Where to find... 208V distro

G

GageStryker

Member
Hi, guys!

Just ran into a different kind of problem (as opposed to the ones from yesterday) - purchasing a 208V moving light distro. Would you believe I've always rented one until now?

I'm looking for something like this Spectrum - Products - Moving Lights Power Distribution Modules but don't need the DMX thru capability or the sokapax out (although I wouldn't mind it)... and the big change... I'm looking at getting a straight 208V distro (no 120 capability) that I could run with a 4 wire connection I'm not sure if that distro would operate without a neutral connection and if not if I'd need to get it CSA or UL listed again. I'd much rather go with an out of the box solution.
 
GageStryker said:
I'm looking at getting a straight 208V distro (no 120 capability) that I could run with a 4 wire connection I'm not sure if that distro would operate without a neutral connection and if not if I'd need to get it CSA or UL listed again. I'd much rather go with an out of the box solution.
Click to expand...

You would need the neutral because the phases still wouldn't necessarily be perfectly balanced. If you have 7 lights (we'll say same unit drawing the same power for simplicity), then you might have 3 on phases AB, 2 on phases BC, and 2 on phases AC which would not be perfectly balanced and would certainly require a neutral (or you could wind up with 230V on one pair and 170V on another... not calculated, just making a point).
 
Leprecon makes some awesome (well priced) little 208 distros. I would check them out.
 
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photoatdv said:
You would need the neutral because the phases still wouldn't necessarily be perfectly balanced. If you have 7 lights (we'll say same unit drawing the same power for simplicity), then you might have 3 on phases AB, 2 on phases BC, and 2 on phases AC which would not be perfectly balanced and would certainly require a neutral (or you could wind up with 230V on one pair and 170V on another... not calculated, just making a point).
Click to expand...

In this configuration, the neutral would still not be connected to anything.

EDIT: To clarify, even though the source is Wye, the loading is Delta, and will maintain the 208 voltage range. (less any cable drop.)
 
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photoatdv said:
You would need the neutral because the phases still wouldn't necessarily be perfectly balanced. If you have 7 lights (we'll say same unit drawing the same power for simplicity), then you might have 3 on phases AB, 2 on phases BC, and 2 on phases AC which would not be perfectly balanced and would certainly require a neutral (or you could wind up with 230V on one pair and 170V on another... not calculated, just making a point).
Click to expand...
Um, no. Imbalance of phases has no effect on voltage. When powering only 208V moving lights, there is no connection to the neutral. Since it doesn't run from the distro to the lights, it doesn't have to be run from the disconnect to the distro. On a 208V ML PD, the neutral is used for the convenience outlets and the meters, if present.

But GageStryker, why would you not run a neutral? Does it not exist in the panel? See the thread http://www.controlbooth.com/forums/...ird-electrical-service-what-am-i-working.html .

For your distro, how many 208V circuits? What kind of output connector? What kind of input connector?
Would this work for you?
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PowerHOUSE™ Portable Distribution Boxes: Moving Light Pagoda Combination | Lex Products
 
Thanks so much for all the discussion, guys - and I'm glad that "you need a neutral" got discussed.

As to the "why would you run without?" question, the "weird electrical service" is definitely present.

I'll make a note that yesterday I had a liscenced electrician walk physically walk through this with me, to make sure that I wasn't overlooking anything silly. So come with me on a walk through electrical shenanigans.

So here's how it is. I have three 30A 3 phase receptacles onstage - run 3 phase direct from a CDP, but they're 3 wire, not 4 wire (for those uneducated, when you're talking electrical runs in a panel, you don't count the ground, even though it's there). However, there's a neutral dangling in the box, so all they need is a new receptacle and... voila! 120/208V power.

However, I also have a similar service run up to my catwalk, a place I'd really love to have 208V power. And by similar I mean looks similar, when opened up reveals a "WTF?" situation. There's a receptacle marked as 20A 3 phase, 208V. Open it up and both the find the wire's OK to upgrade to a 30A service, and there's enough service to the panel that replacing the breaker isn't a problem. This one is run as a 3 wire service as well - but there's no neutral in the panel. My electrician friend helped me diagnose the problem - they'd run a three phase service over wires marked as two hots and a neutral, and marked it in the panel (legit to code, but not best practices).

When I explained that I was running 208V devices only, but wanted the ability to move a distro upstairs or downstairs as required, he told me they could put in a 5-conductor receptacle, not service the neutral, and mark the receptacle as 208V only. The only downside being that 120V won't work upstairs. Since I already have a ton of 120 on the catwalk, that shouldn't be a problem. So my convenience outlets on my distro (if I get one with any) won't work upstairs.

So ends today's ballad of "the drawings don't match the breaker panel layouts don't match the receptacle don't match the service don't match the sharpie lettering on the box but in the end, it is all legit."
 
Labels fall off. The better thing would be to install a NEMA 15-30R on that box. That is designated as 250 volt 3 phase with ground. (4 blades total) It is incompatible with any of the 4 blade 120/240 plugs and would be an alert 10 years from now that there was no neutral at that location.
 
JD said:
Labels fall off. The better thing would be to install a NEMA 15-30R on that box. That is designated as 250 volt 3 phase with ground. (4 blades total) It is incompatible with any of the 4 blade 120/240 plugs and would be an alert 10 years from now that there was no neutral at that location.
Click to expand...

This is definitely the best way to do things - do not, under any circumstances, wire a 5-wire plug without the ground. That's just asking for fried gear and/or humans.
 
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