center tap delta grounding

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RowE

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I saw an install yesterday on a 4-wire 120/240v center tap delta. I?m not sure about the grounding of this type service. From the service disconnect to the house disconnect 200? away they ran five wires (3 ungrounded , a neutral, and an equipment grounding conductor). The neutral and the equipment grounding conductor where bonded at the service disconnect and at the house disconnect which was using the A&C phases 120v to ground . Wouldn?t this create a parallel path back to the service? Does the neutral and equipment grounding need to be unbonded or does it even need the fifth wire.
 
RowE said:
I saw an install yesterday on a 4-wire 120/240v center tap delta. I?m not sure about the grounding of this type service. From the service disconnect to the house disconnect 200? away they ran five wires (3 ungrounded , a neutral, and an equipment grounding conductor). The neutral and the equipment grounding conductor where bonded at the service disconnect and at the house disconnect which was using the A&C phases 120v to ground . Wouldn?t this create a parallel path back to the service? Does the neutral and equipment grounding need to be unbonded or does it even need the fifth wire.
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The neutral and EGC need to be be isolated from each other at the house. All five conductors are required unless utilizing a metal raceway as the EGC.

Are they even using the third (B) ungrounded conductor? If not, it is not required... but not prohibited, either.
 
Smart $ said:
The neutral and EGC need to be be isolated from each other at the house. All five conductors are required unless utilizing a metal raceway as the EGC.

Are they even using the third (B) ungrounded conductor? If not, it is not required... but not prohibited, either.
Click to expand...

Yes, the 3 phase feeds a grain elevator. pretty small load 30-40A
 
Smart $ said:
The neutral and EGC need to be be isolated from each other at the house. All five conductors are required unless utilizing a metal raceway as the EGC.

Are they even using the third (B) ungrounded conductor? If not, it is not required... but not prohibited, either.
Click to expand...

I agree. I might add that the OP needs a GES at the house connected to the EG bar in the disco.
 
FWIW, I have one customer that has a delta service as described at two of his farm locations. The residence or house is fed from only the single phase center tapped transformer although all three phases of the delta bank are at the farm ( house) disconnect in the yard. We do not normally consider that disconnect as service equipment so for his existing installation it is 3 wire to the house and 4 to the grain handling equipment. Four and five wire for Texas.
 
RowE said:
I saw an install yesterday on a 4-wire 120/240v center tap delta. I?m not sure about the grounding of this type service. From the service disconnect to the house disconnect 200? away they ran five wires (3 ungrounded , a neutral, and an equipment grounding conductor). The neutral and the equipment grounding conductor where bonded at the service disconnect and at the house disconnect which was using the A&C phases 120v to ground . Wouldn?t this create a parallel path back to the service? Does the neutral and equipment grounding need to be unbonded or does it even need the fifth wire.
Click to expand...

2005 and prior one could "rebond" the neutral between structures with a few conditions. If that were the case, it would change what you saw from a neutral/ground non-separation violation to a probable incorrect parallel conductor installation. Is it a simple matter to lift the Bond at the house?
 
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