garage

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Old 08-24-09, 11:07 AM
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I am wiring a new two car detached garage.Will have garage door openers,incandescent lighting and outlets.This is a bare bones garage and will not be used as a workshop.What are the requirements?
 
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Old 08-24-09, 11:30 AM
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Barebones requirements for the garage are:

1) At least one GFCI general-purpose receptacle (15A or 20A) mounted no higher than 6'-6" from the floor. Some jurisdictions require a minimum height of 24" from the floor, but that's not universal. I prefer about 48 - 50" so that sheet goods or storage don't obstruct it.

2) At least one switched interior light. It's only required to be switched at one location, but typically you would do a three-way or four-way switch so that it can be turned on from any of the entrances.

3) A switched light outside each exterior human door (vehicle doors do not require exterior illumination)

4) Door opener receptacles must be GFCI protected
 
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Old 08-24-09, 03:18 PM
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So what size circuit do I run and how many/
 
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Old 08-24-09, 04:36 PM
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A 20 amp circuit should be enough. Is this an attached garage?
 
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Old 08-24-09, 05:21 PM
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garage

It is a two car detached garage
 
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Old 08-24-09, 07:18 PM
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You will either need to bury UF cable or run conduit. Conduit may be a better choice. If you ever need to increase your power it will be easy to pull new wires.

UF is easier to install but has to be replaced if you need more power. A detached garage can only have one circuit but there is a loop hole a multi-wire circuit can provide two 20amp circuits. With UF you would use three conductor and a 240v breaker to provide two 120v 20a circuits. That would be over kill but it gives you built in extra capacity for the future with only slightly higher cost.

When you decide what you want to do tell us and we will walk you through it.
 
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Old 08-25-09, 11:53 AM
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garage

If I run a 12/2 to the garage can I split into two 15Amp circuits or should I run two seperate 14/2
 
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Old 08-25-09, 12:42 PM
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No, a 12/2 cannot split into two 15A circuits, and only one circuit is allowed to an outbuilding.

I think your options are basically:

1) Run a single 20A circuit 12/2 UF-B cable to the garage. It meets your needs, but does not exceed them with no room for expansion. Very straightforward to install, cheapest on materials and labor. Requires a 24" trench with a standard breaker or 12" trench with a GFCI breaker.

2) Run a multiwire 20A circuit 12/3 UF-B cable to the garage. It meets your needs with a little room for expansion to handheld power tools and small power equipment, provides double the power as option 1. Only slightly more expensive and slightly more complex to install than option 1 and basically the same on all other points.

3) Run a 3/4" PVC conduit to the garage and pull through conductors to mimic the functionality of either option 1 or 2. Somewhat higher cost and labor, but room to expand to a 60A service in future which would accommodate a full workshop. Also provides a bit of extra protection for the wire and reduces the trench depth to 18".

My recommendations in order of preference would be #3, #2, #1. The cost difference between #3 and #1 is not significant and the labor is basically the same. Small price to pay for future flexibility.
 
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Old 08-25-09, 12:52 PM
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If you run a 12/3 you can get two 15A or 20A circuits from that. You cannot run two separate cables, that implies two separate circuits, which is forbidden.

It is bad form to extend #12 wiring with #14, although not against code if the #12 is protected with a 15A breaker. I'd go #12 throughout. Wire is cheap now.

You will also need an entrance disconnect. This can rage from a two pole switch, to an unfused or fused A/C disconnect. I like using the type of switch that uses two screw in fuses, or a small 4 to 6 breaker panel.
 
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