The solutions for these problems are varied.
First with the
strain relief, every time that you change a lamp
base, you should look at the rubber ring to see if it’s still in serviceable condition. Replacing the
strain relief with a better one such as a weathertight one that also uses a rubber ring to compress down on the cable - but a larger one so as not to wear out as fast is an option as is using a two screw
strain relief with some nylon tubing between
wire and clamp. But it’s a
par can and in general not worth that much in parts. Instead adding some weatherstrip adhesive to the threads on the
nut will prevent it from coming loose necessitating retightening it. The less you touch such nylon nuts, the less chance even if heat breaks them down that they will fail with abuse. The rubber ring needs to be under the jaws of the
strain relief or they will dig directly into the
wire and cut it. If that ring starts to get little cracks in it or does not extend under them any longer it’s time at least to replace it. The next improvement to the
strain relief will be in preventing the
wire from flexing right as it exits the
strain relief. High temperature fiberglass electrical tape is rated for it and higher temperatures yet. It will withstand rubbing friction upon it as the cable moves about and prevent the
wire from flexing too close to the
strain relief if it extends past the
strain relief by at least ½". It will also prevent the little jaws of the
strain relief from digging into the
wire. Fiberglass tape at least two wrappings of it will prevent the cable from breaking down after it exits the
strain relief and prevent any heat from transferring between the
wire and it’s
strain relief. The only trick to remember is to end that wrapping of the tape under the
strain relief or it will come loose.
PAR Cans for our use pose a problem for us. We use them both for old style ray lights and normal GX-16d or EMEP (Extended
Mogul End Post) lamp bases as used on a
PAR 64 lamp. The old style ray lights were not yet designed to slip into the EMEP lamp
base and necessitated female to male quick
disconnect terminals to attach between them and a
cord that’s also used for a EMEP lamp
base or to swap out broken lamp bases. Our EMEP lamp bases were cut short on the wires feeding them than fitted with similar receptacles to make them universal with ray light lamps or even a
ACL (aircraft landing light) lamp using screw terminals. In other words, due to a frequently breaking lamp
base that is normal to other than Osram aluminum frame protected lamp bases, the
porcelain only lamp bases of the past frequently broke and needed replacement. Since all cans had one of three types of lamp it, they needed to be used with the quick
disconnect terminal in the only solution for them as a junction between the
cord and what ever type of lamp
fitting it was to use.
So over the years, the company I work for came up with a nylon female 0.25" quick
disconnect terminal terminating the ends of the hot,
neutral and
ground wires off a
cord. The
ground I’ll explain later. Nylon while rated for the same temperature
rating as vinyl and
PVC at least does not melt as easily when it gets hot. It becomes brittle which is not good but at least no conductors are instantly exposed. I’m not a fan of the
system but it has been in use many years. The male disconnects are from AMP and have large covers over the
terminal allowing the nylon to cool on both sides of the splice thus to some extent keeping them a touch cooler than normal
crimp style insulated terminals. Crew chiefs like such a
system because 30 feet up on a
truss, they can lean over and with one
hand replace a broken lamp
base with a similar set up one. You do not have to attempt to remove an entire
lamp cap or fish wires
thru the
strain relief. The
Leko prep people like the
system because all lamp caps are universal between the three lamp types used.
They attached #8 stud to quick
disconnect tabs to the screw terminals of the low
voltage lighting
ACL lamps which would adapt from a screw
terminal to a
crimp type quick
disconnect female. On the lamp
base, they used Amp brand heavy duty male disconnects and covers to go into the female insulated
terminal on the
feeder wires. And on ray lights, they used the same
system. Simple and easy no matter what lamp is used in a can. Also since there were terminals on the wires, the cords were easy to remove in
fitting the cap for a series wired
ACL bar or replacing the
cord.
