Running standard AC extension cable near LX

[FlashBang]

Hi all,

So I've started adding movers to my LX, and have the issue of getting non-dim AC to them. My current way of doing so is with an extension cable in a regular outlet at stage level, tie-wrapped to a conduit that runs up to batten level, tie-wrapped to the slack portion of the dimmer power feed (I have motorized winches for my LX), and then left loose at the end of the batten near the dimmers. I then run another extension from batten-end to fixture when necessary.

To date, I have only used the movers for small perfomances where not many other fixtures were used and the total show ran less than an hour.

I am worried that running a standard extension cord near my fresnels at full power for 2 hours would be hazardous. Are my worries valid? If so, what is the appropraite cable to use?

Thanks.

 

[gafftapegreenia]

If you are using standard hardware store "orange cord" it is likely 14/3 or 16/3 SJTW. Normal "extension cord", be it black, orange, green, yellow, red or what have you uses a thin thermoplastic jacket that is not acceptable for stage use. You should be using type 12/3 SOOW. You could use 14/3 or 16/3 SOOW, depending on the wattage of the movers, but I would stick to the standard of 12/3 SOOW.

Any cable, even SOOW, should be run in a way that it avoids touching a lighting instrument. SJTW will melt, whereas SOOW will have a much shorter lifespan.

I see you are in Montreal. I'm not sure of your fire codes but I'm not certain if my fire marshal would approve of "portable" cable being installed in a more permanent manner with tie-wraps.

Another option, depending on your dimmer rack, is to swap out some dimmer modules for a relay or constant on modules. You could then a power a mover from any existing circuit in the house that you choose.

 

[MNicolai]

First I'd look into what gaff suggested -- whether or not your modules are swappable. If you can give a dimmer rack model name to us, we can tell you if they are.

The second thing you should do is make some adapters for your existing cable inventory. If you simply don't have any 12/3 SO-type cable, you'll want some, but if you have a bunch and it has stage pin or twist-lock connectors, then make or buy adapters between those and 5-15 connectors (aka "Edison" aka "household"). You need not buy lots of new cable if you have a few 50' stage pin cables laying around. You can adapt from 5-15 on the front end of the extension (near the receptacle), then adapt out of it on the back end (near the fixture), and repurpose a cable you already own on an as-needed basis.

If you swap modules so that you have constant non-dim power from your existing receptacles, you'll also probably need adapters out of that and into 5-15 to connect to your fixtures.

I'm making a few assumptions here, so it'd help if you gave us more info on what your dimmer racks are and what your existing cable inventory looks like along with which style of connectors you use on your lighting fixtures.

 

[sk8rsdad]

Your AHJ would be the final authority on this but assuming they adhere to the CEC, the use of SO or other extra-hard duty cable would be required in a theatre. SJ cable may be permitted by the local AHJ.

Depending on your dimmer rack, it may be possible to replace a dimmer module with a relay. That would be your best option.

 

[rochem]

The second thing you should do is make some adapters for your existing cable inventory. If you simply don't have any 12/3 SO-type cable, you'll want some, but if you have a bunch and it has stage pin or twist-lock connectors, then make or buy adapters between those and 5-15 connectors (aka "Edison" aka "household"). You need not buy lots of new cable if you have a few 50' stage pin cables laying around. You can adapt from 5-15 on the front end of the extension (near the receptacle), then adapt out of it on the back end (near the fixture), and not need to buy tons of new cable.

Agree, swapping modules is probably the best option, but if that doesn't work, I'd propose a slight amendment to Mike's solution. Assuming you do have the spare stage pin/twist lock cable lying around, instead of simply building adapters for each end, I would actually recommend putting different connectors on the ends of the cable. For one, this will be cheaper because you only need to buy one of each gender, instead of two of each to build adapters. Secondly, having different types of power running through cables with the same connectors can get dicey. When using 208V power alongside dimmer circuits, it's standard practice to have all the 208V cabled with twist lock connectors, and the dimmers cabled with stage pin, to avoid accidentally plugging in the wrong one. While mixing up non-dim and dimmable 120V power isn't nearly as big of a deal, it still might be good practice to keep the connectors separate so that someone doesn't accidentally plug a mover into a dimmer, or a conventional into the ML non-dim circuit.

