Wiring for a Welder

Doug W · Oct 1, 2005

I am planning on running a 20ft line for my new to me Lincoln Squarewave 175. The Lincoln manual recommends a 100 amp breaker with #10 copper wire or 125 amp breaker with #8 copper wire. The latter is for AC Tig Welding at 150 amp and 25% duty cycle.

Usually a 50 amp circuit is #8 wire. What gives??

JL Sargent · Oct 1, 2005

Maybe one welder is more efficient than the other.

Doug W · Oct 1, 2005

Both are the same welder. The #10 wire is for AC/DC Stick or AC Tig up to 110 amp. The second is for AC Tig up to 150 amp.

Still baffled about the small wire size for a breaker of 100 or 125 amps??

johnoder · Oct 1, 2005

I ran #2 hot wires and #4 neutral about 40ft when I installed my Synchrowave 250 in 1990. This comes off a 100 amp breaker.

John

JL Sargent · Oct 2, 2005

I dont know why I thought it was two welders.

Anyway I bet you'd be fine with the 100/10 solution unless your gonna go with the max alot. I believe my Lincoln tig 250 is on a 100amp breaker. Seems it would be overkill for a 175 machine.

Dave A · Oct 2, 2005

Something is a bit strange, as you have noted. How many amps will the 175 pull at max rating? Size your wire for the ciruit you are going to plug it into for that amperage. Number eight is good for up to about forty amps over a short run and the machine should pull less than that?

Went to Lincoln's site and they now show a 185 TIG machine. Max amperage is 64 amps at 230 volts, single phase 60 cycle. Assume your machine pulls a bit less that that. Even at 55 amps, number eight is marginal, but how often would you pull max amps?

There is no way you would want to put a 100 amp breaker on a circuit with number eight wire. They must be talking about a subpanel size of 100 or 125 amps, which would have several individual circuits and breakers of appropriate sizes?

Doug W · Oct 2, 2005

OK

230V AC/DC stick & DC tig with 150amps ouput requires 53amps at 25% Duty Cycle, (the max)

230V AC tig with 150 amps output requires 65 amps at 25% Duty Cycle.

Here is the link to the Lincoln manual manual

The wiring info is on page 8.

still confused...Doug W

Dave A · Oct 2, 2005

I see what you mean when I read the Lincoln manual.

See this site for wire/amperage information.

http://www.bnoack.com/index.html?http&&&www.bnoack.com/data/wire-resistance.html

Frankly, from the research I have done on the net on this issue, there are a number of sites, charts and data. They do not all agree.

You can pull more amperage over a short run of wire than a long one. The manufacturers all recc that you do not use extension cords. Apparently there is more current loss, or resistance, as this site suggests.

From what I know of wire and breaker sizing, their reccs are for wire that is too small. Rather than a number eight, a number six would seem more in line with max amps, because it is not normally a continuous load and that is what will cause heat buildup in undersized wire.

However, I am not an electrician.

ExcessiveDilutivity · Oct 2, 2005

Article 630 in the NEC explains it.
630.11 says that since an arc welder has a definite duty cycle, you can multiply the input amperage by a factor to determine the minimum ampacity of the supply conductors. The idea is, you can pull more than the rated current through the wire for a short time, after which the welder will trip out on it's thermal overload, giving the wire time to cool off.

630.12 says that the overcurrent protection can be rated at no more than 200% of the rated input current on the welder and no more than 200% the conductor ampacity.

Nate

Doug W · Oct 2, 2005

Thanks Nathan!
I was guessing (being the key word)it had something to to with the 25% duty cycle, but wanted to ask first.

Since the welder only draws 65amps why the 125amp breaker? High amp draw at inital striking of the arc??

wippin' boy · Oct 2, 2005

drycreek is right ....
it doesn't mater what your running to what....
breaker is to be sized to wire not load...
#10 fuse at 30 amps max
#8 fuse at 55 amps max
(N.E.C.)
it goes up at about that scale with a 100 amp service requiring about #3....
my guess is a 55 amp service would hold this welder..."GUESS.... not having seen litureture"
the intial surge should not trip breaker

ExcessiveDilutivity · Oct 3, 2005

Heh, this happens every time I quote that article.

It's article 630, in the 2002 NEC it's pages 502 to 504 or pages 882 to 885 in the 2002 NEC handbook. Grab a code book and see for yourself. That said, I wire my welders as I would a regular branch circuit.

Furthermore, the correct wire for a 100 amp service would be #4 copper or # 2 aluminum, table 310.15(B)(6) allows that.

Why they allow upsizing the breaker, I'm not sure right now. I'm in the middle of a move and alot of my reference material is back at home.

Nate

snowman · Oct 3, 2005

#8 fuse at 55 amps max

And that is pushing it. I run #6 for anything that is labled 50 amps. I'd rather pay a couple bucks extra than have a fire. I dont put much trust in breakers poppign at the right time.

30 I will run at 10, 40 at 8 and 50 - 60 at 6, anything above, I haven't wired.

-Jacob

lalatheman · Oct 4, 2005

Doug,
I have a Lincoln Squarewave 175 too and thought Lincoln recommended a 50 amp breaker. I'll check the booklet tomorrow, though.

Dave

wippin' boy · Oct 4, 2005

#3 ..is .."about".. #4 ..didn't have my chart handy
.
and as sure as I 200%ed a welder service joe tomorrow looks at the fuse's and say's.. "this thing can hold a 50 horse compressor too, I'll just drop it out the bottom of the welder box"..
wasn't douting your quote just coverin' my butt for when they move the welder and there hangs my service with 100 amp overload protection on #10

Fountain Chuck · Oct 5, 2005

I also have the Lincoln 175, the local electric shop in town reccommended a 50 amp breaker. Been running that for 3 years now, no problems. I also have a 100' ext cord that I made with 8 ga wire, works like a charm, just my experiance.

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Wiring for a Welder

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