Distribution pnl Neutral/ground bus

[guygroulx]

I'm use to Canadian main distribution panel (residential) and they are different to the US ones in the following manner:
The Canadian ones have a "Ground" bus the only thng that you can connect to this one is the ground wire or bare or green insulated wire. It is connected to the panel box and the grounding rod.
It also has one or two (depending on brand) neutral bus. The neutral bus has a solid bar connecting it to the neutral wire of the service.
Of course, using a ohm meter, the neutral and ground bus are at the same potential or I should say will show continuity on an ohm meter connected between ground and neutral.
Where as in the US both the ground and neutral (bare and white insulated wire) are connected to the same bus.
Question:
What is the difference?
Does the grounding/bounding operate in a different way?
Why the difference?
Thanks
Guy Groulx

[ November 20, 2005, 04:57 PM: Message edited by: guygroulx ]

 

[bphgravity]

Re: Distribution pnl Neutral/ground bus

I'm not following your Ohmmeter statement. If you are reading infinity on the meter, there is no connection between the two points. There is no way then that they are both at the same potential then?

The US system requires one circuit of the service to be grounded. This is what you are calling the neutral. At the service, the service neutral, the enclousre and the GE system is all bonded together. This is why the ground/neutral location is the same in service equipment.

All panelboards after the service are arranged as you describe isolating the neutral for the enclosure and any grounded (bonded) parts.

 

[guygroulx]

Re: Distribution pnl Neutral/ground bus

Sorry Bryan.
I know better. You are correct. I misused the term infinity. I mean that with the panel off (on a Canadian panel....) and an ohm meter connected to the ground bus on one lead and to the neutral bus on the other lead I get continuity..... now that's the term that I meant to use.
Thanks for the correction.
Guy

 

[LarryFine]

Re: Distribution pnl Neutral/ground bus

Guy, what you described is exactly how we wire a panel fed from a main disconnect ahead of (not within) the panel we're discussing. Somewhere in the system you have, the ground and the neutral are interconnected; just not in this panel. Is there an upstream disconnect?

 

[charlie b]

Re: Distribution pnl Neutral/ground bus

Originally posted by guygroulx: Where as in the US both the ground and neutral (bare and white insulated wire) are connected to the same bus.

At the main service point, the ground bus and the neutral bus are bonded to each other. But I suspect that in many instances, particularly in residential applications, there is only one bus with both types of wires connected to it, or there are two buses that are used interchangeably (white and bare wires on the same bus). In theory it would not make a difference, so long as it happens only at the main panel.

 

[LarryFine]

Re: Distribution pnl Neutral/ground bus

Originally posted by charlie b:
In theory it would not make a difference, so long as it happens only at the main panel.

If you don't mind, Charlie, it happens at the main disconnect, whether that's in the main panel or before it.

 

[hurk27]

Re: Distribution pnl Neutral/ground bus

By Guy: The Canadian ones have a "Ground" bus the only thing that you can connect to this one is the ground wire or bare or green insulated wire. It is connected to the panel box and the grounding rod.

The ground rod or grounding electrode conductor (GEC) has to connect to the grounded circuit conductor by a wire or busbar, it can't be a screw that screws the grounding bar to the panel case or the panel case it self. see250.24(A)(4)

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.

[ November 25, 2005, 06:52 PM: Message edited by: hurk27 ]

 

[charlie b]

Re: Distribution pnl Neutral/ground bus

Originally posted by LarryFine:If you don't mind, Charlie, it happens at the main disconnect, whether that's in the main panel or before it.

I don't mind. You're right.

 

[hurk27]

Re: Distribution pnl Neutral/ground bus

Yep Charlie My parents told me that all the time.

 

[LarryFine]

Re: Distribution pnl Neutral/ground bus

Originally posted by hurk27:
Yep Charlie My parents told me that all the time.

I can hear it now...

"Remember, Little Hurk, always look both ways before crossing the street, wait an hour before swimming after eating, always wear clean underwear in case you're in an accident, and only connect your neutral and ground together at the main disconnect!"