# Melting Twistlocks



## BenjaminD (May 23, 2007)

My highschool auditorium hasn't been maintained in a while, and we have a bunch of twistlock sockets (on pigtails) melted to the plugs in them. Have any of you encountered this problem before? 
Why does this happen? Is this just a case of Abused 20 Year Old High School Auditorium Syndrome, or is it something I can prevent? 
What is the best way to fix this (I have been using a hammer and destroying the connectors too damaged to open). 
Ben


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## Jezza (May 23, 2007)

If you don't actually "twist and lock" the connector, you can inadvertently create an arc between the barely connected pins inside the connector which will melt the connector. 

Also, if you overload the connector over 20A, your breakers should trip, but if for some reason they don't, the connector might be the next place to release the energy. 

I wouldn't be taking a hammer to the connectors. Just doesn't sound like a good idea. I would attempt to unscrew the twist and lock from the cable if possible and remove it that way, or cut the pigtail and put on a new connector. Unless your fixtures are twist and lock as well, put on female stage pin connectors on and make your life easier.


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## soundman (May 23, 2007)

Something is very wrong if the plugs have melted together. It could be casued by several things not limited to pulling more amps through them then they are rated for or a loose conection that has caused some arcing. If it were my space I would pull the dimmers for the affected circuts and cut the pig tails. If there was enough heat to melt the plastic plugs there is a fair chance that the insulation is shot. Replacing the pig tails completly would be best.


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## soundlight (May 23, 2007)

I had some of those at my HS. They were on the sockets that I was running 1800W through, and I think that (even though the cable and connectors were rated for above what I was pumping through them) there was some sort of short inside the connector due to lousy wiring that melted the plastic.


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## BenjaminD (May 23, 2007)

Jezza: The connectors are too badly melted to unscrew. That's part of the problem. The socket and plug are melted together, and they're both melted enough that I can't undo them without a hammer. I have no idea if they were locked, originally... they were probably hung over 10-15 years ago (there is enough dust on the fixtures to grow a small garden. I'm cleaning them... slowly.... 

Everything in my theatre is twistlock. I wish we had stagepin, but we just... don't.

soundman: Due to the fuses on the dimmer (never blowing) vs the rating of the plugs, I don't think they could draw enough power to melt the connector. Actually, it might be a loose connection... except that I've found 6 connections melted together. It's possible that a previous TD didn't understand the concept of twistlock, but unlikely. 

I'm scared/worried about this because it creates sparks (like when you hot-plug a fixture, except they don't go away. I caught one doing it today, I noticed the fixture behaving erratically, and went down to check it out, and discovered the connector was buzzing and occasionally sparking. And the screws holding the connector together were slightly charged(!). I flipped out, of course, (and replaced the plug and socket) but what if I hadn't noticed?

And how on earth can you replace a pigtail without removing the entire electric/batten assembly?!

soundlight: most of these channels are for striplights, not loaded over a KW... Again, I'm not sure of the intelligence of previous electricians/TD's/random people that would install plugs


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## icewolf08 (May 23, 2007)

It sounds to me like what you need to do is check every plug on every fixture and every plug-in strip/raceway. Make sure that all of the wiring is attached securely and correctly to each connector, and replace any that have any signs of damage (chips, cracks, charring, scorches, etc.). This could turn out to be a costly and time consuming project, but it will be totally worth it, not to mention that it is a safety issue.


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## rmarston (May 23, 2007)

Been using twist locks forever - no problems. Souinds to me like an impedance problem in the connect / plug - that is if they are not being loaded beyond their rating. I bet there is loose connections on one or both sides of the connection - resulting in meltdown.


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## Charc (May 23, 2007)

Edit:

Read Ship's post, next page.


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## icewolf08 (May 23, 2007)

Twist lock connectors are not unsafe (when installed correctly). The Key-Out twist lock connectors (I always forget the code numbers) are not supported under the NEC as I understand it, but the Key-In connectors are NEC compliant. I wouldn't quote me on this, but I believe that is true. There are still many theatre that use both kinds of twist lock connectors, and there is no reason to change everything to stage pin if you can fix/replace parts with the same connectors.

ADDITION:
Key-IN Twist Lock: L5-20 is NEMA compliant. below is a photo of one from altman:



Key-OUT Twist Lock: non NEMA compliant. below is a photo from altman:


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## Edrick (May 23, 2007)

Being that your theater isn't anchient but it isn't brand new what is some of the equiptment you have for lighting and sound? Being that I'm the first person to go through the first year at our new high school I can only wonder how it will be 20+ years from now.


