Bonding -Grounding the Neutral

[david]

Re: Bonding -Grounding the Neutral

250.28(A) Material. Main bonding jumpers shall be of copper or other corrosion-resistant material. A main bonding jumper shall be a wire, bus, screw, or similar suitable conductor.

Generally the main bonding jumper is the connection between the service neutral and the equipment ground at the service. The material allowed to bond the grounded conductor to the equipment ground is listed in 250.28(A)

Notice though in 250.24 specifically identifies the bonding jumpers listed in 250.28(A) that are allowed to be used to bond buses together if the grounding electrode conductor and the grounded conductor are separated onto two different bus-bars The bonding screw is not allowed in this application

So again I am saying you are not allowed to attach the grounding electrode conductor to a lug unless there is a main bonding jumper the bonds that lug or additional bus directly to the (Neutral Bus)

 

[stew]

Re: Bonding -Grounding the Neutral

I guess I just dont understand when the neutral buss is properly an permantly bonded to the can the can cant be the means by which the gec is bonded back to the neutral buss. This I guess would mean theat I would have to start my GEC from the first neutral bus then under a lay lug and continue in that manner thru each can and out to the gec rod eh?

[ March 06, 2004, 01:13 PM: Message edited by: stew ]

 

[iwire]

Re: Bonding -Grounding the Neutral

I think these two sections of 250.24 make it clear that the GEC must be connected directly to the neutral bus or conductor or in some cases you may allowed to connect it to the grounding bus.

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.

250.24(A)(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.

Where these requirements are so specific and the lack of another one saying you can lug the GEC to the enclosure I would say that would be a violation.

[ March 06, 2004, 01:38 PM: Message edited by: iwire ]

 

[stew]

Re: Bonding -Grounding the Neutral

I wire I gues I was interpreting section 250.24(A) a bit differently thatn you have or maybe I am misinterpreting it. (a) 1 says the connection shall be made at any accessible point.I totake that to mean that and accesible point would be the can itself adjacent to the buss but I guees thats wrong eh?

 

[iwire]

Re: Bonding -Grounding the Neutral

Stew I think that the part you mention

250.24(A)(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.

Does give the impression that anything between the the service drop and the service disconnect is fair game.

But before the code says that, we have already been told.

250.24(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).

So when the two are put together we get any accessible point to the grounded service conductor

While electrically at the same potential the steel of the enclosure is not the grounded service conductor.

 

[stew]

Re: Bonding -Grounding the Neutral

and neither is the buss to which it is attached. Ithe buss is however on of many accesible points at which to attach eh? I fail to see why the buss is any different then the can wwhen a proper bonding is done in the can.

[ March 06, 2004, 06:47 PM: Message edited by: stew ]

 

[iwire]

Re: Bonding -Grounding the Neutral

Stew I have no real idea why it is considered differently, maybe for reasons of reliability.

Also in many installations there is a constant flow of current on the GEC, maybe the thought is this current would heat the steel of the enclosures.

But the articles specifically call out the grounded conductor or the bus, no mention of the enclosure.

250.24(A)(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.

 

[stew]

Re: Bonding -Grounding the Neutral

OK I give up!!! Except what makes you think the enclosure wont carry any current when its already bonded back to the nuetral?

[ March 07, 2004, 04:29 PM: Message edited by: stew ]