I installed a 225 KVA transformer 277-480 / 120-208 volt Y-Y connected.
The primary side is protected with a 400 amp breaker (250%) and the secondary is protected with a 600 Amp breaker at the transformer.
The primary 400 Amp feeder is a parallel 4w 3/0 cu M/C cable with a #4 gnd.
The engineer has directed me to replace the cable with a cable that has a #3 grnd wire to meet the requirements of the minimum equipment ground size for a 400 amp breaker.
My interpertation is that the wire in question is a bonding wire because the conductor is bonded to the neutral conductor at the transformer not at the 400 amp breaker. A bonding conductor is not required to be installed in the raceway where an Equipment grounding conductor needs to be in the jacket/raceway.
If the engineer is correct what are my options short of replacing the cables or changing the 400 amp breaker to a 300 amp breaker?
Any one have any ideas?
The primary side is protected with a 400 amp breaker (250%) and the secondary is protected with a 600 Amp breaker at the transformer.
The primary 400 Amp feeder is a parallel 4w 3/0 cu M/C cable with a #4 gnd.
The engineer has directed me to replace the cable with a cable that has a #3 grnd wire to meet the requirements of the minimum equipment ground size for a 400 amp breaker.
My interpertation is that the wire in question is a bonding wire because the conductor is bonded to the neutral conductor at the transformer not at the 400 amp breaker. A bonding conductor is not required to be installed in the raceway where an Equipment grounding conductor needs to be in the jacket/raceway.
If the engineer is correct what are my options short of replacing the cables or changing the 400 amp breaker to a 300 amp breaker?
Any one have any ideas?