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## BenjaminD (May 23, 2007)

I'd love to go all stage pin, but I simply don't have the funds. This year was the first year we had any kind of budget, a grand total of fifty entire dollars. I can beg the school to get me lamps and they usually will. Other than that, I really don't know. And when I do start bringing up saftey issues, our flysystem is first on the list. We do use the key-in connectors, and they should be (and have been) alright except for a few that, apparently, were installed/connected incompetently... resulting in unsafe conditions. 

But I'm glad to hear that this isn't "normal," and that this problem could be alleviated if I checked every single plug and outlet for correct wiring and made sure they got a good connection every time. 

Rickblu: I have a strand 300 board (24/96), and two strand CD80SV racks. I have about thirty very old strand lekolites, 16 or so strand 6" (750 watt) fresnelights, and 8 or so 8" (2 KW) strand fresnelights, and four 3 circuit/12 cell strand strips, and four 4 circuit/12 cell strand strips. Oh, and 8 2-cell cyc wash units that look far better pointing at the stage than the cyc. Our real problem is drapes... they look atrocious. Sound, we have 2 QSC 1000 watt-per-channel stereo amps, and an old 24 channel mackie mixer. Most of our mics decided to walk off (before I go there), we have one corded and one wireless SM 58 and a bunch (5?) of strange audio-technica handhelds with rather disgusting pickup pickups. I have no clue what the mains speakers are, due to the nasty fact that you need a full body harness to get to them safely and I'm not stupid enough to think that I can use a rope to climb down onto the ceiling surface that couldn't support me anyway (annoying!!) Our booth monitors are driven by a Crown 200 WPC amp, but they're both dead and I replaced them with a very, very strange combination of speakers that actually produe decent sound. We have peavey 15" monitors (x4) driven by 500 WPC QSC amps. All in all, we're fairly well off. Excepting those times when you have to resolder half the com system to repair damages done by kids skipping in class, when used condoms fall from the loft (which I recently padlocked), or when plugs start to fuse together.


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## ship (May 24, 2007)

He he he, about what was it 20 or 30 years ago were this a post, someone will have said twist lock as modern instead of stage pin. Twistlock is the “get into the current days” reality for when the theater was wired and there is absolutely nothing wrong with it. In fact, a twistlock stage has certain advantages over that of a stage pin stage including plugs not coming undone by way of gravity and experience in splitting the pins. This much less, experience in knowing how to wire a plug, it’s simpler to get a standard twist lock properly done than that of a stage pin that takes crimp terminals or ferrules properly applied and often not done properly.

Sounds unsafe and planning a work stoppage ha? Time based upon your experience with real life to learn from it and make the best of it over avoiding it. On a personal note, did you ever study why stages at some point went twistlock, why it’s in many ways very safe and even if it were Edison plugged safe and code compliant? Before getting on a high horse about refusing to deal with what you get the chance to experience, understand it that fix it. Running away and stomping one’s foot don’t help.

I would on twist lock plugs rely upon the rattle test of the plug. A twist lock or even Edison plug shouldn’t rattle when you shake it. You hear a rattle, you know some screw terminal is loose. This as opposed to stage pin plugs that have extra tolerances and do tend to rattle if you shake them, a twist plug won’t rattle if in as a broad concept safe condition.

Follow this up with the why a plug might get hot. Imagine a bunch of strands of wire under load. That’s the theater aspect, now add the science aspect of expansion and contraction and you now at times get a wire loose within a plug. This looseness causes resistance to current flow which results in heat. Don’t worry - also happens at times on stage pin plugs, much less the reverse of this where by something is overly tight and it also causes resistance to current flow.

Simple enough concepts I would expect overall. Simple enough to also inspect each time such a plug is used as opposed to on a stage pin plug where used that they would make noise in a rattle test at least after innitial install where the strands of wire settle down due to heating in often also making for stuff that gets loose with age. Overall sounds fine to me, just needs some TLC. Too bad in being a top talent you would refuse to come back until you get what you feel safe.

I would recommend a thorough reading of Edward Gordan Craig for background in such concepts.



charcoaldabs said:


> Am I the only one who thinks this guy should get ride of every twist-lock connector, and replace them all with stage-pin connectors? Am I wrong in thinking that is standard for today's theaters? Bring your theater into the present 21st, start with the safety issues. If (this is a school, right?) the administration doesn't give you money, I'd grab the guy (or gal) who doles out money and bring him down to the theater. Show him the buzzing connector with sparks. Tell him you need money above and beyond your current budget to update a safety concern. Tell him if he doesn't appropriate the funds, you'll hold him responsible for any problems or accidents caused by the faulty connectors.
> I don't know anyone else, but as a student, I'd refuse to work under those circumstances. From the way you've written it, it just sounds plain unsafe.


