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Conventional Fixtures PAR 56 ground wire

Discussion in 'Lighting and Electrics' started by Radiant, Aug 1, 2008.

  1. Radiant

    Radiant Active Member

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    We use PAR 56s for house light, cheap ADJ brand, and they are giving me many fits. I've been replacing the sockets as needed, as the insulation flakes off rapidly. But now I'm seeing several that have absolutely destroyed ground wires - insulation burnt off, tarnished green copper, frayed and broken strands. The ground wire has a round lug on the end, held to the can by a bolt and nut. The bolt and nut are locked together so tightly that I can't unscrew it. I don't have this issue with the 2 spare cans that were never installed in the ceiling. I end up just ripping the bolt out of the flimsy aluminum can. I'll post pictures tomorrow, as I'm going to rewire a couple more.

    I have two questions. Firstly, what in the heck is making the ground wire corrode like that? I understand the insulation flaking off - they're cheap cans, and I'm accustomed to their short lifespan. But I just don't understand the copper wiring being in such awful condition.

    Secondly, I want to make sure I replace the ground wires correctly. I salvaged some high-temp wiring from a half dozen 360Qs I rewired a few months ago. Tonight I bought an assortment of ring terminals - I think the wiring is 16 AWG, but my bases are covered if I'm wrong. And I bought 6-32 x 1/2 zinc coated screws and nuts. Does this seem appropriate? The sockets are Sylvania 36" whip, sheathed in Production Advantage's Flex-Guard FPE sleeve.
     
    Last edited: Aug 2, 2008
  2. Footer

    Footer Senior Team Senior Team Premium Member

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    Is it humid? Your in Oklahoma, so there is no ocean near by. How long is the light on a day? Whats the conditions like?
     
  3. Radiant

    Radiant Active Member

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    It's pretty humid these days. Oklahoma sees the effects of all four seasons - hot summers, cold winters. I'm not too sure how long the lights are on during the week. I'd wager that some days they're on for 12 hours, other days not at all. They are mounted to the roof structural beams. We've long had heat issues with them.
     
  4. JD

    JD Well-Known Member

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    Two things:
    1) Metal + Heat + Humidity = big time corrosion! Also why the screws won't come out.
    2) I suspect these are mounted vertically and therefore the heat builds up at the top where the wiring is.
    Replace your sockets with something like these: PAR-1 PAR56 PAR64 Mogul End Prong Lamp Socket (Sylvania / Osram)

    They come with a 36 inch whip. If you are cutting off the wires and only using the base (not recommended) then the left over wire is defiantly high temp. A better solution would be to not have any connection in the fixture, and just use high temp Teflon or silicon with fiberglass sheath. The less connections the better.
     
    Last edited: Aug 2, 2008
  5. TimMiller

    TimMiller Well-Known Member

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    I have learned that crimp terminals will melt in pars quite easily. I found some high temp insulated crimp terminals a while back that were rated for 150 deg C. In which the aluminum will probably begin to warp first. But the standard home depot stuff does not hold up. I once had a can that someone crimped and then wrapped the crimp in e-tape, well the thing got hot and melted the crimp and caught the e-tape on fire. Its not good to have a flame comming out of one of your cans on the DS truss.
     
  6. Footer

    Footer Senior Team Senior Team Premium Member

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    Just blame it on the pyro guys...

    12 hours a day... ya, you might want to invest in some higher quality cans from the get go. The ones you purchased are meant to be on for a few hours a day, max. Put in high quality whips, and that should help ya.
     
  7. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Heat; and galvanic action among dissimilar metals. Aluminum can, Electro-tin plated terminal, copper wire, and whatever the material(s) from which the nuts and bolts are made.
     
  8. Radiant

    Radiant Active Member

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    Rats, now I need to learn metallurgy too?!?! I thought mine would be an uncommon situation due to the severity, but apparently not.
    [user]JD[/user], you are correct, they are dead hung straight down. Heat has been an issue with these cans from day one. Literally, glass lenses were separating from their reflectors before the installation was complete. And those are the very whips I got, too.