Problem is that nylon only has a operating temperature of 180 degrees F. Should any insulated parts of the
disconnect touch the lamp, much less with time and heat, it cracks and becomes brittle if not melts. Not something you want inside a can and they constantly needed replacement. Than there was those that did not realize that the amp quick
disconnect required a special
crimping tool and that unless you used the proper Klien/Stakon
crimp tool for even the normal female
crimp it would come loose. In other words, in addition to the terminals breaking down, they frequently came loose from improper installation. The
system was universal for various lamps but a maintenance hassle. In switching over to the new
system it was important to convince those that would nay say that the two major hustles in being broken lamp bases was fixed by a new style of them, and that the second most common problem - the splice was what was being replaced. Given both you no longer had to replace the lamp
base. This is an on-going retraining program for the tech people that are used to quick disconnects inside a can. Decent idea, but not rated for the temperature any better than the
stock par can parts.
We stopped buying replacement VDE grade
fixture wire for
par cans. Sure it was a direct replacement and frequently even better than what came with the cans, but still not something that would last. Better types of 200c heat
cord such as Suprenat Heatzone
wire are on the market and are far superior to the Euro crap that comes with
par cans, but they are cost prohibitive for a bulk low tech
fixture. Instead, since a lamp
base can be bought with a 40"
whip, why not just use the heat
wire leads coming directly off the lamp
base? Given new style ray lights that have similar lamp bases to that of a
PAR can, just using improved lamp bases less easy to break and with the long leads would be the solution. A
ACL lamp since it’s low
voltage needs to be wired in series. Given that, and the less heat it’s going to be operating under - not used as much amongst other things, than such lamp caps should be wired directly to the lamp bar anyway and not need to be mixed in with normal cans that can go lamp bar or independent. Given enough lamp caps to do both, that’s the solution. That’s given new ray light kits. If no new ray lights, than extra care needs to be taken with a quick
disconnect and they should be kept to a minimum amounts in
stock with nylon
crimp terminals. That’s my solution until the ray lights wear out. There abouts of 2/3 of them are already on the way to the trash due to melted wires out of the lamp
base. The replacements will fit in cans without quick disconnects. Unfortunately, there is still about 100 more
PAR 64 ray lights to go before they can be replaced.
That’s the solution I’m changing to at the moment. For lamp bases, I still have some old style non- aluminum frame types in
stock and of them they all get a tension test. Any lamp
base that does not have sufficient retaining pressure to
pick up a lamp by the lamp
base is tossed into the trash. Too much chance that lamp
base would come use in transport causing problems at a gig. Any with broken parts get replaced to a
point. The quick
disconnect is also tested for tension.
The rest are all aluminum frame type lamp bases that are protected from abuse and in general seem to last longer. Those are perminatly wired to the
cord. Some of the
stock retains a quick
disconnect terminal between lamp
base and
cord for use with either ray lights or old style
par cans, but in this case at least now I’m using a non-flammable nylon female insulated
terminal. It’s not rated for any higher temperature but hopefully will not become brittle as easily. The male terminals are the same given tech people working on them know about the proper AMP
crimp tool, but all wires feeding male or female terminals because the fiberglass braiding has problems with unbridling, have been fitted with high temperature
heat shrink to prevent the fiberglass from coming loose and becoming unbridled at the
disconnect. This means there is no chance the
insulation over the
wire will become exposed also. Any
wire with fiberglass coming loose or breaking down at the lamp
base - especially on old style ray lights, have been either fitted with
heat shrink also or been taken out of service. Amazing how the
wire on ray lights seems to melt as it comes out of the lamp
base but such things are old and better off replaced.
For some reason in something like 20 years of cutting the 40" leads down to about 10" nobody threw out the heat
wire from the
par cans. I have boxes upon boxes of
par can whip heat
wire. As I re-wire lamp bars, the ray light - series wired lamp bars get wired with that extra heat
wire running between the bar and fixtures. The wires are now terminated in high temperature steel ring terminals so they don’t require any work ever. Lap caps are permanently mounted to the bars and all you have to do is
bolt the rest of the can to a bar. Quick disconnects in addition to melting down have this problem of loosening up with use. Do away with them and you have a more dependable
fixture.
