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New Member
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Aug 12, 2009, 10:54 AM
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Grounding 3-wire panel in detached garage
I went to install a breaker for an outlet in my detached garage. It has a Square D Homelite panel with a bar at the bottom that connects two nuetral/ground bars, one on each side of the breakers. There are nuetrals and equipment grounds in each of the bars from outlets and such. There is only three wires coming from the house in an underground romex. One wire goes to one main lug, one goes to the other main lug and the third ( a bare wire ) goes to one of the nuetral bars. The other nuetral bar has a wire that goes down to a ground rod right outside the garage.
There is no other connections to the house by any means.
After reading articles on this site and other sites I am wondering if this is a bad thing and what, if anything, could result from this wiring. Or is it OK? Should I get an Electrician to change it and why?
Thank You,
nrl
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Electrical & Lighting Expert
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Aug 12, 2009, 12:45 PM
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You 100% absolutely CANNOT use that cable for a standard 120/240v panel feeder.
All you have is two hots and a ground; or one hot, one neutral and a ground. You simply do not have enough wires for a sub-panel feed.
If the installer though they would be grounding the panel to a ground rod they were sadly mistaken. A ground rod has nothing to do with the circuit grounds.
Who ran this wire?
You need to have a new wire run if you want to have a standard 120/240v sub-panel.
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New Member
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Aug 12, 2009, 01:12 PM
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I don't know who would have installed it. It was there when we bought the house. Everything does work good and I have not had any problems at all. I even have one of the testers you plug in to an outlet. It has the Red & Green LED lights that come on and tell you if the outlet is wired correctly. Both Green lights come on, which means they are correct.
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New Member
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Aug 12, 2009, 01:14 PM
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... but, I do not have anything in the garage that uses 240v so maybe that wouldn't work
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New Member
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Aug 12, 2009, 01:20 PM
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I looked in my Main panel in the house.
There are three wires in there going to the garage. Two wires go to a 50amp double pole breaker and third wire goes to the nuetral bar
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Electrical & Lighting Expert
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Aug 12, 2009, 03:57 PM
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It may work but that does not mean that it is correct or safe. This is an extremely false sense of security.
Many instances of injury and death are documented because of the use of a bare ground wire as a neutral, which is exactly the case in your installation.
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New Member
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Aug 13, 2009, 05:29 AM
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I believe I figured out what I have. The wire run from the house to the garage is old (so is the breaker panel and breaker in the house). Well old? I know it had to be done in 1987 or before because it is under a slab that is between the house and garage and when they poured the slab someone etched 1987 in it. The tag on the breaker panel in the house says "Installed 1972" which is the age of the house.
At some point the previous owner installed a newer panel in the garage. It definitely has two hots and a nuetral (the nuetral is the bare wire, right or wrong) from a 50amp breaker in the house to the panel in the garage. As I said this wire is run under a slab and I am not about to change it. The panel in the garage also has a ground wire run down to a ground rod. From what I read in all the posts on here I think I know what I need to do.
I just would like to know if I am correct (code or not code) to be safe and make sure it is as close to correct as I can get it. (I'll tape the bare wire)
I think I have to mount a ground bar to the panel, move all the equipment grounds to that bar and move the wire from the ground rod to that bar. This would leave only the nuetrals on the two nuetral bars.
I am also just curious to know what could happen, if anything, if left the way it is.
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Electrical & Lighting Expert
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Aug 13, 2009, 12:25 PM
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With a legal 3-wire feeder you DO NOT separate the ground and neutrals. A sub-panel with a 3-wire feeder is treated like a main panel with the neutral bonded to the panel box.
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