methods of grounding transformers

[sparkmantoo]

here is one for everyone. you have a 480v feeding a 120/208v 4w transformer. we had a discussion on how to install a gec and the bonding jumper. one individual said to go from building steel to XO then to the ground bar in the panel, which is the first means of disconnect, in one continuous loop. then go from the frame of the xfrmr to XO along with the egc from the primary circuit. some thing seems odd about this. imo i think that the gec should be just a one wire connection from XO to steel. the bonding wire should go from the can,along with the equipment ground of the xfrmr to XO, then to the ground bar in the panel. would it matter as to how these wires are terminated even though the come to the same point of termination.

 

[dereckbc]

Re: methods of grounding transformers

The GEC has to originate per 250.30(A) (4). This may or may not be building steel.

The other end of the GEC can terminate to either the Xo of the transformer, or the grounded circuit bus (neutral) at the first disconnect means per 250.30(A) (2).

The bonding jumper has to originate to the same point as the GEC on the grounded conductor circuit (neutral) per 250.30(A) (1).

The other end of the bonding jumper can terminate to the transformer can, disconnect enclosure, or ground bus in either the transformer can, or disconnect enclosure.

[ November 11, 2003, 10:08 PM: Message edited by: dereckbc ]