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-   -   Wiring up 220 for my welder in my new garage (http://www.risingsun4x4club.org/forum2/showthread.php?t=16527)

Rezarf 09-22-2011 12:42 PM

Wiring up 220 for my welder in my new garage
I am looking for some advice. I am trying to get a 220v line to my garage for my welder and (future) compressor. We just replaced our electric stove with a gas unit and I now have a perfectly good 220v 50amp circuit and wire just sitting there in the wall unused.

I ran my last 220v line from my fuse box to an outlet in the garage so I am not in totally new water here. However, I would like to run this by those smarter than myself.

If you pictured my house as a square, my stove is on the rear exterior wall. If I punch a hole through the exterior (which is where the existing outlet already sits, it just faces the interior) and pick up the circuit there, shouldn't I be able to run some conduit on the exterior of my home around to the garage (front right corner of the house when facing it). I figure the run of new cable to be about 65' and I would like to break off into two outlets one dedicated for the compressor and one for the welder, though the two will not be run at the same time.

Does this sound correct?

How do I start to figure out what gauge style wire I need? Thanks in advance-


nuclearlemon 09-22-2011 01:07 PM

i have one 220 that i alternate the welder and the compressor off of. i found that, since the welder always needs to be away from the corner where the compressor is, the easiest setup was an extension cord plugged into the 220 outlet and i alternate the compressor/welder from that. then i easily store the cord at the base of the compressor. this way, i can use the welder out in the driveway if i need.

Air Randy 09-22-2011 01:13 PM


Where is your AC distribution panel located? Rather than run a circuit from the existing receptacle location, run the circuit from the breaker panel itself especially if it is closer. As long as you have expansion space in your breaker panel, it is also very easy to add additional 220 breakers so you could have a dedicated circuit for both the compressor and the welder.

You can do what you propose very easily but you will need to use emt or rigid conduit and weatherproof fittings since it would be on the exterior. If you can run all of the circuit inside the house by going from the breaker panel you can useemt, pvc or even direct install without conduit.

The shorter the run of the circuit, the smaller the gauge of wire you can use. You will find the cost of wire per foot shoots up when you go from say 12ga to 10ga. It is like long thin sections of gold.

I've done a lot of wiring like this and I know how to do it so it is code compliant, if you need any help let me know.

I would have to look it up to be sure but I believe for a 50a circuit you need to use a 3+1 conductor 10ga wire when the run is 100' or less. Keep in mind too that 50a is probably way more than what you need for a compressor or newer welder. Usually a 30a circuit at 220v is more than enough. This can make a significant difference in the size/cost of the wire you use.

Beater 09-22-2011 01:38 PM

stop by my house, and you'll see how I ran 70amp to my out-building according to code, suspended and all.

Rezarf 09-22-2011 01:38 PM

Thanks guys, Randy, we don't have AC just a swamp cooler (which actually really impressed me on a few hot days).

I have a blank spot on my breaker labeled "Garage" that has been scratched out. I have searched high and low and can't find anything in the garage that would allow 220v access. The blank spot has two circuits marked off (for 220v) but they have a blank cover no breaker installed.

Ige, I like that idea a lot. I will most likely run a 220v outlet for the compressor into the attached shed behind the 3rd garage (where I will keep the compressor to cut the noise down) but I will most likely punch through the wall dividing the shed/garage and install one more outlet on the interior of the garage... along with an on/off switch to control the compressor power.

Jacket 09-22-2011 02:06 PM

Do you have a basement that you could run the wiring instead of outside?

When I added my 220v, I did like Randy is suggesting. I left my dryer circuit as is, and dropped in a new 30 or 40A (can't remember) breaker to the panel, and then ran a short line of hard conduit through the wall and into my basement. I had something like 75' of wire to get from the panel to my garage, and I can't remember what I gauge I used - but I can check. I want to say it was 8g and it was pretty $$.

Air Randy 09-22-2011 02:28 PM

[quote=Rezarf;192338]Thanks guys, Randy, we don't have AC just a swamp cooler (which actually really impressed me on a few hot days). QUOTE]

AC distribution panel = breaker panel

HVAC = air conditioning :D

frontrange 09-22-2011 03:36 PM

Copper will cost you an arm and a leg these days, I know because I just wired my new shop. Aluminum is way cheaper, but you cannot use it in a residence except between a main panel and a sub panel, which IMHO is a better way to go to power a shop.

I had electricians install a 70 foot 100 amp run through the attic to an 8 circuit sub panel in the basement for about $500 including parts just for reference, then I did a few short drops with large gauge copper from the sub panel to the compressor, welder and the machine tools.

Rezarf 09-22-2011 10:56 PM

[quote=Air Randy;192348]

Originally Posted by Rezarf (Post 192338)
Thanks guys, Randy, we don't have AC just a swamp cooler (which actually really impressed me on a few hot days). QUOTE]

AC distribution panel = breaker panel

HVAC = air conditioning :D


My breaker panel and garage are at the two opposite corners of the home. What a pain. I could drop the 50amp line inside into the basement since it is not finished and I can pull wire through it with ease. My dryer however is about 4' from the garage and would be a piece of cake to drop a circuit there.

Dave, I am in Broomfield now, not Louisville anymore if it makes a difference. And yeah, I pull permits... if I burn the place down they could come in handy ;)

DaveInDenver 09-22-2011 11:58 PM

Unlikely to matter, I doubt any municipality has adopted the 2011 NEC yet and the vast majority of 2005, 2008 and 2011 hasn't changed.

FWIW, a 20% or less duty cycle allows an arc welder to be supplied based on 0.45 multiplier to the plate rating. So if the welder is rated 45A that means you only need to size the branch for 21A and can use a breaker sized at 200% of the conductor rating. Just don't exceed 2 minutes of use every 10. Even at 50% duty you can use a 0.71 multiplier and use a 30A sized branch.

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