Clothes Dryer Circuit

[kwired]

From the git-go on this thread, my position has been that the potential is there for both devices to be active at the same time.

eg. Dryer in a laundry room out of sight from welder. Dryer active, and user decides to weld the world's greatest steel statue.

What 210.23 says (by way of the NEC interpretation) is that the governing rule is that you cannot have multiple devices on the circuit that would demand more amperage than the circuit is allowed.

If I have a dryer that is 22 amps and a welder that is 19 amps, that would be allowed by 210.23(B), but prohibited by 210.23 because the demand load (41 amps) exceeds the 30 amp limit of the circuit.

Why would this be any different than if the same HO has a 20 amp 120 volt circuit in his garage or workshop. In that area he has a 12 amp table saw, a 13 amp air compressor, and uses all sorts of other electric tools, plus his lighting in the area is connected to the same circuit, maybe he has a refrigerator or freezer in there also.

This is a code compliant installation. Most of the time everything works fine. Once in a while he may be using the table saw and the air compressor kicks on. That alone may run that way for a little while but maybe the refrigerator is also running as well as the lights and possibly other small loads. He is likely going to trip the breaker.

If he doesn't want to have to have this happen his choices are:

learn to manage the loads so there is not too much running at one time

have more circuits installed to serve the area

not right but all too often done - replace breaker with higher setting

also not a great solution but often done - run an extension cord from a receptacle located elsewhere that is on a different circuit.

 

[renosteinke]

"and a welder that is 19 amps ...."

That's the problem. You can't simply take the nameplate amps in sizing a welding circuit. A welder is not like any other appliance. That's why you need to consider the duty cycle; that's at the core of how the circuits are sized so differently.

Because of this detail, one cannot give a general answer; the answer will change for each welder.

I will admit that there is an unenforceable element to the question: nearly every welder is 'portable,' and thus can be plugged in anywhere. In practice, though, most welders are quite stationary, living out their lives within a cord-length of the same power point. As such, I maintain that the difference in the circuit sizing methods demand a separate circuit for the welder.