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-   -   Detached Garage Wiring (http://www.diychatroom.com/f18/detached-garage-wiring-118081/)

elpht_man 09-22-2011 11:52 PM

Detached Garage Wiring
 
I am closing on a house in two weeks and it has a detached three stall garage that doesnt have any power. In my simple rookie mind I thought that I would run a 20 amp line for the outlets and a 15 amp line for the lights, and to operate the two garage doors. I was planning on having two individual breakers at the main panel and running one 12 awg and one 14 awg through conduit. I was also planing on using THWN wiring instead of UF and branching off of a junction box in the garage instead of using a sub panel. The conduit would only have to run about 40 feet and once inside the house the main panel is only about an addional 20 feet away. Now that I have read some posts I see that much of this is wrong. I have seen many posts that have helped me out but I dont feel like any of them have specifically answered the questions that relate to my specific situation. Any advice would be appreciated.

I guess these are my questions....

Will I need a sub panel for a disconnect since I have more than one circuit?

Will I need a grounding rod?

I am quite certain that my wiring to the garage is incorrect. What should I run to support my 15 and 20 amp circuit?

Is it alright to run THWN through conduit instead of UF?

Thanks in advance!

gregzoll 09-23-2011 12:01 AM

Search this forum. There have been hundreds of threads about what you are wanting to do. For a garage that size, I would personally put each opener on its own circuit, depending on how much lighting you are going to have in there, 15 amps may not be enough. If I was going to be doing it, I would go for a 100 amp sub-panel, due to you never know what you may want to do with that beast of a garage.

matt151617 09-23-2011 06:47 AM

If you're closing on a house you probably don't have a ton of extra money. I would start simple. Go pick up a large roll of 12g NM and one of 14g. They come in 25, 50, 100, and 250ft rolls, I would get the 250. You can never have too much extra wiring once you own a house and it's surprising how fast it'll run out. Pick up a small subpanel, they're very cheap. When you run conduit get much larger than you need so you can upgrade down the road. Also put down another run of smaller conduit next to it so you can add cable, phone lines, etc. Don't forget all the other essential items: lots of j-boxes with covers, outlet boxes, outlets and covers, light switches and covers, twist connectors, electrical tape, NM ripper tool, circuit tester, wire stripper, staples, etc. I would also pick up a book on basic wiring while you're getting the other stuff and read it over before starting your project.

I would say run 10/3 THWN or UF unless you plan on running a lot of amps out there. 60 will give you plenty of juice. You do need a subpanel, no branching off of circuits through j-boxes. Depending on the amp draws of whatever lighting and openers you put in run 14g or 12g romex. Remember the outlets need to be gfic protected either through a gfic breaker or on a gfic outlet that's first off the subpanel.

To answer your questions:

- Yes you need a subpanel. Only one feeder line is allowed in to the garage.
- Grounding rod isn't needed. Couldn't hurt though if you feel like putting one in. Better to put it in now when everything is dug up.
- See my above. Run 10/3 to a subpanel and branch off of that.
- THWN is individual wires designed for being in conduit. UF is PVC coated Romex designed for direct bury (not in conduit).



Also: go to the post office and ask for a change of address kit so they'll forward mail from your old house. Inside is usually a 10% off coupon for Lowes which will save you quite a bit of money. The wire alone will run you about $300 and everything else could be $100-$200.

kbsparky 09-23-2011 07:03 AM

Quote:

Originally Posted by matt151617 (Post 734333)
....

- Yes you need a subpanel. Only one feeder line is allowed in to the garage.
- Grounding rod isn't needed. Couldn't hurt though if you feel like putting one in. Better to put it in now when everything is dug up. ....

Ummm ... IF you put in a sub-panel, THEN you NEED ground rod(s)! (or other suitable grounding electrodes)

If you install only one circuit to a garage (including a multi-wire circuit), then a sub-panel is NOT needed, nor a ground rod.

rjniles 09-23-2011 07:31 AM

If the OP is in the US he needs ground rods, if Canada apparently not.

matt151617 09-23-2011 07:31 AM

Quote:

Originally Posted by kbsparky (Post 734336)
Ummm ... IF you put in a sub-panel, THEN you NEED ground rod(s)! (or other suitable grounding electrodes)

If you install only one circuit to a garage (including a multi-wire circuit), then a sub-panel is NOT needed, nor a ground rod.

Yeah right sorry, got turned around on that one. Ground rod with subpanel (per code, but it's still grounded by a ground rod at the house technically).


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