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## SHARYNF (May 24, 2007)

Time and time again I see where people with very little experience look at something and immediately jump to the it's not safe, I'm not going to deal with it.
Equipment needs to be maintained, and part of TECH in many cases is finding these problems and fixing them. Things break, get worn out or go bad, it is part of the system, it is part of things working and aging. It could be any number of things like Ship said or corrosion or somebody not properly twisting the connector. It is really pretty common. 

Sharyn


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## BillESC (May 24, 2007)

If it sounds like you have a cricket inside the connector.... it needs fixing.

All to often this is a symptom of a loose compression fitting. Over time as Ship alluded to, the actual screw terminals of connectors loosen which raises impedence, causing arcing and hence heat. You would be well advised to annually inspect every connector and tighten the compression fittings.


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## soundlight (May 24, 2007)

BillESC said:


> You would be well advised to annually inspect every connector and tighten the compression fittings.



If only high schools had the budget and personnel to do that. If I had asked the school system's elec maintenance department at my HS, they'd probably laugh. "You want us to inspect over 200 connectors that are giving us (as the maintenance dept) no problems so far? Who are you kidding?"


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## Lightingguy32 (May 24, 2007)

soundlight said:


> If only high schools had the budget and personnel to do that. If I had asked the school system's elec maintenance department at my HS, they'd probably laugh. "You want us to inspect over 200 connectors that are giving us (as the maintenance dept) no problems so far? Who are you kidding?"


A good sampling during an annual maintenence call would be to disassemble and inspect about 2 conntectors per electric per 10 circuits. this way you get an idea if some one has been wiring something right or wrong and what kind of shape in general the connectors are in over that one electric or through out the whole theater. I tested this technique before and it yields results that are pretty accurate. (actually i kind of invented this method)


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## soundman (May 24, 2007)

soundlight said:


> If only high schools had the budget and personnel to do that. If I had asked the school system's elec maintenance department at my HS, they'd probably laugh. "You want us to inspect over 200 connectors that are giving us (as the maintenance dept) no problems so far? Who are you kidding?"




I see no reason wh this can't be an in house job by the theatre students. Fixing cable will prep them for there first few years out in the real world.


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## avkid (May 24, 2007)

soundman said:


> I see no reason why this can't be an in house job by the theatre students.


*With* proper supervision of course!


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## BenjaminD (May 24, 2007)

Rattle test? That sounds quite ingenious. And definitely less time consuming than taking apart every plug in the place. Especially if I too apart a plug every circuit or four. 

Sharynf: I agree, fixing broken things is a very, very major part of tech. Particularly unsafe broken things. If something sparks, it obviously needs to be fixed, immediately. I was merely wondering why it would happen and if it was normal. 

I will probably have time to check the outlets and plugs during the first week of the school year (teacher planning week)... But thank you all!


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## Charc (May 24, 2007)

Don't want to hijack this thread, but after my stupid post on the previous page (now edited over) I'll hang my head in shame and make a post here.

I got a bunch of lengths of cable, with no ends (correct specs, this isn't extension cable from wal-mart.) and I got a bunch of SPC connectors. All this was left over from the renovations of the theater. I really want to make use of all this extra cable, but I'm hesitant to work on anything that'll have electricity flowing through it. What do you guys think about it?

(Notes about myself. Not wired anything for the theater before. Have done some minor electronics projects before, but nothing of this caliber. Student.)


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## icewolf08 (May 24, 2007)

Charcoal- first off, everyone is allowed to make mistakes. Even professionals do.

As for your wiring project, does your school have an electrical shop, or shop or tech/ed. program with a teacher who is knowledgeable in electrical work? If you do, talk to them to get some help. I doubt that people here on CB will tell you how to wire your gear for liability reasons. If your school doesn't have someone you can go to then call your local dealer/repair/rental shop, they might be able to donate some time for you to come in or for someone to come out to you and show you had to do what you need to do. In other words, get some professional help/supervision.