    [user]Footer4321[/user], a few years ago I learned, firsthand :oops:, about electrical tape in PARs. (Had one go up in flames at a wedding rehearsal, the flame didn't go out after the breaker tripped, and it was inaccessible without a ladder.) I wish we could get better cans, along with many other things, but the budget is what it is.

    Here's what I ended up doing today. I rewired 3 PAR 56s and one PAR 64 this way. You can see in the end of the can where we've ripped open the air vents to allow more circulation. Let me know if this passes muster.
    [​IMG]
    [​IMG]
     
  9. Footer

    Footer Senior Team Senior Team Premium Member

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    Your still going to have issues with the plastic melting. The air vents will help, but your going to have issues. They do make terminators without the plastic, or you could remove the plastic. Grounds don't need to be insulated.
     
  10. Radiant

    Radiant Active Member

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    Good call. I'll snip off the plastic in the future.
     
  11. JD

    JD Well-Known Member

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    Yep. Just cut the plastic off. You might also want to put a star washer under that nut, although in a fixed installation it's not as big of a problem. Odd can, with the bulb mounted from the front. That braid wrap doesn't look like fiberglass. Could be a problem if it is plastic. Hard to tell if the ground wire is Teflon, but it looks like it. (Shiny, bend radius, etc.) How are those feed-throughs holding up? I've seen them used a lot on the China cans, and haven't seen any melt yet. I figure that if they're going to melt, you would have seen it as those cans look like a hot box when the lamps are in.
     
  12. Radiant

    Radiant Active Member

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    I got the sleeves from Production Advantage. They're flame retardant polyester. Seems like appropriate stuff to me. I'm not sure what the insulation is on the ground wire, but it outlasted the TP-22 base it was attached to, without any noticeable wear. By feed-through, do you mean the tension relief? They seem ok, no melting so far, though one of the cans I pulled today may have an issue. I couldn't tell if the tension relief, the cord inside it, or some electrical tape melted. It was moderately goopy. Assuming it's not reusable, where can I pick up a few of those? (Other than my growing pile of dead PAR cans?)

    I hate them! I've griped before on another thread about them. How well do you trust PAR can lamp retaining rings? How well do you trust safety screens, when the OEM lamps drop their lenses? And besides the shoddy Chinese cans, the installation is exceedingly lame. There's no plug on the end, they're butt-spliced to the power cable, which is usually hanging in the air 10 feet or more. Instead of springing $6 for a clamp on each, they riveted all the yokes in place. So to replace and refurbish one of these overheated, insulation-eating things is a good 30 minute job.:evil::evil::evil:
     
  13. ship

    ship Senior Team Emeritus Premium Member

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    Normally the wiring to the fixture is only a 90c wire - easily with use overheats, becomes brittle and flakes off when moved. If you have that problem with the ground wire you also have it with the conductors which is dangerous. Often a fixture cooling thing - for me it’s always a question of how such a thing got its UL listing in that I never use 90c wire near a lamp over at most 100 Watt - if even then and if then its fiberglass sleeved.

    None the less, I prefer to see my ground wire go bad before I see a conductor go bad - good indication of something bad with the others to correct. Something to also look at is the rubber gland part of the strain relief - it don’t take heat that well also and once brittle, the little teeth of the plastic strain relief often do terrible damage first to outer jacket than conductors in cutting thru them with use.

    The ground screw is what it is - metric, probably varnished or some sort of thread locker to keep it in place, no worse than a riveted ground in both not so sufficient in how I do stuff.

    Possible the ground wire has been touching the lamp and over heating but normally ground wires are fairly short in going direct to the ground screw.

    Good you are using the Sylvania PAR 1 socket - best on the market in my opinion & bypassing the barrier strip - another common problem with cans for patching the 90c wire into the socket is often another point of failure. This especially with screws coming loose or screw tension or tension of sharp edges of screws clamping down on the bare strands of wire instead of ferrule covered strands.

