I have an unusual situation, at least for me. I have to provde a temporary service to an office trailer, which involves running 480V., 80A. single phase from a panel in a building a distance of 1250' underground to the trailer. I am going to use direct burial single conductor 4/0 aluminum to keep the cost down. At the trailer I will use a transformer to step it down to 120/240 single phase. My main question is: do I need to run a ground wire with the primary phase conductors from the building to the trailer? I don't believe it is necessary since I will be creating a neutral at the trailer by bonding XO to the frame of the trailer, and driving a ground rod which will, I believe, also be connected at XO (correct me if I'm wrong). Any input on this matter would be greatly appreciated.
Grounding on Transformer Primary Side
- Thread starter samcon
- Start date
- Status
- Location
- Massachusetts
samcon said:
Yes, you must bring a grounding means with the circuit conductors from the source and connect it to the transformer enclosure.
It is still necessary, all the work you describe only provides protection for faults on the secondary side of the transformer.
The EGC you must run from the source is to protect against primary side faults. As in a primary winding to case fault.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
iwire said:
Absoloopy!
- Location
- Bremerton, Washington
Samcom, on the primary side you need an EQC so in the event of a line to case fault on the primary side the fault current can return to its source. The secondary has a system bonding jumper, for return of secondary fault current to its source, the transformer.
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