transformer grounding

[Don.Harker]

I am currently installing transformers to power new presses. these transformers are 75KVA delta 3PH 480v primary / 240 volt secondary with a neutral tap for 120v capability on the two corner taps. I am using the 120v capability for aux. machine outlets, and the transformers are large enough to handle the 120v load as well as the machine load. do I need to bond the neutral lug to the ground lug on the transformer frame with a ground wire? Also would it be wise to drive a ground rod (electrode) at the transformer site and connect it to the ground lug?

 

[texie]

Yes, the neutral will need to be bonded. But you need to realize that there is more to this than just putting a bonding jumper on. You need to have a proper GE system, overcurrent protection, etc.

 

[Don.Harker]

I have overcurrent protection on the 120v wires (fuses) the service for the building has a good grounding electrode system at the main service entrance (rods,water pipe and beams all as GE system. should I install a gr. rod at the transformer location also or will this cause the feeder ground to carry a small bit of voltage?

 

[augie47]

You really need to review 250.30 and follow that for your transformer grounding.
The piece-meal questions might well lead into a problem.

 

[Don.Harker]

I read 250.30 and 450.5 which made my brain mush thats why i was asking the questions.