothing behind it frequently gets cut thru by the screw terminal attchment. There is an option of folding in half your fixture wire so in a concept of every time you double the size (fold in half a single conductor) the resulting size of conductor will be three sizes larger in size. Thus in the above, were one to fold a 13ga wire in half, it would than be 10ga and not fit within a 12ga ring terminal.

    While ignored, often it will be noted that on a Bates type of plug that the screw will cut thru the 12ga ferrule than proceed in turning tight also cut thru conductors of the fixture wire. That’s a bad thing in both not being able to get your wires out of a plug and by way of cut conductors - higher resistance. Cuts thru the conductors of the wire either by way of the screw or sharp cut edge of the ferrule under clamping pressure

    Just as with a ring terminal type of plug or even flag terminal type of stage pin plug, by way of McMaster Carr, there is proper for the wire used sized ring terminals, there is also properly sized ferrules available. Buy an insulated 16ga ferrule than sleeve the 12ga ferrule over it. This than in having two ferrules resists a cutting trough by way of the screw and in encasing the wire and also being the proper size for the plug’s terminal will fit correctly in a non-damaged way.

    In termination of the plug, follow strain relief instructions - including that detail of not having non-outer jacketed conductors under the strain relief - follow the strip gauge to the plug, and add for a fixture a second properly sized ring terminal, flag terminal or ferrule.

    Some notes amongst many on fixture working on type stuff. Hope it helps, and as one might see it’s not quite as simple as it could be to just re-wire the thing. Good project to work on given supervision once the asbestos part is taken away, but not something to just “have at” in having a few free hours short of having the proper parts and techniques to do it properly. Many more details I am sure I forgot to mention.
     
  9. Radman

    Radman Well-Known Member

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    You really should write a book! I will be referring back to this one for some time.
     
  10. soundlight

    soundlight Well-Known Member

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    OK. I thought that it wouldn't be as easy as I had planned...

    Throwing the fixtures away is out of the question. We don't have any others. All of our fixtures have asbestos whips, and we are a rural public school with little to no budget.

    We have half new style and half old style twist locks, but I would convert to stage pin plugs if I could because of the lower price.

    All of the fixtures have the screw terminals on the outside, with the medium prefocus base. (Except the striplights, which take a standard flood light screw base lamp.) All of the fixtures also have a 500W lamp limit on a tag on the side of the yoke of the fixture.

    So, how much would asbestos removal cost? And, most importantly, how long will it take? I have a dance concert to light in early January, and need to get this project done before the holidays. Also, the drama teacher at my school doesn't want to tell the county because she knows, from experience with other projects, that they will shut us down until they decide that it needs to get done. And then they will take everything away so that we can't use it, and it will take forever to get back.

    I know how to wire one of these things with an new whip easily, and I've got a friend who is an electrician to lend me a nice crimp tool. I've also got the ring terminals. The only thing now is cable and new connectors. The connectors on the FOH pipe are in sets of four, and they are in wall boxes, spaced at regular intervals. There are 6 wall boxes, 4 outlets each, so I would need Stagepin wall receptacles as well as numerous male and female connectors. There are also 4 floor pockets, each with two twist-lock outlets.

    So: our instrumentation:
    25 Century Strand 2331 Lekos
    around 16 Century Strand fresnels
    16 or so Century Strand PAR38 striplights, 3 circuit x 4 lamp(RGB cyc and overhead lighting)

    I've got 102 circuits, hard patched in to 32 channels of 2.4kW lightronics rack-mounted dimmer packs, so I would need 32 female Stagepin receptacles for the wall & floor boxes, and 70 female connectors for the pigtail outputs on the rest of the circuits. I would also need 75 male stagepin connectors.