 

[skienblack]

A lot of people have recommended using constant power or relay modules if his rack is allowing. We actually have had serious problems with this. We are using an old D192 rack and built some non-dim modules by bypassing the SCR on the tray. We have had 3 of the MLs we powered off that configuration have power supply issues. One was a ETC Revolution and two were HES Studio Colors 575. The best we can figure is the banks of dimmers were causing power spikes upstream of the dimmer tray. Something to think about.

 

[Grog12]

A lot of people have recommended using constant power or relay modules if his rack is allowing. We actually have had serious problems with this. We are using an old D192 rack and built some non-dim modules by bypassing the SCR on the tray. We have had 3 of the MLs we powered off that configuration have power supply issues. One was a ETC Revolution and two were HES Studio Colors 575. The best we can figure is the banks of dimmers were causing power spikes upstream of the dimmer tray. Something to think about.

I would think that the problem here actually lies in the fact that you built your own non-dim modules. If you'd purchased non-dim modules for your rack and had the same issue then there might be something to it.

. When using 208V power alongside dimmer circuits, it's standard practice to have all the 208V cabled with twist lock connectors, and the dimmers cabled with stage pin, to avoid accidentally plugging in the wrong one. .

On 120v twistlock the ground is reversed from 208v twistlock. You'd have a hard time plugging one into the other.

 

[porkchop]

A lot of people have recommended using constant power or relay modules if his rack is allowing. We actually have had serious problems with this. We are using an old D192 rack and built some non-dim modules by bypassing the SCR on the tray. We have had 3 of the MLs we powered off that configuration have power supply issues. One was a ETC Revolution and two were HES Studio Colors 575. The best we can figure is the banks of dimmers were causing power spikes upstream of the dimmer tray. Something to think about.

The difference is that some dimmer racks have specific modules that are made to provide constant power. ETC's R15AF and R20AF modules for examples. I don't know anything really about D192 racks, but if you built non-dim modules I have a feeling they weren't designed by the manufacture to provide on/off non-dim power.

 

[skienblack]

I would agree that it was an inherent flaw in our design besides the fact that it merely takes the power from the bus bar through the breaker and into the choke. We built these because we could not find any constant power or relay modules for the D192.

 

[BGW]

I would agree that it was an inherent flaw in our design besides the fact that it merely takes the power from the bus bar through the breaker and into the choke. We built these because we could not find any constant power or relay modules for the D192.

You shouldn't have the choke connected if the SSR is bypassed. I'll bet that's your problem. D192 racks are cool, I wish we had one.

 

[rochem]

On 120v twistlock the ground is reversed from 208v twistlock. You'd have a hard time plugging one into the other.

That's exactly my point. The whole principle behind the design of the L5-20 and L6-20 connectors is to ensure that you can't accidentally plug something into the wrong source. This same principle could be applied to the OP's situation in order to help ensure that only conventionals get plugged into dimmed circuits.

 

[Grog12]

That's exactly my point. The whole principle behind the design of the L5-20 and L6-20 connectors is to ensure that you can't accidentally plug something into the wrong source. This same principle could be applied to the OP's situation in order to help ensure that only conventionals get plugged into dimmed circuits.

True. My immediate thought though upon reading your OP was that there are still many twist lock houses in the world.

 

[LavaASU]

Agreed. If you're trying to essentially use the dimmer as a 20A breaker, you shouldn't have the choke connected.

 

[derekleffew]

...We built these because we could not find any constant power or relay modules for the D192.

It might be noted that the non-dim option from the factory for the Colortran Dimension 192 dimmers was a small PCB card with a slider switch that sat on top of the SSR. It didn't actually bypass the SSR; instead turned it into an Off/ON-but-chopped-waveform device when control signal crossed the 50% threshold.

