Accessory Building

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spark master

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Renovating a 1950's accessory building. barn / garage/out-building. ... Actually torn down to the ground, and being rebuilt from scratch. However, the #6 aluminum feed from house main panel is staying.
2 hots and a neutral direct buried cable.. No grounding conductor goes back to the house service entrance.. main panel.

Obviously I am not bonding the neutral bar in the new sub panel.
But will the inspector accept a ground rod with #6 at the accessory building ?

The expense of trenching 200' back to the house would be a deal killer.

They are trying to preserve the aluminum #6 50 amp feeder to the new out building.

Would a ground rod do it ?
 
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texie

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Fort Collins, Colorado
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Electrician, Contractor, Inspector
spark master said:
Renovating a 1950's accessory building. barn / garage/out-building. ... Actually torn down to the ground, and being rebuilt from scratch. However, the #6 aluminum feed from house main panel is staying.
2 hots and a neutral direct buried cable.. No grounding conductor goes back to the house service entrance.. main panel.

Obviously I am not bonding the neutral bar in the new sub panel.
But will the inspector accept a ground rod with #6 at the accessory building ?

The expense of trenching 200' back to the house would be a deal killer.

They are trying to preserve the aluminum #6 50 amp feeder to the new out building.

Would a ground rod do it ?
Click to expand...

Assuming the AHJ allows the feeder to stay without an EGC, you absolutely MUST bond the neutral at the sub panel in addition to a GES. Failure to do so leaves a very unsafe condition. Do you understand the concept of a fault return path?
 
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spark master

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texie said:
Assuming the AHJ allows the feeder to stay without an EGC, you absolutely MUST bond the neutral at the sub panel in addition to a GES. Failure to do so leaves a very unsafe condition. Do you understand the concept of a fault return path?
Click to expand...

The fault return path is the ground rod.... but I do understand the problem of not having a direct hard wired ground. (EGC)

This sounds like a 10-3 clothes dryer problem.

and now you want to bond the neutral, in a sub panel.... Therefore creating another problem??
 
roger

roger

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spark master said:
The fault return path is the ground rod.... but I do understand the problem of not having a direct hard wired ground. (EGC)
Click to expand...
A ground rod is not a fault clearing path (electricity does not seek the earth) at our voltage levels. Besides 250.4(A)(5) prohibits using the earth as a fault clearing path.

spark master said:
This sounds like a 10-3 clothes dryer problem.
Click to expand...
No in a three wire dryer circuit the neutral is the fault clearing path.

spark master said:
and now you want to bond the neutral, in a sub panel.... Therefore creating another problem??
Click to expand...
You would have to in order to clear a fault but, three wire feeds to out buildings are not allowed any more and it was never allowed if there was a parallel conductive path back the the panel feeding it .

Roger
 
roger

roger

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spark master said:
My referecene to the clothes dryer, was that the frame is bonded to the neutral....
Click to expand...
Correct, it has to be in order to clear a fault, but it is no longer allowed either except for existing installations, if the circuit is changed it has to be a four wire, the same as the feeder to a detached structure.


Roger
 
Little Bill

Little Bill

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Your AHJ may allow the feed to remain IF there are no other metallic paths between the main and the separate building. If he does allow it, You MUST bond the neutral and EGC at the 2nd building along with a GEC system, be that a ground rod or other acceptable means. You would have no fault clearing path if something shorted to a conductive surface such as a metal box, frame of dryer, etc. if you didn't bond it. And no, as Roger said, the rod will not clear a fault.
 
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spark master

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ok... so let's play devils advocate.
What if you get an open neutral between the house, and the accessory building ?

Then you have floating neutral voltage on the ground system of the barn... correct ?
 
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Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
spark master said:
Renovating a 1950's accessory building. barn / garage/out-building. ... Actually torn down to the ground, and being rebuilt from scratch. However, the #6 aluminum feed from house main panel is staying.
2 hots and a neutral direct buried cable.. No grounding conductor goes back to the house service entrance.. main panel.

Obviously I am not bonding the neutral bar in the new sub panel.
But will the inspector accept a ground rod with #6 at the accessory building ?

The expense of trenching 200' back to the house would be a deal killer.

They are trying to preserve the aluminum #6 50 amp feeder to the new out building.

Would a ground rod do it ?
Click to expand...


I'm with Little Bill. It was legal when it was done. However, the extent of work you are doing stretches the meaning of grandfathered in. If your AHJ is really forgiving he might allow it. I don't think I would if I were an AHJ.
 
roger

roger

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spark master said:
ok... so let's play devils advocate.
What if you get an open neutral between the house, and the accessory building ?

Then you have floating neutral voltage on the ground system of the barn... correct ?
Click to expand...
So what happens if you have an open neutral between the utility transformer and a house?

Roger
 
infinity

infinity

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Location
New Jersey
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Journeyman Electrician
spark master said:
Renovating a 1950's accessory building. barn / garage/out-building. ... Actually torn down to the ground, and being rebuilt from scratch. However, the #6 aluminum feed from house main panel is staying.
2 hots and a neutral direct buried cable.. No grounding conductor goes back to the house service entrance.. main panel.

Obviously I am not bonding the neutral bar in the new sub panel.
But will the inspector accept a ground rod with #6 at the accessory building ?

The expense of trenching 200' back to the house would be a deal killer.

They are trying to preserve the aluminum #6 50 amp feeder to the new out building.

Would a ground rod do it ?
Click to expand...

IMO you have two choices, a new feeder or converting the existing 3-wire feeder to 120 volts. What kind of direct buried cable is existing?
 
readydave8

readydave8

re member
Location
Clarkesville, Georgia
Occupation
electrician
spark master said:
Renovating a 1950's accessory building. barn / garage/out-building. ... Actually torn down to the ground, and being rebuilt from scratch.

The expense of trenching 200' back to the house would be a deal killer.
Click to expand...

existing building was not worth saving but 60 year old DB AL is?

I think this is a sales problem, not a technical problem
 
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