Rewire Detached Garage

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Old 05-26-08, 09:54 AM
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Rewire Detached Garage

Hey-

I'm looking to rewire my detached garage. Currently there is a 20 amp circuit that runs out there, with 12 gauge wire.

The end result that I'm looking for is:
3-4 overhead lights (maybe fluorescent someday)
2 outdoor lights
3-4 20amp receptacles

I have a couple questions for the crowd:
1. How do I go about running wire over the roof trusses. Its 4' between, can I just staple it to each truss, or do I need conduit?
2. With how expensive wire is, is it advisable to reuse some of the old wire out there (insulated w/metal jacket, no ground wire)? Obviously if I did I would use metal boxes etc...

3. I've never been clear on this. What considerations are there for bringing 12ga and 14ga together? I was thinking of using 14ga for the lighting since the 12ga is a bit overkill... Is there anything to keep in mind when doing that, or can I just connect the two together?

Thank you in advance!
 
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Old 05-26-08, 10:21 AM
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Originally Posted by ande3171 View Post
Hey-

I'm looking to rewire my detached garage. Currently there is a 20 amp circuit that runs out there, with 12 gauge wire.

The end result that I'm looking for is:
3-4 overhead lights (maybe fluorescent someday)
2 outdoor lights
3-4 20amp receptacles

I have a couple questions for the crowd:
1. How do I go about running wire over the roof trusses. Its 4' between, can I just staple it to each truss, or do I need conduit?

You could install a running board to each truss and then staple the wires to this strip or staple to the trusses.


2. With how expensive wire is, is it advisable to reuse some of the old wire out there (insulated w/metal jacket, no ground wire)? Obviously if I did I would use metal boxes etc...

What is the vintage of the metallic wire? Does it have a thin bond wire in it? Look to see if it is wrapped around the outside of the jacket at the terminations. The old wire may not be listed for use as a grounding means, if so you may not extend an ungrounded circuit.

3. I've never been clear on this. What considerations are there for bringing 12ga and 14ga together? I was thinking of using 14ga for the lighting since the 12ga is a bit overkill... Is there anything to keep in mind when doing that, or can I just connect the two together?

The two can be connected together using twist-on wire connectors. The breaker or fuse would then need to be changed to a 15 amp to protect the smaller conductor.

Thank you in advance!
What do you intend to use in the garage? Perhaps a small subpanel would be a better option.
 
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Old 05-26-08, 10:36 AM
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Nothing too serious. A smaller air compressor may be in the works for the future (something like a 26 gallon, 1.6 hp).

Other than that, maybe a miter saw from time to time, and then just lighting for working on the cars.

By sub panel, do you mean a heavier service like 30-50 amps, and then having a breaker box in the garage to pull everything from?
 
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Old 05-27-08, 04:20 PM
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I figured out the answer to number 3 (20 amp circuit requires 12ga from end to end)

Anyone have an answer to the first two questions?
 
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Old 05-28-08, 08:41 AM
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Originally Posted by ande3171 View Post
How do I go about running wire over the roof trusses. Its 4' between, can I just staple it to each truss, or do I need conduit?
As long as there is no chance of damage from foot traffic or storage, you can staple every 4'. Maximum distance between staples is 4'-6". If the ceiling area is accessible for storage or other traffic, nail a 2x4 perpendicular to the trusses and staple the NM-B (Romex) to that.

With how expensive wire is, is it advisable to reuse some of the old wire out there (insulated w/metal jacket, no ground wire)? Obviously if I did I would use metal boxes etc...
You cannot re-use this cable because it has no ground conductor. Modern MC (metal cable) has a ground wire, and modern AC (armored cable, BX) has a bonding strap to satisfy the ground requirement. Additionally, once you start flexing cable that has been installed for years, the insulation can get brittle and crack off. Your best option is to sell it at the metal recycler.

I've never been clear on this. What considerations are there for bringing 12ga and 14ga together?
If there's #14 anywhere in the circuit, the breaker must be 15A. If a circuit mixes wire gauges, the breaker must match the smallest wire.
 
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