240v outlet wiring

[schmism]

As CJ said you can't run a 50 amp breaker and use smaller wire cause its a welder. You must size the wire for the circut.

Its also code that you size the receptacle at the end for the circuit. In theory its a nono to put those 35cent 15 amp receptacles on a 20amp circuit.

So if your welder has a stock 30amp plug on the end, you have to put a 30 amp receptacle in, and wire it for no less than 30 amp wire and match the breaker to the wire. I mention it this way because if the welder has the stock plug on it, the manufacture is bard from putting a 30 amp plug on a device that requires a 50 amp supply. So one of the easy things to do is to start with the (stock) plug.

Also note that NEC normally wants you to put one 220/240v receptacle per breaker. But they do allow a shop welder/shop "tool" to have more than one outlet wired on the same breaker. The idea being they understand you have one welder and only have it plugged into one of the 2 outlets at any given time.

 

[Groo]

Its also code that you size the receptacle at the end for the circuit. In theory its a nono to put those 35cent 15 amp receptacles on a 20amp circuit.

There should be no code problems as long as the breaker is the smallest element in the chain. correct?

I don't see a problem sticking a 50 amp plug on a 30 circuit. It will just pop if you try to use more than 30 amps.

For a welder, I'd feel safe with the absolute minimum wire for the circuit. For a more continuous draw load, I tend to upgrade beyond the bare minimum when its practical.

 

[murphy1244]

There should be no code problems as long as the breaker is the smallest element in the chain. correct?

I don't see a problem sticking a 50 amp plug on a 30 circuit. It will just pop if you try to use more than 30 amps.

For a welder, I'd feel safe with the absolute minimum wire for the circuit. For a more continuous draw load, I tend to upgrade beyond the bare minimum when its practical.

smart man..:thumbsup:

 

[grsthegreat]

There should be no code problems as long as the breaker is the smallest element in the chain. correct?

I don't see a problem sticking a 50 amp plug on a 30 circuit. It will just pop if you try to use more than 30 amps.

For a welder, I'd feel safe with the absolute minimum wire for the circuit. For a more continuous draw load, I tend to upgrade beyond the bare minimum when its practical.

you are correct.. nothing says you cant install a 50 amp plug on a #10 30 amp wire AS LONG AS YOU INSTALL A 30 AMP BREAKER. As stated previously you cannot use a 50 amp breaker on a #10 wire. But you know if you use a 50 amp outlet... somewhere down the line someone is going to try and run a 50 amp something or other on it... and hopefully they wont just upsize the breaker to a 50 and leave the #10 in the wall.

Personally.... i would run the #6 to the 30 amp breaker . so you can easily upgrade later on. 6/2 romex is about $1.60/foot. not too much overall. 10/2 romex is in the range of $0.40-0.50 or so.

 

[nickel plate]

aj2n,
Once you determine the proper sized components, go buy the wire, outlet and receptacle box and install that portion of the circuit yourself then call in an electrician to do the breakers and final wiring at both ends. Doing just that will save you some money.

 

[lostcause]

Depending on the connector you will have 3 pins or possibly 4 pins. Again your welder manual should have some info on this. There will be 2 hot wires 1 from each side of the dual breaker. There will a neutral wire that goes to a neutral bus bar. That will be the one with all of the white wires going to it. That will be all you need for a 3 pin connector. A 4 pin will have a ground wire that will go to the ground bus bar.

unless i'm mistaken, a 3 wire plug (240v) will have two hot wires and a ground (no neutral). a 4 wire plug (120v/240v) will have two hot wires, a neutral and a ground. even though they ultimately end up in the same place i don't think you are supposed to hook the ground on a 3 wire plug to the neutral bus.

As stated previously you cannot use a 50 amp breaker on a #10 wire. But you know if you use a 50 amp outlet... somewhere down the line someone is going to try and run a 50 amp something or other on it... and hopefully they wont just upsize the breaker to a 50 and leave the #10 in the wall.

i know you know more than me about the subject, and i know it gets hashed over all the time, and i'm not trying to cause trouble, but can you explain why nec article 630 is not valid? i hear all the people say that inspectors won't approve it and so on, but please explain why a rule remains written down but everyone says it is not valid. yes, i know there are labeling requirements for the duty cycle of the circuit and so on, but if it is done by the book how can it be disputed? to me it's like a police officer writing you a ticket for going 50mph in a 55mph zone because he personally feels that the limit should be 45mph.

 

[hr3]

Maybe this will help..
...its all about duty cycle. Arc welders are allowed to have their branch circuit conductors derated by a factor based on the duty cycle of the welder. So lets take your AC225 stick welder by lincoln electric. If the nameplate states the I-eff you are required to use it as your minimum circuit conductor ampacity. I've never seen it stated on a stick welder. If that isnt stated you use the rated primary input amps (not output) of the welder. You then take the mutipler factor in the table listed in NEC table 630.11(A) that corresponds to the duty cycle times the primary input current of your welder.

Example: Lincoln AC225 with an input rating of 50 amps to provide the maximum output currents.
The AC225 has a duty cycle of 20% (lincoln website spec for that welder) looking at table 630.11(A) the factor for non-motor welder is .45....

So .45 x 50 = 22.5 amps so this would require 30 amp 10 awg copper wire.... next size up from #12 awg copper which is 20 amp rated.

Now overcurrent protection can be as much as 200% over that rating, so the next overcurrent size up from 22.5 is 25 amp breaker. 200% of that is..........2 x 25 = 50 amps.

So you could breaker at a maximum of 50 amps and use 10 awg minimum for your conductors. You could also breaker at 30 or 40....up to 50.

So the circuit for your welder would be....

Minimum 10 awg copper rated 30 amps.
Maximum OCPD 50 amps.

The #8 awg is allowing for voltage drop.

Why the small wire..... because the welder has a 20% duty cycle. Which means you cannot weld longer than 2 minutes continuous out of a 10 minute time period. Therefore the wire will not get hot enough to damage the insulation. And most welders today have overload circuit protection that normally turns on a fan when they start getting too warm and will trip the internal overload device if they exceed the duty cycle by too much of a margin and shut the welder down.

 

[Inspector507]

i know you know more than me about the subject, and i know it gets hashed over all the time, and i'm not trying to cause trouble, but can you explain why nec article 630 is not valid?

Finally, someone who has read and understands Article 630 of the NEC.

 

[JoeL4330]

both my welders have an installation section in the manual...worth reading ...and, each calls for a disconnect, something I didn't see mentioned in the posts ...if you're thinking you can just switch the breaker on/off, then you might investigate an "SW"rated breaker.