Separate G and N Bars in Main Swbd

[charlie b]

This question came to me from a field office. In the main switchboard and in the first panel downstream of a separately derived system, we will have separate ground and neutral bars, with main/system bonding jumpers connecting the two bars. But I can't find a code reference that forbids simply using one bar for both the green and the white wires. Is there such a requirement? 250.28(B) seems to imply that you can have just one bar, as long as there is a properly identified screw bonding the bar to the panel enclosure.

 

[Hv&Lv]

Seems like there was a discussion along these lines some time back, and I remember thinking there isn’t a requirement. The green and whites are essentially on the same bar anyway with the jumper.

There was a comment made though that made sense to me.. if you put green and white on the same bar and have to separate them later for whatever reason, it could get tricky depending on the lengths of the wires

 

[augie47]

With a bonding jumper between the bars, I see no issue. Often, however, the main bond jumper is connected from the neutral bar to the enclosure. In that event one should not connect neutrals to the grounding bar as you would violate 200.2(B) using the enclosure as a path for neutral current.

 

[oldsparky52]

I was taught that landing grounds on the neutral bar in the enclosure where the neutral is grounded is fine. What I did find out is it is much easier to look for shorts between neutrals and grounds by removing the grounding screw from the neutral bar (then replace after ohming the two bars). This is of course prior to power being turned on.

 

[Dennis Alwon]

Here is the section. Some panelboards have a neutral bar that is bonded to the enclosure and then the ground bar is just connected to the enclosure. In that case you cannot land the neutral on the ground bar.

Many panels have a bar that connects the 2 bars together so it really doesn't matter where you land the neutrals. Some may say it must be on the same bar as the neutral feeder and although we do that as well as separate the neutrals and grounds, it is not a requirement, IMO. When I say separate I mean we put neutrals on one bar and the equipment grounding conductor on the other but there is still a bar between the two.

200.2 General. Grounded conductors shall comply with
200.2(A) and (B).
(A) Insulation. The grounded conductor, if insulated, shall
have insulation that is (1) suitable, other than color, for any
ungrounded conductor of the same circuit for systems of
1000 volts or less, or impedance grounded neutral systems of
over 1000 volts, or (2) rated not less than 600 volts for solidly
grounded neutral systems of over 1000 volts as described in
250.184(A).
(B) Continuity. The continuity of a grounded conductor shall
not depend on a connection to a metallic enclosure, raceway,
or cable armor.

 

[Dennis Alwon]

Here is a ge panel. The bottom bar stays in for a service panel and is removed for a sub panel. This panel is clearly not a main breaker panel but you get the drift

 

[don_resqcapt19]

There is no code issue with landing both neutrals and EGCs on the neutral bar. The biggest thing that triggers the use of two bars is the rule in 408.41 which requires each neutral to be landed in its own terminal. With many places prohibiting the use of multiwire branch circuits, there often will not be enough space on the neutral bar to land the EGCs.

And as Dennis said, if the grounding bar does not have a wire or bus jumper to the neutral bar, neutrals cannot be landed on the grounding terminal bar.

 

[Fred B]

There is no code issue with landing both neutrals and EGCs on the neutral bar. The biggest thing that triggers the use of two bars is the rule in 408.41 which requires each neutral to be landed in its own terminal. With many places prohibiting the use of multiwire branch circuits, there often will not be enough space on the neutral bar to land the EGCs.

And as Dennis said, if the grounding bar does not have a wire or bus jumper to the neutral bar, neutrals cannot be landed on the grounding terminal bar.

Several manufacturers are making what they are calling a "plug-on neutral", these panels seem to have solved the issue of not enough space for neutrals to land by have a neutral termination for every breaker space. In addition it eliminates that coil of pigtail wire for the AFCI/GFCI.