Yet another help with wiring up a welder

[buening]

I'm sure this has been tackled before but since 230v wiring is specific to the machine, I thought I'd post for help. I recently purchased a Lincoln Power Mig 255. Page 10 of 53 has the electrical info:

My house breaker panel is in the basement and the outlet I'm putting in the garage will be a straight shot to the breaker and the run will be between 10' and 15'. Per the owners manual, it says the input amperage for 230v is 46A. It also says I'll need a 60a breaker and can get away with #10 wire, which I assume is THHN and not Romex. Doesn't the wire size seem a little light and the breaker a little high? I was planning on getting some 6/2 romex, but even it is only good to 55A according to the ampacity charts I'm finding for NM-B wire. Could a 50A breaker be used?

This welder will be very sparsely used in my garage while restoring my mach and I'm doubtful it will ever see its upper limits. I basically bought too big of one just in case

So let me know what breaker and wire size is needed per the NEC.

 

[Aceman]

Welders let you get away with smaller wire than usual because of their duty cycles.

Since it's only 10-15' away, I'd personally run the 6-2 and not think twice about it. Use a 60 amp breaker and a 50A? recep to match the cord.

 

[Alchymist]

If you are ONLY going to use the welder on that circuit, #10 will work. If you Just MIGHT someday want to use it for something else - use the #6. And if you use the #10, the outlet is SUPPOSED to be marked "FOR WELDER USE ONLY".

 

[buening]

I have no other equipment that uses a NEMA 6-50 plug and my garage is small enough I don't have room for any kind of machine that uses 220v (air compressor is already hard wired to disconnect box and heater is already wired up), so yeah this would be a dedicated circuit for the welder. Thanks for the note on labeling the outlet!

I didn't think about the duty cycle allowing the smaller wire size. Thanks for the info guys.

 

[pattenp]

#6 NM (Romex) is 55A @ 60C and can only be sized by 60C but you can over current protect it at 60A. #6 THHN/THWN can be sized @75C which is 65A and can be over current protected at 70A. NEC allows you to use the next standard size breaker. I'd go ahead and use the #6 NM so you would have a circuit that could be used for other things.

 

[Aceman]

#6 NM (Romex) is 55A @ 60C and can only be sized by 60C but you can over current protect it at 60A. #6 THHN/THWN can be sized @75C which is 65A and can be over current protected at 70A. NEC allows you to use the next standard size breaker. I'd go ahead and use the #6 NM so you would have a circuit that could be used for other things.

Are you making a general statement about ampacities or stating the rules as they apply to welders?

I'd imagine most members on here don't realize there are different rules for welders, you can pretty much take the "general ampacity" rules for wire and throw it out the window when it applies to welders.

 

[sberry]

I like 8 and a 50A breaker. The 60 is fine for the 255 but you wont need it for home use with C25 gas and small wire, reason for a 50 is it makes it a common welder circuit, some of the smaller machines are designed to be run on circuits to 50A.

 

[pattenp]

Are you making a general statement about ampacities or stating the rules as they apply to welders?

I'd imagine most members on here don't realize there are different rules for welders, you can pretty much take the "general ampacity" rules for wire and throw it out the window when it applies to welders.

I'm stating the rules for sizing conductors if the circuit is for general purpose use, not as a dedicated welder use only circuit. That's why I said the circuit can be used for other things.

 

[Zeke]

How does one go about convincing an inspector that 10 ga wire protected with a 60A breaker is for "welder use only?" I'm serious, so don't get me wrong. Could you hard wire the welder to that circuit to make that meet code? Surely just a label isn't going to cut it.

 

[Alchymist]

How does one go about convincing an inspector that 10 ga wire protected with a 60A breaker is for "welder use only?" I'm serious, so don't get me wrong. Could you hard wire the welder to that circuit to make that meet code? Surely just a label isn't going to cut it.

I do believe that if the outlet is labeled as to welder use only, that's all that is required.
Could be wrong, I was once.

 

[pattenp]

I've looked through the NEC and I can't find any wording that labeling the outlet as welder use only is required. IMHO is just best to wire the circuit based on the plug size.

 

[Zeke]

Could be wrong, I was once.

You're way ahead of me!

This is the best place on the net to learn electrical. 'Nother 20 years of reading I might go into the business at age 87.

 

[Alchymist]

I've looked through the NEC and I can't find any wording that labeling the outlet as welder use only is required. IMHO is just best to wire the circuit based on the plug size.

Don't have the latest NEC handy, but sections 210-20 and 630 in the older books address welder circuit exceptions, and the only label requirements are for the welder itself and any cable trays carrying welder cables. Anyone have the latest NEC to check?

 

[buening]

This is the best place on the net to learn electrical. 'Nother 20 years of reading I might go into the business at age 87.

Couldn't agree more! If there's one thing I know I'll get an answer for, its in the electrical section.

 

[pattenp]

Don't have the latest NEC handy, but sections 210-20 and 630 in the older books address welder circuit exceptions, and the only label requirements are for the welder itself and any cable trays carrying welder cables. Anyone have the latest NEC to check?

I have the NEC 2011 and those are the sections I went through and some other sections trying to find it. There is a marking requirement for the welder itself but I don't see any requirements that the primary power outlet shall be marked as "welder use only". Unless I just missed it.