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#96334 - 11/19/05 10:44 AM Welding circuit  
aldav53  Offline
Member
Joined: Aug 2001
Posts: 545
Chandler, AZ USA
I installed a welding circuit with a 60a breaker in the lower part of a split buss residential panel and put a 70a breaker (max size according to the panel specs) feeding the lower part of a the split buss.
The the welder draws 92 amps max. I didn't want to go over the 70a split buss feeder breaker, so I told the customer he probably couldn't run his welder at maximum without possibly tripping the breaker. Everything is installed up to code, but is this a good idea even being legal?

(This is the same panel I mentioned in the General discussion area about the ("no main disconnect".)


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#96335 - 11/19/05 11:40 AM Re: Welding circuit  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
A lot depends on the duty cycle of the welder. You need to or at least should look at Article 630 which specifically addresses welders.

Welder outlets, the conductors that feed them and the overcurrent protection for them do not follow the 'normal' rules.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#96336 - 11/19/05 03:16 PM Re: Welding circuit  
aldav53  Offline
Member
Joined: Aug 2001
Posts: 545
Chandler, AZ USA
I'll check that.
Its a Miller Tig welder


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#96337 - 11/19/05 09:29 PM Re: Welding circuit  
Tesla  Offline
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Joined: Jun 2004
Posts: 1,273
Sacramento, CA
93Amps would be extremely heavy current for a MIG welder used at a residence. That is most likely an instantaneous value.

If it is a Miller MIG running at 120Volts then 60A is way overkill. Just what kind of plug does it ship with?

Dig into their spec sheet; visit their web page.


Tesla

#96338 - 11/19/05 09:48 PM Re: Welding circuit  
renosteinke  Offline
Cat Servant
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Joined: Jan 2005
Posts: 5,316
Blue Collar Country
Welders get their own section in the NEC. It's worth looking up.

The nameplate will list a "duty cycle." This bit of info in turd is used to select your breaker and wire size. In theory, one could run #12, on a 100 amp breaker, if the duty cycle was low enough.
DOing so would probably be foolish, though. Replace the welder with another machine, and you're likely to have to re-do the entire circuit.


#96339 - 11/20/05 11:45 AM Re: Welding circuit  
HLCbuild  Offline
Member
Joined: Dec 2004
Posts: 209
Herndon,Va USA
Have you considered putting the welder breaker in the upper portion of the split buss panel and moving some smaller load down like maybe the water heater or dryer(double 30)to the lower portion?


#96340 - 11/21/05 12:24 AM Re: Welding circuit  
aldav53  Offline
Member
Joined: Aug 2001
Posts: 545
Chandler, AZ USA
Thats a great idea. Sometimes the obvious just flys right by ya. I check the loads on top.
Thanks,


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