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## Charc (May 24, 2007)

icewolf08 said:


> Charcoal- first off, everyone is allowed to make mistakes. Even professionals do.
> As for your wiring project, does your school have an electrical shop, or shop or tech/ed. program with a teacher who is knowledgeable in electrical work? If you do, talk to them to get some help. I doubt that people here on CB will tell you how to wire your gear for liability reasons. If your school doesn't have someone you can go to then call your local dealer/repair/rental shop, they might be able to donate some time for you to come in or for someone to come out to you and show you had to do what you need to do. In other words, get some professional help/supervision.



Closest thing I've got is the maintenance department. I'll check 'em out soon. Otherwise I'll probably forget about it. Academic year is over in under two weeks.


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## lightbyfire (May 26, 2007)

BenjaminD,

One other thing to keep in mind if you are going to work on the female connectors on the pig tails. You need to manually trip the breaker in the dimmer rack. This is always a good idea, but particularly in strand CD80s which have trickle current running through them, even when the channel is at 0. 

Also, try making friends with the facilities people in your school, help them out and they will help you. You can also find out who is in charge of low voltage safety, they will understand your issue and likely help, theatres are just as much a part of your schools electrical infrastructure than any other outlets.


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## BenjaminD (May 27, 2007)

When I'm working on the pigtails, I trip everything in the rack (and have my little voltage-sensor-beeper-pen-thing with me to check everything before I touch it). I have a tendency to be overcautious (if that's possible). 

I know most of the school maintenance dept. They're very helpful and friendly when I need to borrow mops, drills, etc. But I'm rather afraid to let them near the dimmer racks. Even the district electrician didn't really know about them, and seemed very suprised/leery of cleaning them, which makes me worry about them touching them at all, I don't want them damaged by someone who knows nothing about them. 

I'm very glad to discover that this isn't just something that happens randomly, thank you all very much!


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## gaffer240 (May 28, 2007)

One thing I did not see in this thread is the reason the fitting inside the plug get loose. I believe it is the 60 cycle hum from the AC electricity. Aside from looseing the clamps in a twist lock they also will cause lights that are on a long running show to lose focus. 

In my case loosen the nuts and bolts that hold my electrics grid together (60'X40' TV studio grid). In some lamp sockets it can cause enough of a problem to cause the pins of a lamp to arc and weld to the scocket. 

Loose plugs can cause the plug to overheat when the contacts arc rather then transfer electricity evenly across the contacts.


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## icewolf08 (May 28, 2007)

gaffer240 said:


> One thing I did not see in this thread is the reason the fitting inside the plug get loose. I believe it is the 60 cycle hum from the AC electricity. Aside from looseing the clamps in a twist lock they also will cause lights that are on a long running show to lose focus.
> 
> In my case loosen the nuts and bolts that hold my electrics grid together (60'X40' TV studio grid). In some lamp sockets it can cause enough of a problem to cause the pins of a lamp to arc and weld to the scocket.



If your AC hum is that bad that it is loosening bolts in your grid I think you have a serious problem. There really shouldn't be enough vibrational energy coming from your electrics to do that. I think you might want to look into seeing how your HVAC system is laid out around your grid and see if that is causing the vibrations.

Now, on SCR dimmers you often run into issues with "singing filaments" but this is due to the way the SCR chops the AC cycle That square edge on the wave can cause the filaments to vibrate and "sing", but I have never heard of this affecting anything really. I can see where it would affect the bench focus over extreme periods of time, but chances are in a 2-3 week run of show, the hang and strike of the fixtures is more detrimental to the bench focus.

AC "hum" also should not cause arcing in your lamp bases. If there is some serious vibration going on, you can get a bad connection, but if it were the AC power that was causing the problem I think more people would have exponentially more problems like you describe. I would have your space checked out.


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## Chris 757 (May 28, 2007)

I have worked for the Virginia Beach City Schools for about 10 years. I have seen this problem a lot. The repair work that you are describing needs to be done by an electrician - your profile says you are 16, so I am assuming you are a student. Your school should have a electrician available to them for such repairs. You should let your teacher or principal know about this problem. If it is not done correctly you can have a fire or hurt yourself. Please *do not* try and fix this yourself.


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## len (May 29, 2007)

A good shop will take apart the connector on every fixture and cord, and tighten them. I see it getting done every January, when things are slow. It's better to do it at the shop than at the show. And if there's that much dust on the fixtures then it probably hasn't been done in years, so a thorough troubleshooting and cleaning is in order. 

As for 2P&G or twist or edison or whatever, most places I've worked at tape the connections, except for twist. They feel that a twist lock is the only one not needing a taping, so logic would say they believe twist to be the best connector. Not saying that's definitive proof, but that's what they think.