    So now for your conductors, you no doubt have a fiberglass sleeve coated 200c silicone wire which goes out the strain relief (you check) by way of outer jacket #0 fiberglass sleeve to the plug. Only improvement there - after if necessary changing strain reliefs when the rubber fails is to perhaps add a dual wrap of #23 fiberglass electrical tape around the outer jacket fiberglass sleeving to prevent as it were chafing at the strain relief. The sleeving prevents cut thru, prevents the whip from flexing as tight an angle at the strain relief and in general is a good thing. Just a bit of it overlapping the strain relief by about a half inch for a one inch width in a dual or tripple layer (ends of the tape inside the strain relief.)

    So you have a straight run of the power conductors to the plug, only a question of what to do on the ground. This ADJ type screw and or the other brands that rivet their grounds to the can often are problematic in that while they are not persay loosening (It’s metric by the way thus why it might be stripping on you), but the ring terminal on them in combination with the softness of the aluminum might allow the ring terminal to get loose. Always a good thing to check on safety inspection - can you turn it?

    Replacement of the ring terminal - typically a 8-32 screw for a ground is preferred. 6-32 is undersized. Never use Nylock nuts inside a lighting fixture - the nylon of the lock nut has an operating temperature I believe I remember maximum of 175F, and after that it’s much like the jacket of the 90c wire in becoming brittle and or not functioning as designed. Never also use thread locker on the threads of a conductor - they reduce conductivity. Also, black oxide coated fasteners in coating don’t conduct as well and often also tend to corrode with heat and moisture. Stainless don’t conduct as well also but does take the heat really well, plus has a harder rating.

    For the ground screw, I tend to in general use an actual grounding screw. Them green 10-32x5/16 hex washer head screws. Easy to figure out what it is, its coating helps conduct, easy to install given a 5/16" head when used with a 3/8 hex head of the nut. Two nut drivers tightening the screw as opposed to questionable tension able to get with a slotted or phillips screw driver. All sorts of screw type in the ground screw, I prefer those that are thread forming instead of thread cutting because of the nut used. I typically use a 10-32 18-8 stainless steel top lock nut with such a ground screw or if necessary for conditions an external tooth lock washer attached zinc plated steel nut. With the top lock nut - sometimes the ding in the threads is not sufficient - toss such ones out, don’t attempt to use them if they don’t sort of stall while installing them. Same concept with the screw, once used with the thread deforming nut, do not re-use once removed.

    Should you use zinc plated steel toplock nuts - which might also be fine, toss them also after first use in being a bit softer than stainless. This is a concept for electrical connections or fittings in general though not to say for normal fasteners in say having a 1/2-13 screw and side or top lock nut. A bit less thread deforming going on with say a 1/4" screw than with a #10 screw but milage might vary also in noting that a deforming screw is in a way stripping its way onto the screw thus by way of deforming it, kind of stripping it in a way. Something to keep an eye on with both nut and fastener in tension as similar to that of a nylock nut in telling when its bad. Loose enough to hand thread, bad. In doubt toss it, but in general = the Stainless Steel nut of a ground screw combination will often be fine for a second use, the lower grade screw will be toast.

    General concept in doing small screws with thread deforming nuts. Often good to do a harder class with a softer class or at least two of the same class - normally really bad to do two harder class in the same bolt combination. Normally say for a 1/2" bolt - hopefully at least, you are using a Gr.5 screw with a Gr.2 nut. Normally you are using say a zinc plated screw with a stainless steel nut. Can use the reverse but should never do stainless with stainless = they don't thread well. This as similar to say doing grade 5 with grade 5 in thread deforming - they will just tear themselves up. Don't attempt to do a thread deforming screw in #6 size unless a brass screw at most. Just too small against the resistance to work dependably unless hardened or stainless screw with normal zinc plated gr.2 nut. Instead, better next best option would be a nut with external tooth lock washer attached for high temperature applications or that of a normal nut with added lock washer. Side lock nuts are as similar to external tooth lock washer lock washers in general better but if all that's available... it's a good thing in being better at least for high temperature conditions than a nylon insert nut.

    But as with any nylock or other type of lock nut, that’s a good thing, but do add a external tooth lock washer to the mix to keep it honest. External tooth lock washers have more gripping power than internal tooth ones one would use only in situations where the head of the screw or nut is not sufficient to take advantage of the gripping power of the washer. These types over that of a spring lock washer any day.