    To finish up this post: It's my senior year, and I have not really known about lighting design in theory until this summer. So this year, it's a mad dash to get the system out of the dark ages and try to give me a workable setup. And do it all without spending hardly any money at all. I really wish that there was that much desired "quick and easy way out," but that passed when my family decided not to move far enough to go to the school district that had more money. We decided to stay "in the boonies" and keep with our support of this school system.

    Thanks for the help, ship! I really needed some advice on the asbestos deal.
     
  11. tenor_singer

    tenor_singer Active Member

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    I am not going to say how to do this project or what kind of wiring you should use, but I am going to say that you should not even do it.

    I am judging from your signature that you are a student in a high school. You cannot remove the asbestos materials from anything within a high school. You would be stunned at the number of hoops that they have to jump through to have hazzardous materials moved, removed (try being a chemistry teacher and cleaning your lab). This is something that needs to be documented with your building administrator and handled professionaly. There is more at stake here than some old theater lights. There is the safety of your school's students and the building to think of... as well as yours.

    The two primary worries that I have:

    1. If the asbestos is not handled properly, it can sucked into the school's cold air intakes and spread throughout the school. Granted it would be a miniscule amount, but if it is found down the road and traced back to the lights and somebody's improper removal, there will be heck to pay... mostly by your drama advisor and tech director.

    2. If the wire is not installed properly (I was thinking that you should skip the whole SO, SJO issue and go with some form of teflon coated wire) you can cause a fire.

    Here is something you can try if you want to salvage those lights.

    Find local companies that can do this work for you and offer them free advertising in your programs for the year. Some companies may do this as it looks very good for them to donate to high schools (and since public schools are tax exempt, they can document and write off any donation of time and materials that they have done... less the value of your ad space if they take that).

    Please... unless you hold some form of certification this is a job best left done by a professional.
     
  12. soundlight

    soundlight Well-Known Member

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    I can get used lekos for about $90. If I get new fixtures, I would do it through a Kiwanis matching fund program and get 20 people to donate $100. But then I would have to probably do a stagepin conversion. If I was going to have to get all new plugs for the whips, it would probably be cheaper to just get stagepin (five bucks for male & female). I will probably ask my local A/V rental company about asbestos in a hypothetical way and then just kind of explain our situation. Then I can see about getting removal. Then I'll get the hi-temp wire, and get the county to rewire the fixtures. If I actually hand them lens caps, pre-cut wire, and plugs, they should be able to do it pretty quickly. So, I can probably raise enough money to get the asbestos removed, possibly at a discounted price, and then get new whips, mostly county or volunteer work. And then I might be lucky and be able to get some replacement fixtures (6X9's).

    I figured out that my drama teacher has known about the asbestos whips since she took the position (seven years). She said that she didn't want to have her program shut down. I don't want to get cancer from maintaining lights.

    Thanks all.
     
  13. bdesmond

    bdesmond Active Member

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    I'm not touching the technical end of this discussion. Your drama teacher needs to get her head screwed on straight. She's the one responsible for whatever goes on in your theater by the sounds of it, and by knowingly putting students in a position to deal with the asbestos insulated fixtures, she's not doing the right thing IMHO. If I were in the food chain of your district above the school, your drama teacher would be getting shutdown, not the program. I work for one of the largest school districts in the country, and I cannot imagine the operations group ever letting something like this go if they caught wind of it.

    You could liken this to a daycare knowing the windows had lead paint but not wanting to get their business closed. Tough crap for the kids who chewed on the window sill I guess.
     
  14. ship

    ship Senior Team Emeritus Premium Member

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    Brian Desmond has raised some very good points as have you and other posters soundlight in not just this topic of what you can or should not be doing but in general. That of the inequities of life and a necessity get the show on the road verses that of taking a step back from it and doing without that which might kill you.

    I can understand the idea of not reporting or pushing too hard by way of your teachers because it very much might just close down your program. I am of a mid-generation that both worked with the stuff on a constant basis and worked for theaters that officially could not have children in them because of it yet seemed to forget this out of necessity. Asbestos is a huge problem across the theater industry and more especially for schools that just can't afford to best deal with the problem.