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## gaffer240 (May 29, 2007)

icewolf08 said:


> If your AC hum is that bad that it is loosening bolts in your grid I think you have a serious problem. There really shouldn't be enough vibrational energy coming from your electrics to do that. I think you might want to look into seeing how your HVAC system is laid out around your grid and see if that is causing the vibrations.


Talking small scale problems. When you have say 30,000 watts on day after day, year after year, there get to be small problems here and there. In our facillity the HVAC is shock mounted and isolated from the studio (or so they tell me).

In addition all our circuits are on pigtails creating even more isolation.

I do not believe that you can completely discount AC hum. I was always taught that it created vibration, though small, that over time will loosen things. My experience seems to support this.

(side note: the grid is ares pipes laid out in a 4'X4' square patern with bolts at all intersectionsin.)


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## ship (May 29, 2007)

gaffer240 said:


> I do not believe that you can completely discount AC hum.



Sounds just logical enough that I'm going to have to use it as the next attempt to do something to the new guy...

Already had an Assistant Shop Manager going to Menards to get some checkerboard paint, and the head of Leko Dpt. going to moving lights repair for a arc lamp pressure test kit, and others searching the building for an ID10T form, I now have a new concept in gaming with people. Back in the military there was the cans of elbow grease and muzzle flash, and as a carpenter there was the sky hooks and board stretchers.

AC 60Hz doesn't have anything to do with bolts loosing tension or fixtures falling out of focus. Air Conditioning, sound systems, expansion and contraction, wiggling about on the grid etc. all can play a factor, AC power is not a factor. Also most modern lamps are designed to prevent the filament humm.


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## ship (May 30, 2007)

Just for point of reference and I have a ton of "modern" stage pin plugs as with other plugs on my wall of shame in a similar melted condition no matter the type and especially 60A stage pin. Here is a top of the line "Bates" plug that had a wee melting problem due to a screw that was a wee bit loose. Get the idea that twist lock plugs are just plugs, what goes wrong on them is not due to their nature, just due to their maintaining.


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## photoatdv (May 1, 2009)

We have stagepin and we probably replace 1-2/ major show on average (So like 5-10 a year) because they start melting. It is generally high resistance creating heat on one of the connections within the plug. We had one that melted the two plugs into a giant blob (still worked believe it or not-- we found it right before a show and didn't have a spare on site). Biggest issue we have with replacing them is that it's a huge pain to get to our dimmers to turn them off. By the way are you sure that the Strand CD80's have a current at zero? Pretty sure ours don't (Our TD thinks he's indestructable-- and I have to admit he does the craziest stuff and has never gotten hurt other than some minor scratches and a couple (okay well a few more that a couple) of shocks, but how many techs haven't been shocked on occasion).


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## jonliles (May 1, 2009)

I don't care who you are. Getting shocked is no fun. If it is a portable pack, I unplug it. If it is a pigtail, I trip the break, then I put a zip tie through the breaker so no one else can energize it. I may be a bit over sensitive, but I've seen a couple of electricians die (non entertainment related) from forgetting to do the simplest of things - ISOLATE THE ENRGY SOURCE. I work with industrial power plants - those OSHA reports are not fun.

My daughter's school has the same issue with 20 yo stage pins. The county electrician said "they're fine." Regardless of what the coutny electrician says, I isolated the circuit (tripped and locked out circuit) & removed the plug to prevent future use. Supposedly, this summer the theatre is being renovated under "SPLOST."

Footer can chime in about our county's maintenance practices.


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## chieftfac (May 1, 2009)

Just Finished 6 days of "Benching Fixtures" (after two years) All cleaned, shined, plugs checked (twist loc), Strain reliefs checked, ... surprising number of loose wires into those plugs. Those screws really do work themselves lose over time...(only about 18 in 178 fixtures, but still!!) All I can say is MAKE the time to go over your equipment... It is so nice to hear a touring group compliment you on the professional state your space is maintained...


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## epimetheus (May 1, 2009)

I can comment on the 60Hz AC hum. I design high voltage substations with power transformers rated for over 3000A. Those babies hum. With the range of current you see in most theater branch circuits, you're not going to have physical vibrations. 60Hz vibrations are mostly limited to transformers anyway.


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## venuetech (May 5, 2009)

the previous posts have plenty of solid information that i shall not repeat

Learning how to take care of your cables/connectors is what you need to do. so it will serve you well to read all the instructions that come with the new connector. If you have any questions be sure to ask the school maintenance guys. be sure to get the strain relief done right 

State/local codes may be the determining factor on whether you can convert to stage pin. So you may wish to look into that before you leap. 

