250.24(A)(4) Main Bonding Jumper

[dereckbc]

I have a dispute with one of my contractors about the termination point of the GEC, and want to get some interpretations of 250.25(A)(4).

What I have is 600-amp service disconnect enclosure with 4-wire, 3-phase 208Y/120. There is an insulated neutral bus on one side of the cabinet. The MBJ is a wire from the neutral bus to the cabinet enclosure.

The GEC enters on the other side of the cabinet, and terminates to the enclosure where it enters.

My argument is the GEC must terminate to the insulated neutral bus first, then let the MBJ bond the cabinet.

My contractor insists this meets the intent of 250.24(A)(4). I say it does not because the cabinet does not have a ground bus per say, only the cabinet enclosure.

What is your opinion?

 

[hornetd]

Re: 250.24(A)(4) Main Bonding Jumper

Dereck
The GEC should be terminated to the neutral buss or to the EGC buss. Terminating it to the cabinet is not an option that I can find in the code.

250.24 Grounding Service-Supplied Alternating-Current Systems.
(A) System Grounding Connections. A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)(1) through (A)(5).
(1) General. The connection shall be made at any accessible point from the load end of the service drop or service lateral to and including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.
(4) Main Bonding Jumper as Wire or Busbar. Where the main bonding jumper specified in 250.28 is a wire or busbar and is installed from the neutral bar or bus to the equipment grounding terminal bar or bus in the service equipment, the grounding electrode conductor shall be permitted to be connected to the equipment grounding terminal bar or bus to which the main bonding jumper is connected.

I just don't see the cabinet as the same thing as an Equipment Grounding Conductor buss bar.
--
Tom

[ August 04, 2003, 10:05 PM: Message edited by: hornetd ]

 

[roger]

Re: 250.24(A)(4) Main Bonding Jumper

Tom, I think 250.25 is a typo.

Dereck with what you are explaining I agree he is wrong. I would argue the wording of 250.24(C) and 110.5. If we are going to use the enclosure for a conductor the material used will have to be sized accordingly. If we are not using the enclosure for a conductor, the true conductors will have to terminate on bars.

Roger

 

[dereckbc]

Re: 250.24(A)(4) Main Bonding Jumper

Tom, it is a typo on my part. 250.24(A)(4) is the correct article.

 

[hornetd]

Re: 250.24(A)(4) Main Bonding Jumper

Roger
When I reread the title I figured that out. I edited my answer.
--
Tom

 

[don_resqcapt19]

Re: 250.24(A)(4) Main Bonding Jumper

Dereck,
I agree that the GEC must be connected to the grounded conductor bus as required by 250.24(A)(1). As you pointed out, there is no equipment grounding bar or bus so 250.24(A)(4) does not apply to this installation.
Don