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#63690 - 03/24/06 12:46 AM 2- 30amp receps  
drgnz23  Offline
Joined: Feb 2002
Posts: 56
los angeles
i was just reading another topic from another forum about having 2 30a 220v receptacles on one circuit (welder and compressor) on one 30 amp breaker.(not being used at the same time0).Is this a safe practice? To my knowledge this shouldnt be done regardless if you dont operate at the same time....what do you think?

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#63691 - 03/24/06 02:08 AM Re: 2- 30amp receps  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,124
Why not?
I don't know of anything that says you can't have 2 receptacle outlets on a 30a circuit.

Greg Fretwell

#63692 - 03/24/06 04:12 AM Re: 2- 30amp receps  
e57  Offline
Joined: May 2003
Posts: 2,876
Depends on the load.... 210.21+210.23

And no, over-all I don't think it a safe or wise practice. There is no guarantee of only one in use at a time. One device cycles automaticaly, the other is a welder. [Linked Image] See 630... Although a welder is intermitant, and it is allowed to have multiple welders on the same circuit the OCP and wire size rules are expanded, and differ slightly from a normal branch circuit.

Without knowing the data plates and circuit particulars, I would say, no.

Mark Heller
"Well - I oughta....." -Jackie Gleason

#63693 - 03/24/06 04:28 AM Re: 2- 30amp receps  
macmikeman  Offline
Joined: Jul 2002
Posts: 717
Honolulu, Hawaii
Double pole - double throw switch?

#63694 - 03/24/06 05:35 AM Re: 2- 30amp receps  
iwire  Offline
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
All of us install multiple receptacle outlets on 15 and 20 amp circuits all the time with no idea at all what will be plugged into them.

Why would this practice suddenly become unsafe once we move to 30 amp circuits?

Article 630 gives us some options for saving money when supplying welders but we do not have to use those options, we can supply a welder with a 30 amp cord cap with a 'standard' 30 amp branch circuit.

I see no NEC reason not to do this, it in my opinion is a design choice.

If the person paying the bill tells me they are fine with one circuit I would have no problem supplying them with one circuit once I explained the circuit may trip if both units operate at the same time.


Bob Badger
Construction & Maintenance Electrician

#63695 - 03/24/06 08:28 AM Re: 2- 30amp receps  
PCBelarge  Offline
Joined: Jun 2003
Posts: 681
Dobbs Ferry, NY, USA
I agree with Bob.
If both units are used at the same time... the circuit breaker will open...exactly what the NEC wants to happen... but the customer, if not warned will not be too happy.

Pierre Belarge

#63696 - 03/24/06 11:26 AM Re: 2- 30amp receps  
renosteinke  Offline
Cat Servant
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
Assuming the nameplates require similar circuits, I see no problem.

BUT- that's a big assumption. The two appliances are treated quite differently as to wire sizing and over-current protection; Just because they have the same plug is no guarantee. Nevertheless, in Harry Homowners' garage, where Harry is going to putz around solo, it ought to work out OK.
Change that to a guy trying to run a business in his garage....and my answer will change.

#63697 - 03/24/06 01:38 PM Re: 2- 30amp receps  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,124
I am fixin' to do exactly the same thing with my welder and a new pressure cleaner I just ordered. In a practical sense I know I could unplug one and plug in the other but I am going to install another receptacle.

Greg Fretwell

#63698 - 03/24/06 02:50 PM Re: 2- 30amp receps  
ghost307  Offline
Joined: May 2005
Posts: 916
Chicago Illinois USA
I did the same thing at a big honkin' laboratory complex a few years ago. Each lab had a piece of equipment that the staff would roll to different places in the lab based on their particular research project. There were 3 possible locations, but each lab only had 1 machine...1 circuit, 3 receptacles.
Worked great.
No problems...Code or otherwise.


#63699 - 03/24/06 03:51 PM Re: 2- 30amp receps  
Texas_Ranger  Offline
Joined: Dec 2001
Posts: 2,402
Vienna, Austria
Please tell an innocent European why two appliances with the same voltage and amp draw would need different wire? I assume with some loads you could downsize some for cycling, but generally 30 amps are 30 amps, right?
Trip characteristics are a different piece of cake of course.

I think mainly it's a design thing - we usually put our CEE receptacles on dedicated circuits, so they can be loaded to their full ampacity.

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