Once you get the past twenty years of failures replaced, then you can start lighting the show.

you may want to keep some spare connectors/plugs around as you never know when you might need one.


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## MircleWorker (May 5, 2009)

I second Ship


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## teqniqal (May 6, 2009)

If you have fasteners coming loose in your pipe grid, look to see several things:
Are the bolts and nuts and washers grade 5 or stronger (three radial lines on the bolt heads -- nuts and washers are harder to figure-out)?
Are there lock washers under the nuts?
Are the bolts / nuts torqued to spec with a torque wrench?
If 'no' is in any of the answers, therein may lie your problem.


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## Chris15 (May 6, 2009)

teqniqal said:


> If you have fasteners coming loose in your pipe grid, look to see several things:
> Are the bolts and nuts and washers grade 5 or stronger (three radial lines on the bolt heads -- nuts and washers are harder to figure-out)?
> Are there lock washers under the nuts?
> Are the bolts / nuts torqued to spec with a torque wrench?
> If 'no' is in any of the answers, therein may lie your problem.



Does not the grading refer to tensile strength?
Can someone enlighten me for the need of a tensile strength in a washer? I can understand the bolt for obvious reasons and needing a high grade nut to mate also makes sense. The washer has me stumped.

Lock washers are not normally needed if Nylocs are used.


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## epimetheus (May 6, 2009)

Chris15 said:


> Does not the grading refer to tensile strength?
> Can someone enlighten me for the need of a tensile strength in a washer? I can understand the bolt for obvious reasons and needing a high grade nut to mate also makes sense. The washer has me stumped.
> 
> Lock washers are not normally needed if Nylocs are used.



I think the grade of the washer has to with it's resistence to deflection. The whole purpose of the washer is to distribute the force. If it bends too easily then the force will be localized to the center of the washer, which is the same as not having it there at all. At least that's my theory until somebody corrects me. Also, I prefer a spilt lock washer, or even better a Belleville, over a nylock. I've have too many bad experiences with nylocks galling up on me.


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## ship (May 7, 2009)

epimetheus said:


> I think the grade of the washer has to with it's resistence to deflection. The whole purpose of the washer is to distribute the force. If it bends too easily then the force will be localized to the center of the washer, which is the same as not having it there at all. At least that's my theory until somebody corrects me. Also, I prefer a spilt lock washer, or even better a Belleville, over a nylock. I've have too many bad experiences with nylocks galling up on me.



Ah' there is a wealth of questions in asking. Cone or Belleville amongst them or was this designed for lock washer, zinc or bronze if any lock washer at all. Cone, Belleville, serrated or not, internal, external, or spring lock washer in being it's own subject beyond ferrules and or expansion and contraction or strands of wire and wire type in stranding type settling.

As said, whole wealth of concepts.

No threadlocker at least in concept if in theory conductive type.


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## TimMiller (May 7, 2009)

hey charc, if you wanna come to town i can show you how to fix cables. I have a whole bunch, stage pin, twist loc, pin & sleeve, cam, edison, xlr, and dmx to fix. If anyone else is in houston or around and wants to learn let me know. If you want to hook up some sub panels, transformers and run a crap load of EMT PLEASE let me know. I have more projects than i can handle. Today i learned i can overload the neutral conductor feeding our shop causing the voltage to jump to 150 then do one heck of a nasty power sag right after.


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## teqniqal (May 7, 2009)

Yes the hardness of the washer has to do with it's ability to 'stay flat' under stress. Here is a picture of a non-hardened washer under load:


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## frostgfx (Jan 28, 2011)

My new touring system of conventional lights (mostly) is cabled with SOOW 12/3 and L5-20 twist-locs. I have always come up with a routine maintenance plan for my model trains, climbing/rescue equipment and now my lighting system. 

Being a touring system for rent, you as the owner of the equipment have a responsibility to your rental clients to provide them with safe fixtures and equipment. I recently had to rent some lights from another local vendor and their fixtures didn't come with safety cables... go figure.

If you have a large system, you can break it down into... say a dozen fixtures to PM, or a dozen cables to check both ends for loose connections, signs of arcing, etc. While you check the electrical connections, you can check things like lense cleaning, lubricating yoke handles, checking for the presence of gel frames, safety cables and bulbs.

When it comes to dealing with 3 Phase power, I feel it better to pay a licensed electrician to check that over. Anything on a truss, flybar, etc. I am happy to check over on a ladder with fall protection.


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