Bonding For Transformer and Rigid 90's

[wawireguy]

I was wondering if have to treat a transformer as a service and bond the conduit to it with bonding bushings? Transformer is 120/208 with a 480 primary being fed from a distribution panel.

If you have rigid 90's stubbbing up through your floor that are being fed from PVC runs do you need bonding bushings on the conduits connecting to the panel?

If you do need to bond in either of these cases can you run a jumper from your bonding bushing to the can or do you have to loop your EGC through the bushing?

Appreciate the help!

 

[raider1]

There are no special bonding requirements for conduits feeding or comming from a transformer. The standard bonding requirements are all that apply.

Chris

 

[wawireguy]

I recall looking in the NEC before but not seeing anything specific for transformers. Guess I didn't miss that section!

 

[raider1]

I recall looking in the NEC before but not seeing anything specific for transformers. Guess I didn't miss that section!

Nope you didn't miss anything.

I can definitely see why someone might feel that there would be enhanced bonding requirements for the secondary of a transformer.

Chris

 

[wawireguy]

How about this one guys. What if you bring the GEC to the transformer in your metallic conduit? I know if you brought the GEC into your service in metallic conduit you would have to bond both ends with bonding bushings, well at least if you ran it up the side of the building from say a couple of ground rods you would. I know I need to look this up but I got fish to catch : )

 

[Flex]

When i run my building steel bond in conduit for a transformer, I bond both ends.

 

[augie47]

250.64(E) refers to bonding enclosures for bonding electrode conductors.
It does not specifically limit the requirement to services, so I would say the rule holds true for GEC on SDS also..

 

[wawireguy]

Hmm, just read 250.64(E) and it needs to be re-written for electricians. Luckily I have the hand book and it has a picture. Still wish I could interpret the engineer speak or whatever it is they wrote for that section.

Looks like you can use jumpers from your bushings instead of looping the GEC through the bushings.

 

[raider1]

Looks like you can use jumpers from your bushings instead of looping the GEC through the bushings.

Yes, you can use a bonding jumper from the bonding busing to the GEC if you want provided that the jumpers are sized the same as the GEC.

Chris