Grounding and bonding a seperately derived system

[Guyute]

480v line side feeding a step down 480v to 240v transformer. We are in debate on the job site whether or not the transformer or the 240v panel is the location where you bond and derive your new ground for the 240v panel. The transformer has to be bonded ground and nuetral, but the 240v panel is the first means of disconnect in the system. The question is does the nuetral and ground in the 240v panel need to be bonded, and does the new ground coming from a ufer go to the transformer or the 240v panel.

 

[pete m.]

You can install the system bonding jumper at either location but typically not at both. Wherever it is that you bond the neutral that is the location that the grounding electrode conductor will terminate.

250.30(A)(1) through (8)

Pete

 

[Guyute]

This was my interpretation as well.
Thanks for the reply

 

[tom baker]

The grounding electrode conductor connection follows the system bonding jumper. The system bonding jumper can be installed at the source (transformer) or first disconnecting means, but not both. Install the grounding electrode conductor connection where the SBJ is.