    Frequently I’ll do two external tooth lock washers, one under the head of the screw, the other directly under the nut, but at least one under the nut is a good plan. I normally use zinc plated steel external tooth lock washers for a ground, silicone bronze for high heat for a conductor otherwise especially under a brass screw. If desired, a thread locker coating, varnish coating or glue can be added to the threads after the connection is done but not before. Shouldn’t be necessary but can be done.

    On ring terminals, vinyl coated ring terminals - see above with nylock nuts have the same temperature rating. Vinyl as opposed to nylon has a melting and or flame point rating the same and as opposed to becoming just brittle and flaking off might become liquid plastic inside the fixture. That’s doubtful but if you want, either get un-coated ones or grab insulation and ring terminal into two sets of pliers and yank the coating off. For a ground a normal believe its zinc plated copper ring terminal is fine to use. For higher temperature/lamp socket installation only use high temperature ring terminals however.

    The insulated ring terminal has its uses in keeping together any fiberglass or jacket on a conductor where its stripped but otherwise the above high temperature tape can be wrapped around barrel of terminal/sleeving of the conductor joint in holding all that together. Three wraps is fine. This especially might be important if you have a SF-2 fiberglass coated silicone heat wire ground wire in use where it’s going to fray where stripped otherwise.

    Not commonly available but can be dipped / dyed this SF-2 to be a ground wire. For the ground wire however in following the above concept of I want to know when I have a problem with my main conductors with heat, I often will do 150c Type K, FEP wire so it melts down way before a conductor will. This much smaller FEP also allows me if I wish to use a much smaller size of fiberglass sleeving over jacket such as 1/4" or say a #2 vinyl coated in size. Often such a solution if not just the vinyl coated sleeving helps prevent against wear on the sleeving.

    Otherwise FEP or SF-2 be it braided or without in Teflon or silicone is fine for a ground. Could go 18ga for the ground on a PAR 56. Could also go 18ga of the lamp socket also but the stock 16ga PAR one socket is fine overall. Quite a few PAR 1 sockets manufactured and available with different wire gauges and coatings plus wire lengths.

    Finally on the crimp tool. Remember just as with wire rope clips to “never saddle a dead horse”, with a crimp, never put “the seam into the saddle.” This means that on a “Stakon” type crimp tool that has a jaw and a recess side, never put the seam of the crimp where metal is bent together into a tube shape to hold the wire into the side that gets the jaw. Seen it way too often even coming out of factories and they always fail. For this gauge of wire, a Klien #1005 would be correct as an example. Also, don’t use crimp tools that crush instead of displace material. Note on the jaws of the above #1005 tool there is both the rounded tool part and the tooth jaw. Don’t use the rounded jaw ever - all it does is smash which is useful for prepping or rounding out a 1/16" wire rope crimp to where you want it before the Nicopress tool but otherwise for our business fairly useless even with insulated crimp terminals. All you are doing is smashing the terminal - it still has the same circumference overall. Such a “insulated terminalcrimp jaw relies on the concept of a less strands per conductor wire such as THHN building wire that don’t persay give as easily as a multi-strand conductor that like grains of sand can settle about and under current and expansion/contraction settle a bit more. The jaw displaces material within the crimp terminal thus compresses the overall size a conductor will have room to settle into. Always good to use the jaw just make sure its not putting the jaw into the seam of the crimp or its toast.

    Further, once the crimp is on, leave the tool there and tug with the tool on that crimp hard. This will tell you if you have sufficient pressure - a thing of practice and leverage - often one leg of the tool setting on the table while the palm of your hand pushes on the other side. This concept especially useful for high temperature terminals.

    The right tool for the ... Should you be concerned about the jaw having displaced material thru an insulated terminal, some electrical tape, heat shrink or high temp tape over the barrel or insulation of the terminal will sufficiently insulate over the exposed area. Much better to have a good crimp than to worry about a recess in it that could short should something get into the hole. For a ground... grounds are supposed to be the path of best short so un-insulated is fine.

