Temporary 220V patch at Breaker Panel


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Old 03-12-07, 11:48 AM
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Temporary 220V patch at Breaker Panel

I have a temporary project where I need 220V to run a TIG welder. I do not have any 220V outlets accessible. Since it is only temporary, I would prefer not to add a permenant 220V circuit. The breaker box is right outside my garage so it is conveniently accessible for the welder.

Is there a proper way to temporarily run a 220V service at the breaker box?

Thanks,

Paul
 
  #2  
Old 03-12-07, 11:52 AM
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Install a 240 volt breaker of the proper size and run the proper size wire for the welder to a properly installed receptacle.

There is no other way to do this.
 
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Old 03-12-07, 12:29 PM
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If you really have no 240-volt receptacle now (e.g., no electric clothes dryer), then Bob's method is really pretty easy. Probably only take you 10-15 minutes to wire it up.

You can certainly make it temporary if you want. When your're done, spend another 10-15 minutes removing what you put in.
 
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Old 03-12-07, 12:40 PM
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As Racraft says, you need to install a proper circuit breaker, run proper cables, and install a proper receptacle. In other words, you need to install a proper circuit.

However because this is temporary, you have some options as to _how_ you do these things.

1) If you have a properly sized breaker for another load that you can temporarily do without, then you can disconnect this other load and cap off its conductors, and then use the breaker to power your welding circuit. For example, if your welder needs a 50A circuit, and you have a 50A range breaker, then eat out for the evening and use that.
Note: you cannot feed _both_ loads.
If the range is fed with aluminium conductors, then study up on proper termination of these.

2) For temporary installations, the requirements for physical protection of the cables are slightly relaxed, for example you don't have to hide romex in the walls, and the support requirements are simply 'supported ...to insure protection from physical damage'. You could even use flexible cord, normally prohibited for building wire, however then you would need a breaker that properly terminates the fine stranding of the flexible conductors. You must still use a proper fitting to support the cable going through the side of the panel. Basically you don't have to spend lots of time stapling and routing the cable, simply make sure that it is protected from damage.

3) You must still use a receptacle in a device box, with proper cable termination.

See article 590 for details on temporary installations. Basically you get a little more leeway, but for the most part the standard wiring rules obtain.

After you are finished, be sure to use a proper plug to seal any holes that you open in your breaker panel.

-Jon
 
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Old 03-12-07, 01:52 PM
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Thanks for the suggestions guys.

The only 220V service in the house is to the A/C out back. It's probably more difficult to access those wires then at the breaker box.

The problem with the breaker box is that wall interior is not accessible from the inside (not even through drywall). If I needed to mount a gang box for a receptacle, I would need to tear through stucco.

I guess what I'm asking is if it's okay to add the proper breakers and hard wire or hang a receptacle off that without intruding into the wall.
 
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Old 03-12-07, 02:11 PM
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Sure, you can surface mount the box. You can probably even mount the box to a temporary stand.
 
  #7  
Old 03-12-07, 02:22 PM
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What you describe would IMHO be a code violation. A rather common one in some areas, and possibly even reasonably safe depending upon the specifics of the situation. However with normal electrical panels, in addition to all of the exposed wires, you will also have exposed bus and bus stabs, meaning metal bars at 120/240V with no protection at all.

At some point you will probably have to deal with ripping through the stucco anyway to run a new circuit, something to consider as a possibility.

I could not recommend simply leaving the front of the panel open with exposed bus bars. However I see no issue if you could properly cover the panel after connecting the wires. You can buy heavy rubber blankets specifically designed to cover exposed electrical hardware. No matter what you do, make sure that you can get to the breakers without risking accidentally touching the live metal.

-Jon
 
 

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