Dedicated circuit installation (welder)

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  #1  
Old 09-19-02, 09:14 AM
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welderboy
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Dedicated circuit installation (welder)

I just purchased a new 220V welder and want to install a dedicated circuit to the garage to run it off of. The problem is there isn't any more room in my main panel. I'm thinking that I need a sub-panel but am unsure of how exactly to hook one up. Anyone know of a web page with a wiring diagram for this installation? Here's what I want to do:
1. Remove four single pole breakers form other parts of the house
2. Install two double pole breakers in place of the four singles, one for the welder and one for the sub-panel.
3. Rewire the four single pole breakers in the sub-panel.
Questions:
1. What size/type wire should I use from the welder breaker to receptacle (aprox 50 ft run). The welder has input amperage of 28A for 220V. The owner's manual recommends a 30A for circuit breaker, time delay? And 40A for normal operating?????(unsure of what this terminology means).
2. What size sub-panel and wiring should I use? I'll probably relocate four of the regular 15A household breakers to the sub-panel.
3. Do I mount the sub-panel right next to the existing breaker box?
4. Is there anything tricky about installing a sub-pannel?

Thanks in advance for any help.
 
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  #2  
Old 09-19-02, 11:59 AM
A
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Old 09-19-02, 12:39 PM
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Yes, aphares gave you a goodlink,, but run the welder off of the sub instead of runnig 2 circuits. 2 to a building isnt legal and no point anyway. Plus you save 2 more spaces in the panel.
http://www.homewiringandmore.com/hom...detgarage.html This is the page in the link that Aphares gave you.
 
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Old 09-19-02, 12:45 PM
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I read your q1uestion wrong anyway,,, but,, you might see if you can use a couple of tandem breakers to gain spaces. What feeds the garage now? You could use the spaces from that to put sub in garage which is waht you should have if you going to be doing much work there. That leaves power for aditional equipment. By the way,, this site has a welding forum also. http://forum.doityourself.com/forumd...s=&forumid=106
 
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Old 09-20-02, 08:15 AM
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Remove a 3-wire cable from the existing panel, a cable with the Red and Black wires connected to either 15 or 20 amp single-pole breakers, and then remove the breakers. Set a 70 amp 2-pole breaker in the 2 slots made "spare". You MUST have 220 volts across the terminals of the 70 amp breaker. Set a 12-circuit sub-panel next to the existing panel using a 1" steel conduit nipple 3"-4" long between the panels, trying to use the "knock-outs" in the sides of the panels. You can use 1-1/4" to 1" reducing washers if you "knock-out" an opening to large for the 1" nipple. You'll use two 1" lock-nuts and one 1" plastic bushing on each end to the 1" conduit nipple to secure the threaded ends of the nipple to the panel enclosure. Connect 2 Black #6 wires between the 70 amp breaker terminals and the "Main Lugs" of the sub-panel".Connect a #8 White wire between the Neutral terminal strips of both panels. Bolt a Grounding terminal strip to the metal of the enclosure of the sub-panel which you have exposed by removing the paint covering the metal where you locate the terminal strip.Connect a bare #8 wire between the Grounding terminal bar in the sub-panel and the Neutral terminal bar in the "Main" panel-you can remove the insulation from a section of the #8 White wire you purchased for the Neutral connection.Set a 40 amp 2-pole breaker in the sub-panel for the welder branch-circuit. You'll need two #8 wires between the 40 amp breaker and the welder receptacle and a #8 Equiptment Grounding Conductor between the Grounding terminal on the welder receptacle and the Grounding termianl bar in the sub-panel.-----Good Luck!!!
 
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Old 09-20-02, 08:37 AM
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Pat,,,, the welder circuit is going to another building,,, a detatched garage.
 
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Old 09-20-02, 11:30 AM
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welderboy
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Thanks for the good information; it should be enough to get me started. I didn't mention it, but it is an attached garage, so running the wire shouldn't be a problem.
 
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Old 09-20-02, 12:38 PM
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Yes,,, that is a different matter with an attatched structure. You could get by with a 10 wire at that distance and a 30 A breaker. 8 wire certainly wont hurt anything though if you are going to try to choke .035 thru that machine.,, if you do lots of body stuff drop down to .030 and it would certainly run it well and run good on a 10. But that 28A rating assumes the machimne is running wide open with the maximum size wire in it. (takes about 25 A to run .035 at 250 IPM,, if you slow this to 200 it would be ok) Depending on your main panel you could still get a couple of tandem breakers and avoid a sub if you wanted to,,, but the sub would give you way more room and you can hook the welder to that if you want.
 
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Old 09-20-02, 03:37 PM
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Pattbaa:

I believe you would have a code vialation to install #6s on a 70amp breaker.
 
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Old 09-20-02, 07:50 PM
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resqcapt19
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aphares,
There are special rules for conductor and OCPD sizing for electric welders. See 630.11 and .12. These rules permit larger than normal OCPDs just like motor circuits.
Don
 
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Old 09-20-02, 07:54 PM
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If so ok:

Ok, but that would apply to the branch circuit feeding the welder, not the panel feeders.
 
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Old 09-20-02, 08:02 PM
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resqcapt19
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Your correct, I didn't read all of the posts close enough. The only way to be code compliant with #6 on a 70 amp breaker would be if the equipment and terminals are listed for 75C use.
Don
 
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Old 09-20-02, 08:07 PM
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resqcapt19:

At 75'C #6 for the Sub feeders is still only good for 65amps, but since it is under 100amps we must use the 60'C rule.
 

Last edited by aphares; 09-21-02 at 08:01 AM.
  #14  
Old 09-20-02, 08:33 PM
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I know you are allowed larger ocpd's on welders. I would tend to think that it might be more common on industrial machines with heavier transformers. We have always used a 50 for a 50 recept and 30 for 30 on the small machines most homeowners would have and have never had a problem even running them wide open. Just a thought,,, to only upgrade the breaker if there was a problem,,, try the rated one first.
 
  #15  
Old 09-21-02, 12:57 AM
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resqcapt19
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aphares,
Look at 110.14(C)(1)(3). This rule only limits us to 60C wire sizes where the equipment is not rated for a higher temperature. We are under 800 amps and 240.4(B) permits rounding up to the next higher standard size of OCPD. 65 amps is not a standard size so if the equipment is rated for use with 75C conductors, you can put the #6 on a 70 amp OCPD.
Don
 
  #16  
Old 09-21-02, 08:08 AM
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Ampacity:

Feeders can go up, but branch circuits must go down.
Most generaly residential breakers have a Symmetrical amps at 10,000, and only rated for 60'C, As well as most residential devices.
 
  #17  
Old 09-21-02, 09:31 AM
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Branch circuits can go up too, as long as thre is only one outlet on the circuit.
 
  #18  
Old 09-21-02, 02:01 PM
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resqcapt19
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aphares,
First many breakers above 50 amps are listed for 75C terminations. Second we are talking about a feeder, but it doesn't make any difference. Third please cite the code rule that says 240.4(B) doesn't apply to branch circuits. The only branch circuit conductors that 240.4(B) doesn't apply to are conductors for multioutlet branch circuits supplying receptacles for cord-and-plug-connected portable loads.
Don
 
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