Garage Wiring


Old 11-04-05, 06:56 AM
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Lightbulb Garage Wiring

I am getting ready to run a sub panel out to our garage. The distance from the main breaker box in the house to the garage is less than 100'. My question is since I am going to run 220v out from the main to the garage then run seperate 110v and 220v outlets out of the sub, what gauge wire should I use for the main run to the garage. I have had some people tell me 8 gauge will do fine, and others tell me to run at least 6. I do have an older Lincoln Arc welder out there that I would like to use on occasion, and of course that runs on 220v. Currently the service that is out there is only 110, on a 12 gauge, 3 wire feed, but when I run my 110v air compressor and ANYTHING ELSE that draws more than say 5 amps it blows the breaker in the house. I am going to bury whatever I use underground in 2" PVC conduit, so I am open for suggestions. Thanks
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Old 11-04-05, 07:08 AM
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One comment. Once you connect up your sub panel, you will have to abandon the existing feed to the garage by disconnecting at both ends. You can route it into your sub panel in the garage if you want to keep the circuit, but you must remove it as a circuit from the main panel.

The size wire you use depends on the size sub panel you plan to install and on the size of the breaker in the main panel that will be feeding the sub panel. If you use 8 gage wire then you can use nothing larger than a 40 amp breaker.

Only you can decide what your needs are. Start with the welder. What are itís current requirements? You need at least that much, plus enough for whatever else will be running at the same time, which is probably at least lights.

Are you planning on a three wire or a four wire feed to the sub panel? Donít forget ground rods at the sub panel.
Old 11-04-05, 07:10 AM
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Someone said #8 will be fine. They should have said it *may* be fine.

As a DIY'er, you should be spending more time planning than doing, IMO.
You need to first calculate your anticipated load, which is AMPS.

If you need help determinnig load, then you need to tell us everything you plan to use. Consider lighting, general purpose recepticles, the tools and appliances you currently have, and those which you would like to account for now.

Also, you'll need to know what service you have coming in to your house, and your approximate load. If your service is 150A, and you're using 100A, then you have up to 50A that you can run at one time in your garage. That's at one time. You could still have a 100A subpanel, but it's peak use can't top 50A.

HTH...At least a little...

Old 11-04-05, 07:13 AM
Join Date: Feb 2002
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I advise 100 amp conductors if you are proposing to operate a welder.Voltage-drop, as compared to the amp-rating of the conductors may be a factor with that specific type of load.

Calculate the cost-difference between X-ft of #6 copper vs. #3 copper. You are being astute by installing a 2" raceway.
Consider a seperate R-W for communication-cables.

You will need an Green Equiptment Grounding Conductor in addition to the 3 Feeder Conductors, and a Ground-rod at the detached structure.

Good Luck, & Learn & Enjoy from the Experience!!!!!!!
Old 11-05-05, 11:07 PM
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Originally Posted by PATTBAA
You will need an Green Equiptment Grounding Conductor in addition to the 3 Feeder Conductors, and a Ground-rod at the detached structure.
you will only need a ground conductor from house to garage if there is some other continous metallic conductor from house to garage. as long as you eliminate the current circuit from the house, and there is no other circuit coming from the house (or water or gas lines, for example), you need a ground rod at the subpanel and bond the ground and neutral in the subpanel.
the less distance stray voltage has to travel, the better.

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