    On the other hand given the leaded paint issue as something very simple, it's a wonder why more people turn a blind eye to this which short of chewing on a window sill in some Darwin type of limitation issue, asbestos as something important but ignored more frequently even for those schools that worry about leaded paint. You know, I can't say I ever chewed on a window sill, much less probably held some mercury in my hand, much less have lead weights. While important, it's not as much a concern with me or any future kids of mine as that of asbestos fibers.

    Much less the inequities of eductaion in general that allows for some students to worry about what type of moving light will be best while you in having a lack of staff in being a TD and lack of funds have to deal with a question of what might kill you in the future verses keeping the program running in need of something.

    I wish there were some easy solution or ease in me and others just hopping on a plane to solve your schools problems, but there is not. As a student I also do not recommend you doing any re-wiring of your theater's equipment. This electrician if at all possible needs to head up any such work.

    While your local AV company might have ideas on who might service your gear for you, I seriously doubt they are qualified to do the work for you. They might help fund the project but should not be asked to mitigate the asbestos for you. Instead you might contact the trash haulers local to your area to see what they can do for you in perhaps waving the disposal fees. Even offer up the space for some corporate meeting or proving them as a copany a free show in payment. I'm thinking that your fixtures are not so hard to replace the lamp bases in getting rid of them, the wiring and the plugs.

    On the plugs, twistlock is not so bad as long as safe. One should first probably take care of the real problem, than worry about changing your theater's outlets.
    In running a cost analysis of extension cords, outlets and fixture plugs, verses just new plugs mounted on the new wiring (given you should not save the old plugs with asbestos within them), you will probably find that changing the outlets in the grand scheme of things and for budget is better left as a second phase type of solution after the main problem is solved.

    Keep your eyes on the task at hand and not yet on the overall goals. You have enough problems with what problem you have over adding to it in one fell sweep of all of them.

    In solving your main problem, given you have potential funding taken care of, and an electrician in theory set up to supervise the wiring, I would concentrate on finding a waste disposal solution for the lamp cap, whip and plug of your fixtures. Also for those fixtures such as Fresnels and cyc lights which can't simply have a lamp cap removed easily, this disposal company providing labor in removing as expediant as possible such other fixtures needed to also remove the wiring from.

    I am hoping that in dealing with such gear they will vacuum the fixtures and get them ready for re-wiring by you without the necessity to wear a typar suite and get a tent about your work area. Later discussion would be about cleaning the fibers out from the rest of the theater. Still some form of funding and commercial donation or exchange of service for tickets might be a good solution.

    Than once you get the fixtures secured for the removal, concentrate on new lamp cap and lamp bases and cable and plugs. This is more easy to manage in a budget type of thing.

    I'm thinking that this would be the best solution to your school's problems. The AV company might than be able to get a discount on lamp bases and heat wire for you, and the electrictrian might be able to do the plug type of thing.
     
  15. soundlight

    soundlight Well-Known Member

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    So. Either I shut down my high school lighting ambitions or I shut down the high school auditorium and put my high school on the front page of every paper for a hundred miles. That's the way my dad put it. He's in facilities maintainence.

    The thing with the plugs is that half are old style twistlock, half are new style twistlock, and half of the new style receptacles are so brittle that if you accidentally banged them against the electric while up on the Genie lift, they would probably break.

    Basically, I would be best off just leaving things alone. I'm almost tempted to desert them now, seeing as I'm not going to adjust any of the lights at all, and they're still set for the fall show (definitely NOT a rep plot). And, I'm supposed to do a dance concert in the spring. I'm thinking of having them rent a bunch of par56 tree packages from the local A/V rental house and hook them to our console. I could probably even get a few 6x9's. And as the cyc lights are already wired, I can just patch them in.

