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05-18-2009, 06:49 PM   #1
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## What size breaker

someone just gave me an old welder a craftsman dual range 295 amp welder.... i only plan to use 3/32nd rods around 110 range...... I have a detached barn with a sub ran from house using a 40 amp breaker with 6 GA wire not sure why... All that the barn really uses is 4 lights, one sensor light on the outside, and a few receptacles fed by 2...20 amp breakers....... what size breaker would you recommend for this welder? what is safe. what is the max breaker size i can add ..... I do not know enough to and cannot google the answer...do i need to replace the 40 in the house?

Last edited by Ineedhelp2009; 05-18-2009 at 07:12 PM.

05-18-2009, 07:37 PM   #2
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Usually welders like this are on a 50 amp circuit. The trip curve of a typical 50 amp breaker pretty closely matches the duty cycle of the welder.

I've seen plenty of them on 30s though. That's what a typical temporary power box on a construction job will have. A 30 will trip if you weld for a long time at a high current setting, or if you stick the rod for more than about 5 seconds.

Here's what the code has to say; (Article 630).

1) Wire size; for a welder like you have, the minimum wire size is the rated input current multiplied by the value given in the duty cycle table. (20%=.45, 30%=.55, 40&=.63, 50%=.71, 60%=.78.) Most buzz-boxes are 50 amps and a 20% duty cycle.

2) Breaker size. There's no minimum, but the maximum cannot be more than 200% of the rated current. If there's a cord and plug, the breaker size cannot be more than the rating of the receptacle. The breaker cannot exceed 200% of the wire size in any case.

This is one of the few times you can have a larger breaker than normally allowed, but only if the welder is hard-wired.

Rob

P.S. If I were you, I'd put it on a 30. That way, if it does trip, there's a good chance that the main at the house will stay on, and thus the lights will also stay on.

Last edited by micromind; 05-18-2009 at 07:40 PM.

05-18-2009, 07:52 PM   #3
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Quote:
 Originally Posted by micromind Usually welders like this are on a 50 amp circuit. The trip curve of a typical 50 amp breaker pretty closely matches the duty cycle of the welder. I've seen plenty of them on 30s though. That's what a typical temporary power box on a construction job will have. A 30 will trip if you weld for a long time at a high current setting, or if you stick the rod for more than about 5 seconds. Here's what the code has to say; (Article 630). 1) Wire size; for a welder like you have, the minimum wire size is the rated input current multiplied by the value given in the duty cycle table. (20%=.45, 30%=.55, 40&=.63, 50%=.71, 60%=.78.) Most buzz-boxes are 50 amps and a 20% duty cycle. 2) Breaker size. There's no minimum, but the maximum cannot be more than 200% of the rated current. If there's a cord and plug, the breaker size cannot be more than the rating of the receptacle. The breaker cannot exceed 200% of the wire size in any case. This is one of the few times you can have a larger breaker than normally allowed, but only if the welder is hard-wired. Rob P.S. If I were you, I'd put it on a 30. That way, if it does trip, there's a good chance that the main at the house will stay on, and thus the lights will also stay on.

Great thanks, THere is some 10-2 already ran to an outlet will just changed boxes and run a 30 amp breaker...

 05-19-2009, 08:53 AM #4 Member   Join Date: Jul 2008 Location: Pennsylvania, USA Posts: 272 Rewards Points: 250 Let's have the model number and we'll check for the manual. Lots of good info in there if we can get it...including OEM recommended power setup. __________________ Willis
05-19-2009, 06:43 PM   #5
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Quote:
 Originally Posted by williswires Let's have the model number and we'll check for the manual. Lots of good info in there if we can get it...including OEM recommended power setup.
113-201392
THanks

05-19-2009, 06:47 PM   #6
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Quote:
 Originally Posted by Ineedhelp2009 113-201392 THanks
Resolved thanks for your help. I put a 60 amp breaker in the house and put a 40 in the barn. The wire already ran for the outlet was 10 ground and 8guage hots...... Welder works will see it it trips.

Last edited by Ineedhelp2009; 05-19-2009 at 08:04 PM.

 05-20-2009, 10:45 AM #7 Member   Join Date: Jul 2008 Location: Pennsylvania, USA Posts: 272 Rewards Points: 250 Here is the manual for your welder, printed in 1980, in case you don't have it: Click on 'VIEW MANUAL" in the lower half of the page. http://www.managemyhome.com/mmh/owne...1392+CRAFTSMAN __________________ Willis Last edited by williswires; 05-20-2009 at 10:50 AM.
05-20-2009, 06:44 PM   #8
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Quote:
 Originally Posted by williswires Here is the manual for your welder, printed in 1980, in case you don't have it: Click on 'VIEW MANUAL" in the lower half of the page. http://www.managemyhome.com/mmh/owne...1392+CRAFTSMAN

alot of help thank you

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