As said, some of the more normal
PAR fixtures are kept in old style so as to be used either with old style ray lights or can fixtures. No more than say 100 of them as there would not be use for more than say 100 ray lights at any one
point. Such fixtures have the old heat
wire cords on them terminating inside the can not in a
porcelain terminal block but with a improved flame resistant quick
disconnect, and it’s fibreglass braiding is held together at it’s stripped end by high temperature
heat shrink. Stuff that takes a blow
torch to shrink down. For the moment, we are only using normal black fiberglass
wire shield over the conductors on the
cord. Eventually we will
switch to vinyl or silicone coated fiberglass
shield as it is showing premiss with other fixtures in being abrasion resistant. For the moment also we are using the
Heyco strain relief - I have hundreds upon hundreds of them in
stock and can easily replace what breaks down. But the improvement to both is the use of fiberglass electrical tape over the fiberglass
insulation to prevent the
wire from breaking down where it is clamped down upon and flexing too close to it. This helps a lot.
For the
plug end of such fiberglass insulated
cord, since it’s 16AWG
wire, 16awg ferrules are used with 12ga ferrules over them. This double
ferrule both retains the shape and proper clamping pressure on all strands of
wire but also brings the
wire up to a size that the screws on a slip
plug will properly clamp down on. For non-heat
wire, stuff that’s 16AWG, it can be folded in half than installed into a 12
AWG ferrule in making it into a 13
AWG piece of
wire with a fold to it. This fits well. Any
wire when doubled up equals a
gauge of
wire three sizes larger than it started out to be. Double up a 18ga
wire and it equals 15 ga. Since heat
wire is tinned it does not fold that well and a dual size of
ferrule is best.
At the
plug’s
strain relief, when I’m doing them,
friction tape which is not flame resistant and cannot be used directly on a
instrument, but can be used on a
plug is used. All tape when put on fiberglass is best off wrapped around the
wire some, than the fiberglass slipped over the wrapping, than the tape wrapped over the fiberglass for best use. This forms a layer of tape that prevents the wires from bending too close to the
strain relief and with tape above and below the sleeving prevents that sleeve from slipping out of the
strain relief. Otherwise, others at the shop use heat
wire with fiberglass shielding on a
Bates plug with one
strain relief fitting flat and one rounded. Works adequately.
The heat
wire and fiberglass
insulation over it has the advantage of being able to touch the
instrument without breaking down. It is not very damage resistant however. To some degree if little abrasions or cuts develop on fiberglass it can have adhesives such as Plyobond smeared on the cut and it will seal it up and prevent it from opening it up further. Otherwise at least like with all other fixtures, fiberglass needs to be replaced with time. No big deal and at least it’s not a question of the cheap semi heat
wire lamp cord cracking and exposing conductors with exposure to paint or
fog. Switching to the above silicone or vinyl fiberglass shielding will help prevent all problems.
For the
ground wire, since fixtures used to be swapped between all three types of use, the
ground used to be installed with a stud to quick
disconnect terminal. Basically it’s a 1/4"
flat section of metal to fit into a female quick
disconnect crimp terminal with the other side of it having a hole for a #10 screw that gets mounted on the can. They used to
rivet them to the
fixture with a 3/16"
rivet. Things were never tight enough and always came loose. Than the quick
disconnect with use, even if it made it easy to remove the entire
whip assembly, started to loosen up in addition to the
rivet coming loose. You are much better off with a
ring terminal permanently installed on the
fixture’s cap. I use Stainless steel 10-32x3/8" hex head screws with stainless steel top lock nuts. The screw uses a 5/16"
nut driver, the
nut uses a 3/8"
nut driver. Very easy to install with the proper tools and the nuts being a top lock type, they won’t come loose. Nylon lock nuts have the nasty habit of melting down or not retaining when in a high temperature environment, top lock nuts use a deformed thread to prevent coming loose. Stainless steel screws while slightly more expensive are a better option for use in fixtures especially at electrical connections for them.