    That’s my solution for doing a ground. Green grounding screw in 10-32, s.steel top lock nut, a external tooth lock washer or two and a properly crimped ring terminal. This plus the FEP.
     
    Last edited: Aug 4, 2008
  14. ship

    ship Senior Team Emeritus Premium Member

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    Sounds like its own repair type situation on a post. Sorry must have missed it.

    (1) Not such a fan of poly for a sleeving, the open weave for me seems to snag and un-weave at its ends more easily. A small snag in fiberglass sleeving can be glued back together if not too large with "Plyobond" (see McMaster Carr.) The poly is toast.

    (2 - 3) See my notes on the rubber insert and yes you can replace them - believe it's normally a Heyco type PG-11 size and readily available from all sorts of suppliers. There is also a grey high temperature version available.

    (4) Electrical tape is not rated for the temperature of a lighting fixture - that goopy goo is the glue on the tape breaking down in no longer holding tape to what ever the heck it was being used to reinforce or insulate. This much less it's now a flame or smolder hazzard. See my note about 3M Scotch #23 or 69 fiberglass high temperature electrical tape for a better solution for high temperature applications.

    (5) Hmm, that's a code problem. Nuff said.

    (6) Not sure what this means, I tend towards screws where possible on yoke to fixture, yoke to its mounting... hope they area at least steel rivets with rivet washers but even than.... yea, that's probably not such a good idea. Are you meaning some sort of lamp bars with a fairly large rivet or grommet fastening the fixture to the bar, this much less with wire feeding thru? Not my preference but in code compliance that could have been the solution. By code officially you are not supposted to say have a pipe that both has the wiring running thru it and fastening bolts for individual fixtures passing thru it = hmm, something about someone not looking in forcing that bolt thru the pipe and shorting wire to frame of an often not even grounded bar other than by way of the fixtures and hopful suffucient enough mechanical ground.

    Ways to do this, can't officially recommend a solution other than if UL listed for what it is, it is what it is and doing otherwise will de-list and un-insure it from any liability the manufacturer will have over it. Bad thing to take it upon yourself to "improve" should someone get injured by way of your work. Is what it is and as long as if I expect a lamp bar as opposed to individual fixture...

    This taking for granted it's a lamp bar of sorts you describe.
     
  15. ship

    ship Senior Team Emeritus Premium Member

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    So you went to all that trouble of doing high temp. crimp terminals and wrapped like 60c electrical tape around them ha? Somewhere I think your research into the total package left something to be desired.

    Ring terminals in par cans don't melt that I have seen - either over pressure on the metal or the vinyl melting do you mean? Tried removing the vinyl?
     
  16. ship

    ship Senior Team Emeritus Premium Member

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    Zinc plating on a screw and other plated materials don't have a problem with aluminum - plain un-coated screws perhaps. Copper wire shouldn't be directly touching the can. Ring terminals are plated I believe with zinc in being rated for both aluminum and copper. Stainless steel don't conduct as well but also never has a problem as I believe silicone coated bronze. For the ground screws stuck, normally they are the black metric equivolent of black oxide but not - its a coating but nor as porus in retaining ability to rust or I think resistant to conducting. I think it more a sort of varnish coating on them afterwards to be a thread locker or perhaps low quality screws in stripping and or standard/metric tool use in getting them out. This plus did I mention if Phillips and low grade screw, and the user of the tool removing it without sufficient pressure and a quality tool easy to strip and or not be able to remove?

    galvanic action is less a real problem these days with materials than supposed. Something to be aware of in noting what materials you use or combine but not something to be overly concerned by.
     
  17. ship

    ship Senior Team Emeritus Premium Member

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  18. ship

    ship Senior Team Emeritus Premium Member

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    Could be any number of reasons for this be it bad/used lamps in new sockets in trashing them to a fixture less used / or snagging on stuff.

    Used to have a fixture with that sort of jacket, was find for years but it was not used much, had a few others that instantantly snagged. All snag of course, and as only my opinion, these snag easier.

    For prevention of snags, vinyl coated fiberglass sleeving is the best though some nylon closed weeve sleeving I recently bought seems to also be holding up really well. Even a heat shrink nylon sleeving I'm currently play testing.
     

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