Electrical question?

[SecondMonkey]

I'm wiring my shop with some heavy duty 30A twist lock outlets. I would like several outlets around the room, for convenience, but probably won't ever use more than one at once.

Does a 30A outlet like this need to be on a dedicated circuit, or can I use multiple 30A outlets on one 30A breaker....the same way you would with normal 15/20A household receptacles?

 

[94MaxGXE]

Yes.

 

[XS650]

Local and state codes can modify the requirements, but generally as long as you don't have automatic loads like air compressors or loads that require separate circuits by code, you can hang a lot of outlets on one circuit.

Try asking you local building inspection department as a hypothetical question, although that's a lot like asking a Jiffy Lube monkey what oil to use.

 

[SecondMonkey]

Originally Posted By: XS650
Try asking you local building inspection department as a hypothetical question, although that's a lot like asking a Jiffy Lube monkey what oil to use.

Yeah, that's the problem. I'm wondering more what the NEC has to say about this sort of thing? I know "normally" high amperage outlets are dedicated, but not sure if they "must" be...

 

[SecondMonkey]

Originally Posted By: 94MaxGXE
Yes.

I was getting a battery for my Jeep and the clerk looking in the computer asked "is that a four or a six cylinder?". I said "yes".

Everyone laughed at me because I thought she said "is that FOR a six cylinder?"...

 

[brianl703]

You cannot put multiple 30A receptacles on one 30A breaker. The only type of receptacles you are allowed to parallel are the standard 15/20A 120V type.

There was some discussion of this on electrical-contractor.net a while back.

 

[labman]

Maybe dig into the code yourself.

 

[severach]

NEC Article 630 for Welders makes several mentions of "Conductors that supply one or more welders" and so far as I can tell multiple outlets of the same ampacity on a single line of that ampacity is within the rules and will be safe so long as it is breakered correctly. I recommend reading Article 630 before constructing to ensure that you don't do anything outside the rules. You also may save money by taking advantage of the reduced conductor size allowances.

Doubling the conductors in those boxes is only going to make them harder to work with.

 

[labman]

Gee, I wish I could remember more about how the welding plugs were wired up in the factory I used to manage. There was an overhead platform with the 4160 to 480 transformer and a huge bank of motor starters. Most of the circuits were only hot when the motor starter was activated.

I do know we had welder plugs stuck here and there all over. I will bet them and the single leg feed to the lights and single phase were all on one circuit. The one engineer was very picky about sticking to code. Of course, that was 25 years ago.

 

[SecondMonkey]

Originally Posted By: severach
You also may save money by taking advantage of the reduced conductor size allowances.

Doubling the conductors in those boxes is only going to make them harder to work with.

Yeah, and all that extra copper $$$$! The biggest issue is that I want six outlets on two 30A breakers...I don't have room for six more double pole breakers!

I can totally see the NEC banning this sort of thing...but I can't think of a good reason why...as long as they're all on a correctly sized breaker. They're such a buzzkill.

 

[brianl703]

Originally Posted By: SecondMonkey

I can totally see the NEC banning this sort of thing...but I can't think of a good reason why...as long as they're all on a correctly sized breaker. They're such a buzzkill.


One possibility is that anything that requires a 30A circuit will say in the installation instructions that it requires a dedicated circuit.

Is it a dedicated circuit if it's got 2 other receptacles on it? Sure, you might not have anything plugged into those 2 other receptacles, but that is not a dedicated circuit because the possibility exists for additional loads to be plugged into it.

 

[brianl703]

Originally Posted By: SecondMonkey

Yeah, and all that extra copper $$$$! The biggest issue is that I want six outlets on two 30A breakers...I don't have room for six more double pole breakers!


You could install a subpanel. A 12 space main lug panel isn't very expensive.

 

[severach]

Originally Posted By: SecondMonkey
I can totally see the NEC banning this sort of thing...but I can't think of a good reason why...as long as they're all on a correctly sized breaker. They're such a buzzkill.

Read NEC Article 630. Not only is it not banned, they tell you what the limits are.