Because it’s the
ground and not going to get as directly hot, high temperature ring terminals while they would be nice are not necessary. It’s also not going to matter if they are insulated or not. Should they be insulated types, big deal some
insulation melts off the
ground. For
wire, I use a lower temperature
wire. I use silicone FEP / type K 150c heat
wire for the
ground on a
par can. As opposed to type SF-2 fiberglass braided silicone heat
wire used for the lamp bases or normal heat
wire that’s rated for 200c, in this case I want the
ground wire to melt down first should there be a heat problem. Lots of vent holes plus a big opening in the rear of the can. Should not be a heat problem, but if there is, seeing a melted down
ground wire would be a good indication - better than other conductors failing. This will give an apparent sign there is a problem in the
wire, plus it’s the
ground, if nothing else, this can be melted. (Normal building
wire such as type
THHN or even a rubberized
cord such as SJOOW will have a operating temperature of 90c and should be avoided for
fixture use. Type VDE is not rated but must be somewhere in the range between 100 and 150c on the outside.) On larger wattage fixtures such as a Mole Light, I use the above SF-2 heat
wire for the
ground and type TGGT fiberglass insulated Teflon 250c heat
wire for the conductors for the same reason. Good stuff, not very flexible but holds up well to heat. When using such TGGT
wire, since it’s rated for over the temperature of the high temperature
heat shrink, fiberglass or Teflon electrical heat tape is required in it’s place. The FEP
ground wire is also much smaller in overall circumference of the
insulation which allows for a smaller size in cable bundle when coupled with a few layers of heat tape when going
thru the same size of
strain relief.
So out of 114 fixtures, I wired up 60 of them plus another 24 with the old
system of using a quick
disconnect between the lamp
base and the
cord. The rest used brand new 40" lead lamp bases that were wired directly to the
plug. We had a surplus of pre-wired lamp bases and I had to keep a certain percentage of
par cans wired in the old style. Otherwise for the remaining
stock of
par cans, about 50% of the cans now have the new style lamp
base directly wired to the
cord. Basically it’s quick
disconnect terminals were removed and a high temperature
butt splice was crimped to the heat
wire. Over the high temperature
crimp was put high temperature heat shirnk. The stuff sells for like $24.00 per four
foot section of it but is well worth it. It’s also supposed to seal up the space between
wire and
heat shrink against moisture making it more safe yet. Old cords on all fixtures have been removed on all the upgraded fixtures. Crew chiefs complain they can’t hang from a
truss above an audience and replace the lamp
base with a free
hand to which I reply that with the new style lamp
base and removing the disconnects that are the parts that fail, you no longer need to replace them. Other cans are being switched to new fiberglass whips and better quality quick disconnects. All
ground terminals are directly bolted to the frame using the above method and sealed beam lamps -
ACL bars have their lamp caps and wiring perminatly mounted to the bar.
That’s at least what I’m doing with
par cans that’s a
bit different. Quality after market lamp bases are the key to being able to do this. New ray lights would remove the need for quick disconnects but at least with them still in service they are watched and better installed. Still searching for a high temperature quick
disconnect but I have high hopes for the
current flame resistant
disconnect at least at the moment. At some
point I will also stop buying fiberglass shielding sleeving for over the
wire use and
switch to at least vinyl if not the more expensive silicone. This will make a
whip that does not need to be replaced at all.
One final improvement that I did not come up with but approve of is that between the
barrel of a
C-Clamp and the
yoke we install a fiber washer. The fiber washer acts as if a metal washer but in being a cardboard like thing does not allow the
fixture to be tensioned enough to the clamp that you still can’t move the
fixture on the clamp with one
hand. In other words, the fiber washer acts like a ball bearing in allowing you to swivel the
fixture by the
yoke, yet allows for enough tension on the
yoke that it will not move about on it’s own. All our fixtures get these custom cut for us washers. One
hand to swivel the
fixture is all it takes - a good improvement on fixtures.