... I am worried that running a standard extension cord near my fresnels at full power for 2 hours would be hazardous. Are my worries valid? If so, what is the appropriate cable to use?

What exactly is the concern? As stated already, the heat of conventional fixtures is a issue with any cable used near them, whether or not it contains dimmed or un-dimmed power. I'd be more concerned with dressing the data cable away from the fixtures.

 

[gafftapegreenia]

It sounds like OP is running Edison cords to use 120 volt power on his movers. 208 isn't a worry here.

OP is obviously smart enough to know that his movers need constant AC and that dimmers at full isn't appropriate.

Also I thought I'd once read something about how a cable over a few feet had to have the same connector on both end by code.

 

[Grog12]

It sounds like OP is running Edison cords to use 120 volt power on his movers. 208 isn't a worry here.
.

Yeah Rochem and I arent suggesting 208v in sense of the OP lewdly as a similie.

 

[porkchop]

Also I thought I'd once read something about how a cable over a few feet had to have the same connector on both end by code.

I don't believe it's code, but it sure is much better when your adapters are small. I hate it when I run a 50 foot cable just to find out it's not what I wanted. One show I was on had some 100' female-to-female DMX cables that the head elec wouldn't let me change and they used to drive me nuts.

 

[FlashBang]

Thanks for all the great replies!

I'm have an L86 rack with EM264 modules. My dimmer circuits are all twist-lock connectors. I don't currently have spare twist-lock cables to slap an adapapter on. 208 V is indeed not an issue. And, finally, I don't have my cables laying up against the side of the fixtures - they are tied/taped to the batten, but still experience a good amount of heat when the surrounding fixtures are on.

Also a very good point was the DMX cable. It too is taped to the batten, but does come relatively close to the fresnel I have hanging next to the mover. How close is too close, in your opinion? What kind of measures can I take to protect my data cable?

I will at least purchase appropriate cable to withstand the heat - but the module-swap seems like the more logical approach (especially since some of my dimmers are shot anyway - I'm about to look into repair/replacing them). If I take this approach will I be able to share the power off that circuit between movers if they don't have power thru (ie. a powerbar type splitter)?

Thanks again!

 

[rochem]

Also a very good point was the DMX cable. It too is taped to the batten, but does come relatively close to the fresnel I have hanging next to the mover. How close is too close, in your opinion? What kind of measures can I take to protect my data cable?

I will at least purchase appropriate cable to withstand the heat - but the module-swap seems like the more logical approach (especially since some of my dimmers are shot anyway - I'm about to look into repair/replacing them). If I take this approach will I be able to share the power off that circuit between movers if they don't have power thru (ie. a powerbar type splitter)?

Assuming your fixtures are hung on a batten, and the cable is run along that batten, you will be fine. This is how most every theatre works, and it's not a problem. This is true for your power as well as data cable. Assuming you swap modules, you need to keep in mind that you will actually swap TWO dimmers for every one module you swap - so, if you want dimmer 37 to be a non-dim module, dimmer 38 will also be a non-dim module. This is important if you're short on raceway circuits, as you're losing two dimmers instead of just one. However, ML power can be two-fered just like dimmed power can - ideally, you would have every ML on its own circuit so that you could power cycle individual fixtures if required, but that's not crucial in this instance. If you end up going with running cable up to the pipe instead of swapping modules, you do need to go out and buy real 12/3 SOOW cable, instead of using your extension cords.

 

[FlashBang]

I'm not TOO stressed with my raceway circuits, but its always easier when you don't really have to worry about running out of circuits. What kind of system would a professional house put in place to provide non-dim power if they were unable to re-assign current rack modules? Would they install a new rack capable of both dim an non-dim? Would they have an electrician install electrical outlets somewhere on their grid?

If I continue to run extensions from the stage up, the only portion of cable which experiences high-temperature use is the portion along the batten.

Would it be practically safe to use regular duty cable for the portion of the run between the outlet on the stage and the end of the batten, and then heavy duty cable along the batten itself? Would a fire marshall or AHJ have a problem with me doing this?

Continued thanks..