SteveFehr
Electrical
- Dec 8, 2005
- 56
We just put in a 480/277V Y generator feeding a 480V Delta switchboard. During the inspection, we discovered the contractor had grounded the neutral in the generator with 3/0 (same size as the NEC-specced ground wire- looks comically small next to the line conductors). In speaking to the Caterpillar reps on-site, we found out the same N-G connection was also made internally. There is appx 25' of cabling between this generator and the first OCP in the switchboard.
Our senior technician feels strongly that both N-G jumpers should be removed and the delta left to float ungrounded. He's worried a L-G fault will fry the generator. I don't like that the line voltage could float all over the place during normal operation or that an L-G fault could potentially go unnoticed if one should occur. Our lead electrician agreed with me, which is why he wired it up that way.
What's best practice here? Any other pros/cons for either option?
Our senior technician feels strongly that both N-G jumpers should be removed and the delta left to float ungrounded. He's worried a L-G fault will fry the generator. I don't like that the line voltage could float all over the place during normal operation or that an L-G fault could potentially go unnoticed if one should occur. Our lead electrician agreed with me, which is why he wired it up that way.
What's best practice here? Any other pros/cons for either option?