    But, the way I see it, if the drama teacher can leave it alone for SEVEN YEARS, and it can come back to haunt her, maybe it will.

    She's leaving next year anyway, so she really doesn't care. She leaves all the tech to me, and acknowledges her forgetfulness. It really annoys me.
     
  16. bdesmond

    bdesmond Active Member

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    From a health point of view, high school lighting ambitions should go on hold until this is fixed. The asbestos fibers are no good for you or your guests. I'm also betting that withina 100mi radius of your school there are people from all of the background ship outlined, and you may be able to work this to your advantage to get all of them to comp or mark down professional services that you need.

    You can still do lighting work without touching the fixtures. Do the design work on paper and school resources e.g. your drama teacher can do the hang and focus with the equipment you have, as it's really not safe or appropriate for you to be doing it.

    Electricians who can install a twistlock aren't exactly hard to come by. The description you've given here leads me to believe that you being on the genie near this stuff is a bad idea in itself as an electrocution hazard.

    Rental gear is probably an excellent idea as an interim solution. Realistically, a spring show is going to go in late March or April, right? That gives you a good three months to mobilize professional resources to take care of the problems at hand and get your theater into a safe working environment.

    All I have to say about that is that if I was the operations team in your district you've given me enough information just in this thread to potentially make your drama teacher's life alot more difficult than it is now. Not giving a hoot because you're on your way out is not the attitude to have in a school. Believe me, I've dealt with my share of the union says I don't have to or it's not my job teachers before.
     
  17. soundlight

    soundlight Well-Known Member

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    My teacher seems to care about everything BUT this. She cares about her shows, and about my college reccomendations, but apparenty not about me killing myself by inhaling asbestos fibers. I NEVER go up on the genie near the plugs when the fixtures have any charge on the plugs. I always go down, and then turn on the light board. I also un-pach any circuits that I will be working on from the hard patch before hanging.

    I think that borrowed gear/cheap used pars/rental gear is going to be the way to go this year for the shows.

    Ya wouldn't believe it. I've been working in the place for four years, and this year I finally have learned lighting design.

    And I can't even do it.

    My teacher doesn't even know how to hang an ellipsoidal, and wouldn't go up on the cherry picker (metal flip-up ladder used to get to FOH pipe) for a million bucks. She could care less if the lights go up at the beginning of scenes and down at the end, with just a warm wash of light. COULD CARE LESS. She's a really nice person, but she just doesn't get this deal at all.

    And either way, my lighting ambitions go on hold. What matters is whether or not I close down the drama, dance, choral and band program performances with me for the rest of the year.
     
  18. AVGuyAndy

    AVGuyAndy Active Member

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    Get them shut down then. Make her care!
     
  19. bdesmond

    bdesmond Active Member

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    I'm inclined to believe that your teacher is more of an acting teacher than a drama teacher, because the manner in which the stage is lit in theater is a crucial component of the atmosphere of the moment.

    I'm glad you're being careful around the aged receptacles. Make sure you inspect them for any signs of the receptacle being cracked or otherwise damaged each time you plug a fixture in or after a run from the heat up/down. When they do crack or get damaged you need to stop using them.

    See if you can get someone who knows how to deal with the asbestos to take the fixtures down and put them in an area which is secure and get them covered with the plastic sheeting to keep the particles in there. This way you don't have to deal with the fixtures when you hang the rental gear.
     
  20. soundlight

    soundlight Well-Known Member

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    The rental gear is going to be on it's own tripod stands. I would definitely not be able to hang any gear, especially since the local A/V company runs off edison connectors and portable dimmer packs.

    If I could get the asbestos whips all removed in a week, then I would be fine. I would do it right after the dance concert.

    I could also get some used fixtures from other places, colleges, local theaters.

    So, how much exposure really matters? Can you wrap the whips with tape or sleeving for a temporary fix to prevent the fibers from spreading while handling the fixtures?

    Thanks all,
     

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