temp power grounding

[QA/QC Pass]

we have an old MCC (Zinsco) installed in the 1970's, which has no ground buss its 480 3 phase 3 wire, the feeders include the ground wire from the source which is bonded to the frame and then back to the conduit and thats it. we ran an SOW cord for temp power and grounded the ground wire to the frame at the top of the MCC. ? is this acceptable or should we extend the ground to the ground wire coming in with the feeders.

 

[pete m.]

For the EGC attaching to the frame should be acceptable.

Pete