Sub Panel in detached garage

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Old 02-20-10, 12:11 PM
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Sub Panel in detached garage

I have installed a sub panel in my detached garage. I ran 6-3 romex with a bare ground inside schedule 40 pvc burred 24 inches between my main panel and my garage. My main panel has a shared neutral/ground bus. I attached the neutral and ground to the shared bus on the main panel and attached the two hots to a 50-amp 2-pole breaker. At the sub panel I attached the two hots to the main lugs, the neutral to the neutral bus bar, and the ground to a separate ground bar. I have two questions:

1. Am I correct in keeping the ground and neutral separate in the sub panel?

2. Do I need to drive a ground rod for the garage panel?
 
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Old 02-20-10, 12:24 PM
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Yes the neutrals and grounds need to be on separate isolated busses.

Yes you need a ground rod.

The issue is that NM cannot be used in wet locations. The NEC very clearly states that conduit outside is a wet location. You should pull out the NM and install individual THWN conductors.
 
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Old 02-20-10, 01:51 PM
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Also, if your garage circuit breaker panel can be fitted with more than six circuits you need a main breaker or disconnect.
 
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Old 02-20-10, 01:51 PM
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What a bummer... that was a lot of work.
 
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Old 02-20-10, 08:49 PM
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In addition, NM cable is a cable assembly and cable assemblies are not allowed to be installed in a raceway such as conduit unless it's a short sleeve length at the ends for additional protection.

If you fit the panel with a main breaker by plugging a 2 pole breaker on the bus, it technically by code must also be fitted with an approved retaining clip.
 
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Old 02-21-10, 11:00 AM
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Originally Posted by pcboss View Post
Yes the neutrals and grounds need to be on separate isolated busses.

Yes you need a ground rod.

The issue is that NM cannot be used in wet locations. The NEC very clearly states that conduit outside is a wet location. You should pull out the NM and install individual THWN conductors.
Not to mention that you are not allowed to pull Romex wire or any jacketed wire for that matter(SE,SER,UF,NM) through any conduit. It is considered a raceway inside of raceway and is illegal.
Second, becuase this is a detached structure and there is no metallic connections between the 2 buildings, you can actually install that panel as a main panel. You would run just 2 hots and neutral, and ground at the new main accordingaly. 2 ground rods. The grounds and neutrals wouldnt be seperated in this panel, it is treated as a main panel and it would need a main breaker.
 
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Old 02-21-10, 11:54 AM
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Originally Posted by ElectricJoeNJ View Post
Not to mention that you are not allowed to pull Romex wire or any jacketed wire for that matter(SE,SER,UF,NM) through any conduit. It is considered a raceway inside of raceway and is illegal.
Second, becuase this is a detached structure and there is no metallic connections between the 2 buildings, you can actually install that panel as a main panel. You would run just 2 hots and neutral, and ground at the new main accordingaly. 2 ground rods. The grounds and neutrals wouldnt be seperated in this panel, it is treated as a main panel and it would need a main breaker.
Joe .,

I am not going to argue with ya but can you cite me the NEC code art number that allow this set up ??

Due majorty of the area I know they will no longer honer 3 wire feeder set up and in State of Wisconsin it do not allow 3 wire feeder to detached building anymore and in France it will allow 3 wire feeder only if you have line et netual loads plus earth { ground } however if you have line to line loads then you must use 5 wire feeder due it is triphase supply.

Merci,Marc
 
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Old 02-21-10, 05:27 PM
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Originally Posted by french277V View Post
Joe .,

I am not going to argue with ya but can you cite me the NEC code art number that allow this set up ??

Due majorty of the area I know they will no longer honer 3 wire feeder set up and in State of Wisconsin it do not allow 3 wire feeder to detached building anymore and in France it will allow 3 wire feeder only if you have line et netual loads plus earth { ground } however if you have line to line loads then you must use 5 wire feeder due it is triphase supply.

Merci,Marc
I will dig up the NEC code for you tomorrow. I know its in the 05 and 08 code books. i had a situation where i was pulling a feeder from a building to a detached pump house. the feeder was coming from a transformer through a fused disconnect inside the building. My guys forgot to attach the ground to the wire pull, seeing as it was over 200 feet we didnt want to pull it back out. Thats when i found the code, and i had it checked out through the AHJ and he said it was perfectaly legal. I will look it up tomorrow and get back to you.
 
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