120v between neutral bar & grounding bar in panel

[jeff barnes]

situation:
reading 120v between the neutral bar & grounding bar in 120/208v panel. panel fed from 15kva xfmr via 480v bus duct. the electrician identified a reach-in refrigerator as the source of problem.
in my opinion, there is still a problem as you should have never read a difference of potential if the system was properly grounded in the first place or am i missing something here?

jeff

 

[iwire]

There is a serous problem at the transformer or panel.

In one of those locations a bonding jumper must be installed between XO (neutral) and the equipment grounding conductor.

Along with that jumper a grounding electrode conductor must be installed to one of the permitted electrodes.

Building steel is the first choice usually.

This situation must be corrected, it is a serious deficiency.

250.30(A)(1) Bonding Jumper. A bonding jumper in compliance with 250.28(A) through (D) that is sized for the derived phase conductors shall be used to connect the equipment grounding conductors of the separately derived system to the grounded conductor. Except as permitted by 250.24(A)(3), this connection shall be made at any point on the separately derived system from the source to the first system disconnecting means or overcurrent device, or it shall be made at the source of a separately derived system that has no disconnecting means or overcurrent devices. The point of connection shall be the same as the grounding electrode conductor as required in 250.30(A)(2).

 

[dereckbc]

Re: 120v between neutral bar & grounding bar in panel

situation:
the electrician identified a reach-in refrigerator as the source of problem.
in my opinion, there is still a problem

jeff

You are correct, a big problem. Time to find another electrician giving you that answer. The problem is very simple and easy to correct. For that matter should have never occurred in the first place if the electrician was competent.

 

[jeff barnes]

Re: 120v between neutral bar & grounding bar in panel

[quote="dereckbc"
You are correct, a big problem. Time to find another electrician giving you that answer. The problem is very simple and easy to correct. For that matter should have never occurred in the first place if the electrician was competent.[/quote]

i agree with both of you. the electrician works for the schoolboard here. he actually replaced the transformer thinking it was the problem. i never witnessed the installation but did question the grounding of the transformer which he assures is properly grounded. i did tell his supervisor to hold on the the old transformer as it was still good. i was called into it at the end of the day friday, i think we'll sort it out monday am.

jeff