knoppdude
Senior Member
- Location
- Sacramento,ca
I have a transformer that is being installed for a 5 hp pump motor, and the plant electrician ordered a 120/240-480 step down transformer that is being used as a step up transformer, to boost 240 to 480. The problem with this, is that using the transformer in this fashion allows no place to ground the transformer on the "new" secondary, with the exception of corner grounding it. This is the only way I can see to allow the O/C device to trip on a fault. However, the grounded leg would not cause the breaker to trip, except through the motor single phasing. This would probably cause the O/L device to trip. I have searched through the 2008 NEC for clarification, but the fact is, I think the transformer is simply being used in a way not in compliance with the manufacturers specifications. I am not happy with this situation, but the plant electrician seems ok with it. Does anyone know if there is a code section dealing with this? There is no place to center tap a winding, it is a delta-delta transformer.