Neighbor's sub-panel

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  #1  
Old 11-01-06, 01:18 PM
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Neighbor's sub-panel

Thanks to the folks on this forum, I have sucessfully installed two sub panels. This does not make me an expert by any means. My neighbor is attempting to install a sub in his detached garage, and what I see does not agree with the philosophy that I've read here in the past. He is hesitant to seek credible advice, so I'll ask on his behalf. Not to one-up him, but what I see is a dangerous install. The circuit is not yet energized.
Garage is approx 100 feet from his house. He is using direct-bury 10/2 wire, fed from a 30 amp double-pole breaker from his main. He has color-coded the white as a black, and has run both to his sub's main lugs. He has taken the ground wire and ran it to his neutral bus. He has bonded another ground bus to the case of his sub, and connected a 6 gauge wire from a 8 foot grounding rod to the ground bus. He has bonded the ground bus to the neutral bus with a piece of 6 gauge.
Any feedback?
 
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  #2  
Old 11-01-06, 02:46 PM
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If there are no other metal paths between the two structures the his installation is legal. By metal paths I mean, water, gas (metal pipe) phone, CATV etc.

Depending on what he wants to do in his shop, the wiring may not be adiquate, but that is a choice for him to make.

I would be concerned about voltage drop, but VD is not a code requirement. IMHO it should be, but it is not as of yet.

Edit to add. The sub cannot be main lugs. There needs to be a disconnect at the seperate structure. This can be the main breaker in a panel, or a seperate disconnect switch.
 
  #3  
Old 11-01-06, 03:25 PM
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So it's o.k. to supply a safety ground via a grounding rod when there is no ground from the source?
It's also o.k. to bond the nuetral bus to the ground bus in a sub?
I don't know for sure, but it would seem that if he threw the breaker to energize the circuit, either the breaker would blow in his hand, or the case of the sub if touched would be hot if current would flow.
I personally would have used 10/3, and not bonded the neutral to the ground bus. I guess this is where my confusion is coming from.
 
  #4  
Old 11-01-06, 03:38 PM
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Originally Posted by Don W
So it's o.k. to supply a safety ground via a grounding rod when there is no ground from the source?
Yes, as long as there are no other metal paths that could create a ground loop.

I would not do it this way. I do not like it. I would not suggest it to one of my customers.

But, it is legal.
 
  #5  
Old 11-01-06, 03:46 PM
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The experts seem to be busy today earning a well deserved living but from my limited knowledge the neutral must be isolated at the subpanel. The ground must be bonded to the panel but not the neutral. It was my understanding bare neutral was no longer permitted in cable but I may be wrong.
 
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Old 11-01-06, 03:55 PM
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Two years of college, four years trade school/apprentiship, 25 years in the trade, a full days exam (twice) and I guess I am still not one of the experts.. HMMMMMMMMM LMAO
 
  #7  
Old 11-01-06, 04:58 PM
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The garage is DETACHED. That allows the three wire feed for the sub panel. If the sub panel was within the main structure a four wire feed would be required.
 
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Old 11-01-06, 05:20 PM
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Sorry Mr. White my comment was ill phrased. I just meant no one here seemed to have caughr the fact the neighbor was using 2-10/G not 3-10 or is a bare neutral (the ground in 10-2) ok? It was when I learned but I thought that had changed.
 
  #9  
Old 11-01-06, 05:51 PM
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no worries ray
The bare neutral is only ok because the only places it is exposed is where the grounds and neutrals are bonded anyway.

Otherwise I would say you have a valid point. Actually you may still have a valid code point, but I will argue the intent of the code for an exception.
 
  #10  
Old 11-01-06, 07:21 PM
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I do not believe that using a bare wire as a neutral is allowed by code.

Further, I say that only a three wire feed is short-sighted and that eventually a second metal path will be added (if one doesn't already exist), and the installation will become unsafe.
 
  #11  
Old 11-01-06, 09:31 PM
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> I do not believe that using a bare wire as a neutral is
> allowed by code.

I thought so too, but have been unable to locate an article specifically forbidding or allowing it, however have found some phrases which support a bare neutral. For example when identifying a neutral, "the ungrounded conductor, if insulated, must be white, grey..." This implies that an uninsulated neutral is allowed, at least in some situations.
 
  #12  
Old 11-02-06, 09:06 AM
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Smiliar setup

Except I plan on running mine in Sch80 PVC with two runs. One is 6awg THWN on a 60Amp double pole. But I will have a parallel run of Sch40 or 80 carrying telelphone, ethernet, and catv. Will I have to bond in this case?

Thanks,
Rob
 
  #13  
Old 11-02-06, 09:12 AM
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You need a four wire feed if you plan on a parallel run of other wires.
 
  #14  
Old 11-02-06, 12:38 PM
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Hmmmmm...code does allow neutrals to be bare we all know that. It can be bare in service laterals it can be bare in service entrance and bare in service overhead on messenger. Seems service wires are covered quite well in that respect. Line side of the main disconnect a neutral can be bare.

I have not been able to locate a code article that would specifically prohibit the use of the bare copper in a UF cable to be used as a neutral. It would seem however that the new rule in 250.119 that says equipment grounding conductors shall be bare, green, or green yellow striped effectively prohibits bare neutrals on the load side of the main disconnect or service equipment. Since bare wires cannot be reidentified as anything but ground on the load side of the main disconnect, I would suspect that Bob is most likely correct.

Roger
 
  #15  
Old 11-02-06, 07:30 PM
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What about the issue of the ground being bonded to the neutral in the sub? I thought that the only place this was allowed was at the service entrance.

But if we're allowed a separate ground at the sub, then I guess it would make sense to bond the neutral there. Hmmm...
 
  #16  
Old 11-02-06, 11:43 PM
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> What about the issue of the ground being bonded to
> the neutral in the sub?

JWhite addressed this in the first reply. A detched building may be fed with 3 wires only if there are no other metallic pathways connecting the buildings. The subpanel in the detached building is then bonded like a main panel.
 
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