multiple 250V 50A Recepticles

[dmpaul]

I have multiple recepticles inside a mechanic service garage. The owner has a few pieces of equipment that he can plug in to these outlets. All of the equipment are of the same ratings. Right now I have 3 plugs thoughout the shop. One at each bay, he can plug in: High pressure sprayer, wire feed welder, arc welder, plasma cutter, On the normal activity, never will 2 or 3 for that matter will ever be used at the same time. Right now I have them all on the same 50A, 2-pole breaker. All are 3 wire cord, plug connected, from the factory, straight blades. Is this a wrong installation according to the code, but actually the breaker rating is right according to the load being used. He wants to add one more location, which will be a total of 4 locations then, now that seems a little strange but convience is everything. Should I change all recepticles to individual breakers, but remember that I already have a 42 space panel used up, could possibly make room for 2 maybe 4 poles. It is a brand new building less than 2 years old, 200A service. Mechanics garage really doesn't use much power, most everything is air powered, except convience plugs, lights, and welders. Right now all locations have #8 THHN conductors, all with separate raceways, and spliced with approved method in gutter under service panel. Must the conductor size be that of T.630.11(a), 100% of first 2 and 85% for 3rd etc....? I would appreciate any info reguarding any of this!
Thanks-

 

[tvgaconsultants]

Re: multiple 250V 50A Recepticles

I do not see why you could not install an other receptacle in this location. The protective device will function if the operator overload the circuit. This would be the only reason I would split up this circuit, if they continue to trip the protective device. Like you said it is being put in for convenience and not dedicated receptacled equipment. Think of is like duplex receptacles.

 

[roger deas]

Re: multiple 250V 50A Recepticles

Read 210.21(B)(2)

"Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle shall not supply a total cord-and-plug-connected load in excess of the maximum specified in Table 210.21(B)(2)"

Roger

 

[physis]

Re: multiple 250V 50A Recepticles

Can't 210.24 and table 210.24 be used.

 

[roger deas]

Re: multiple 250V 50A Recepticles

Physis, note that 210.24 sends you too 210.21 for specific requirements.

Hang in there, your getting the upper hand on the NEC.

Roger

 

[physis]

Re: multiple 250V 50A Recepticles

Upper hand, Roger?, I don't think so. Progress maybe.

OK I'm looking at 210.21(B)(2) only going up to 30 amps. But that might not be good enough for welders.

I see what your saying about 210.24, but it allows you to use table 210.21(B)(3) going up to 50 amps and this is still OK for multiple receptacles under 210.24, no? Or am I still missing something.

Thanks for the encouragement.

 

[james wuebker]

Re: multiple 250V 50A Recepticles

I believe that it's ok to add another one. One think you might want to remember that the items that your plugging into the circuit. Not sure want the standard type plug should be on the lets say the pressure washer. If it came with a 20 amp 240v plug on it and you have a 50 amp plug on it there could be a fire hazard there. If you have an overload on that washer you could burn up the washer and the washer's wire before the circuit trips. What I'm getting at is to make sure you have the circuit fuse correct for want you are using it for. You wouldn't put a 10 amp fan on a 50 amp circuit.
Bye now
Jim

 

[hurk27]

Re: multiple 250V 50A Recepticles

Jim if the pressure washer has an over-load on the motor (and they usely do) the OCP at the panel is only for fault current and can be larger than the rating of the wire. this is also true for the welders as it is allowed to go as far as 200% over the rating of the wire feeding the welder when the welder has overload pertection.

[ May 10, 2003, 06:03 PM: Message edited by: hurk27 ]

 

[james wuebker]

Re: multiple 250V 50A Recepticles

Hurk27, You are correct in what you say. I would believe in his shop the High pressure washer has a heater in it also. They will most of the time run on a 20 amp 240v circuit. The welders I don't have any problems with them. Remember have I agreed with adding another plug on this circuit. I just whated him to make sure that everything that he uses on the circuit will be safe on his 50 amp breaker. It doesn't hurt checking it all out, does it?
Bye now,
Jim