Detached Garage Subpanel questions

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Old 12-22-11, 11:15 AM
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Detached Garage Subpanel questions

I recently got married, and my new wife's residence where we are living has a detached garage with a subpanel that feeds from a 20amp breaker in the main house electrical panel. The existing garage subpanel is an outdated mess with a main breaker and 2 fuses, and uncovered, spliced wires. A true disaster waiting to happen. It's my first time doing something like this, but my gut tells me that something's gotta be done considering the existing wiring's present state. I'd like to do it myself, since danger of hurting myself seems minimal since I can shut off the power to the garage using the 20amp breaker in the main house electrical box.

I want to update the subpanel in the garage in order to make it safer. The garage isn't used as a work area - it's just for parking. I'm planning on tearing the existing subpanel out, and all the spiced wiring, and starting over. My plan is a new subpanel, 3 flourescent lighting fixtures hooked to one switch; and 3 plug outlets. There is a shed attached to the back of the garage with 3 lights, one outlet and a switch that also feeds off the garage subpanel. This all needs rewired also, and I'm planning on putting the shed on its own breaker in the garage subpanel.

My questions are:

1. Can the 20 amp breaker on the main house electrical panel feed all of this? There's no appliances in the garage, again it's just used for parking.

2. Can you recommend a subpanel for me to buy at Lowe's or Home Depot, and what kind of breakers (15 amp maybe?) do I need for the flourescent lights and the plug outlets?

Thanks!
 
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Old 12-22-11, 12:05 PM
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You don't need a subpanel. You could replace the existing cable from the house to the garage with 12-3 UF on a 20a 240v breaker and have two 120v circuits at the garage without using a subpanel. If that interests you post back for details.

Above assumes existing supply cable needs replacing also. If it is in good condition and 12-2 or larger you could run everything on a single 20a circuit no breaker box needed.
 
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Old 12-22-11, 02:33 PM
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Thanks Ray. Yes the supply cable is in good condition. I'd like to have the subpanel for setting up the shed and garage on seoerate breakers. If I put the subpanel in, can i use the 20 amp main box breaker given my simple needs here?

Also, what amp breakers would you recommend for lights and outlets? Anything else I'm missing? A ground is present in the existing garage panel running from the garage panel along the outside of the garage wall and into the driveway.

Thanks - this is my first time setting up a panel so Please forgive any lack of understanding with terminology. With my lack of experience, I'd never touch the main panel in the house.
 
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Old 12-22-11, 02:40 PM
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You just don't need a sub panel. There is nothing to be gained by using one. Everything you want to do can be done in a junction box with a simple switch to disconnect the incoming power. The switch would be nothing more then a good quality 20a "light" switch.

A ground is present in the existing garage panel running from the garage panel along the outside of the garage wall and into the driveway.
Do you mean the cable coming to the garage does not have a ground wire in it? What type of cable is it, UF or what? Is it buried? Is it 12-2 or 12-3 or what?

12-2 would be black, white, bare. 12-3 would be black, red, white, bare.
 
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Old 12-22-11, 03:25 PM
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The cable running from the 20 amp breaker in the main house electrical panel goes underground across a driveway, through the shed built onto the back of the garage to the existing subpanel inside the garage. It's a white, flat cable...sorry don't know more. It may have a ground wire in it - I don't know. I would guess 12-2 but i'm not sure. The ground wire I was speaking of is on the outside of the garage wall opposite of where the existing garage subpanel is. I just assumed it was the ground wire since it goes into the driveway in front of the garage.

I wonder why the existing subpanel was put in the garage in the first place. It just has a two main pull-type breakers and 2 fuses and looks like it may have been installed in the 50s. Maybe my father in law installed it but he's 85 and has some age related problems with his memory. My wife is 48 and remembers that panel always being in the garage. She also says the previous owners may have installed it prior to her parents moving here in 1952.
 
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Old 12-22-11, 03:28 PM
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Sorry to clarify... A new house and main panel in the house Was built in 2003. The old garage remains from the original house. Cable from the house panel to the garage subpanel is new.
 
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Old 12-22-11, 05:43 PM
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Considering the lighting loads a 15 amp circuit with #14 gauge wires would be fine. For receptacles I would use #12 with a 20 amp breaker.

The receptacles will need GFI protection.
 
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Old 12-22-11, 07:27 PM
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This may be UF cable that has faded. I would like to know more before the OP proceeds with possibly the wrong type of cable installed.
 
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Old 12-23-11, 04:53 AM
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On the outside of the cable that runs from the house panel 20 amp breaker to the panel in the garage, it says 02-03 UF-B SUN-RES 12/3 N/C CIRTUF-A 1UL NT/MRL
 
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Old 12-23-11, 05:22 AM
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Thanks, that style of cable is listed for use outside and underground. You could use it to run a 20 amp mutiwire circuit to the outbuilding. Use either the black or red for the lights and the other for the receptacles.

A double pole single throw switch could be the means of disconnect where the power enters the building. As this is considered a single circuit you will not need a ground rod.
 
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Old 12-23-11, 07:22 AM
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Rich now that I know the cable you have is correct I have deleted my post that it may be incorrect. Sorry for any confusion.
 
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