Range Style Plug...

JCarroll

Active Member
Im doing a gig at an older theatre and it has these two Range style looking plugs on either side of the stage. Metering between hots is 208 and hot to neutral is 118... so its three phase. As far as I can tell it only has 3 slots and no ground at all unless it is a screw tap type thing near where it goes into the floor. Can anyone tell what plug I'm talking about and how many amps it can handle? I'm pretty sure it will be 50A per phase but if anyone knows otherwise...
 
So like this?
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http://jcwinnie.biz/wordpress/?p=933
Except 208V line to line, and 118V line to neutral?

Lacking an EGC, the receptacle should not be used to power stage equipment.

As for "how many amps it can handle," that's determined by the receptacle's rating OR the OPD supplying it, whichever is smaller.
 
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There are MANY types of plugs like that, we would need a picture to give you a definitive answer. However that said 99% of the people on here including me are going to tell you right here and now that the plug you mention IS NOT suitable for use in theatrical environments as it has no ground.
 
Yes that is the exact plug. The ground is confirmed on the pipe that leads down under the stage... it has a screw clamp style attachment and shows continuity to other grounded outlets.

that doesnt matter. The receptacle doesnt have a ground pin. Also, its not three phase, its a single phase receptacle that happens to be supplied from two phases of a three phase source.

The only safe way to utilize it would be to have a licensed electrician do whatever is necessary to replace it with a proper receptacle (nema 14-50). Might be as simple as swapping out the receptacle, might require pulling in a EGC or a neutral -who knows how that existing receptacle is wired..
 
Sure have seen a lot of those puppies over the years. Any of us here could be liable if we said it was ok. As they cut corners on that, you might also see what gauge wire is used and what size breaker it is on. (Recently ran into one, wired with 10/3 and on a 100 amp breaker!)

More likely to find that kind of setup in a club than a theater, but I guess idiots have cars and can move from building to building.

Nema 14-50 (modern range plug) would be a move in the right direction, but I actually don't -think- they are allowed in theater.
 
Nope!
Thus the "-think-" as I have been scolded for their use by others that indicate it is use specific. Possibly you could ask Steve.
 
Nope!
Thus the "-think-" as I have been scolded for their use by others that indicate it is use specific. Possibly you could ask Steve.

there is really no reason it would be disallowed. I cant find any prohibition of any particular receptacles..
 
The use of 3-wire range and dryer receptacles has caused a lot of confusion and misapplication over the years. During World War 2 the War Materials Boards decided to allow TN-C ( Terra Neutral Common ) grounding of cooking and clothes drying equipment in wood frame dwellings. TN-C grounding uses the neutral as the equipment ground as opposed to TN-S ( Terra Neutral Separate ) for branch circuits and feeders which uses separate neutral and equipment grounds.

Most electrical services in the U.S. are grounded TN-C-S with the neutral as the equipment ground as one and the same ahead of the service switch and separate equipment grounds downstream of the service switch. That TN-C was allowed downstream of a service during and after World War 2 has caused a lot of confusion.

A 4-wire range or dryer receptacle is legal on a stage provided that the plugs are field wired with extra hard usage ( no Js ) industrial cord.

It could be worse. There is a colorblind electrician running around Cleveland, Ohio. What he did at International Exposition Center was to get hot and equipment ground swapped on some 480 volt extension cords.

Mike Cole
 
Obviously, they put it there so you could have a working practical stove on stage if the show calls for it. Or if you need to make some food backstage, all you have to do is load in your own stove
 

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