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-   -   copper verses aluminum for 50 amp circuit (http://www.diychatroom.com/f18/copper-verses-aluminum-50-amp-circuit-2272/)

wiggs 04-13-2006 01:56 PM

copper verses aluminum for 50 amp circuit
 
I would like to have a 50 amp outlet for an arc welder.I am currently wiring a garage with living space above.I have already pulled a #6-3 wire for the oven and I used aluminum,using advice from others,it's cheaper.Is it ok to use aluminum for the welder or should I use copper?My thought,not being a professional,is that the welder would draw more amps for a more extended period of time than a stove and possibly damage the aluminum.What are the pros and cons with copper verses aluminum besides the price?

crecore 04-13-2006 02:50 PM

I'm no electrician, but I am an engineer. Resisitivity at room temp of alum. is 58% higher than copper. This means voltage drop and ampacity drop due to heat. I think the duty cycle might have an affect. And certainly the length of run. My gut feeling is that it would be ok, but...

I would contact the welder manu.

good luck

jwhite 04-13-2006 04:32 PM

I am a professional electrician and beyond the service drop I would not install aluminum wire at all.

The pro is that it is cheeper, the con is you could burn your house down. It as to do with how much the wire changes in size with changes in temperature. even the changes made from use. It also has to do with the type of connector that binds the wires at the ends.

I would wire the welder in copper and re-wire the oven as well.

Speedy Petey 04-13-2006 04:56 PM

Quote:

Originally Posted by jwhite
..., the con is you could burn your house down.

I don't want to start a flame war, but as a broad statement this is a load of...you know what.
YES, smaller AL wire #10,12,14) is very suspect and is illegal. Larger (#6 and up) is perfectly fine to use for larger circuits and feeders. In fact, I cannot even get SER or SEU cable in cu in my area. Same with URD.
Treated correctly larger AL is as safe as copper.

jwhite 04-13-2006 05:15 PM

ser and seu are for panels.. al is fine.

The op is doing internal wireing.. I am sure he and you can find #6-3 w/g NM wire.

Speedy Petey 04-13-2006 05:49 PM

A welder, especially in a home, has FAR less duty cycle than an oven/range.
A welder would be fine using either.

wiggs 04-13-2006 11:16 PM

I have found out another factor may be involved.The oven/range is only 20 ft. away from the panel,where as the welder is 60ft.away from the panel.Other sources have told me if it is more than 75ft I should upgrade the wiring by one size.Also it could be mandatory after 100ft.Does the NEC state any standards for the footage away from the panel?

jwhite 04-15-2006 05:25 AM

Quote:

Originally Posted by wiggs
I have found out another factor may be involved.The oven/range is only 20 ft. away from the panel,where as the welder is 60ft.away from the panel.Other sources have told me if it is more than 75ft I should upgrade the wiring by one size.Also it could be mandatory after 100ft.Does the NEC state any standards for the footage away from the panel?

Per the NEC voltage drop is not required. It is a very good idea. Footage alone is not enough to figure it out. Here is a link to a site online where you can plug in numbers and figure the voltage drop. You should keep it to less than 5 percent total from the utility service drop. 3 per cent is great for any one circuit. http://www.csgnetwork.com/voltagedropcalc.html

Since the total circuit length is measured two the outlet and back. 1/2 the circuit length is length of cable one way from the panel to the outlet.


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