Pre-2008 Service Entrance (re: three vs. four wire feeder)

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ompeng

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I am working on a project with an existing stand-alone meter/service entrance panel at the utility transformer (installed prior to 2005) that has two feeders (one to a well pump and one to a cabin). The well pump is still existing and is in use, but the cabin burned down. The feeder to the cabin is about 500' long and is a three conductor with no ground. Currently just sticking out of the ground at the cabin site.

The cabin is being rebuilt, so the question is can I use the existing feeder "as is" to a new grounded subpanel or due I need to run a ground from the service entrance to the subpanel? I believe that the NEC ruling with regard to three versus four wire feedesr changed in 2008.

Thanks for your help.
 
Around here you would have to run the equipment grounding conductor so it would be a re-wire. I would check with the local authority and see how they rule it.
 
ActionDave said:
IMO there is no problem leaving it as three wire, but I'm not your inspector.
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I'm guessing your AHJ would concider this to be new construction not replacement or repair. Therefore it would require being up to code being used in your area. Once you leave the service disconect it is a sub panel and 4 wire would be required. Call your AHJ.
 
Smart $ said:
See the exception to 250.32(B)(1)
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I don't see that argument working.
Currently just sticking out of the ground at the cabin site.
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There's nothing there. Its gone. There is no more "building or structure". If they were doing an addition or what ever then it could stay. Even at that, if there is a metallic water line, phone line or cable installed then that would shoot down the exception. Ask the inspector he is the one that will make the call.
 
If the feeder was existing to a building that is no longer there, then the new building would not be able to use the exception for the existing rule since the new building was not there. That is the way our area sees it.
 
If replacing the existing feeder is going to be very difficult and costly another option would be to install a 240-120/240 transformer at the cabin.
 
curt swartz said:
If replacing the existing feeder is going to be very difficult and costly another option would be to install a 240-120/240 transformer at the cabin.
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Replacing the feeder would be difficult and costly (this is in a rugged location). Please excuse my cluelessness, but how would the installation of a 240-120/240 transformer at the cabin solve the problem?
 
He's suggesting using your existing 3 wire Feeder to feed the primary of a transformer then with proper
bonding, grounding and overcurrent protection, run a 4 wire feeder from the secondary of the transformer
to the new structure.
 
Talk to the ahj and if that doesn't fly maybe you can do away with the disconnect at the pole. This would make the 3 wire compliant.
 
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