A typical service

[Dr Mantis Toboggan]

When doing a typical service, say a 200A upgrade, and upgrading all the grounding, let's say that you have a water pipe and a pair of ground rods.

You decide to use a separate ground bar in this main panel for whatever reason, the neutral bar will have the bonding screw installed, of course.

Where do you land the #4 from the water pipe and the #6 from the ground rods? The neutral bar or the ground bar? In the end, it would be basically the same thing. But I am wondering where the code stands on this.

 

[480sparky]

The NEC doesn't state a preference.

 

[RUWired]

Article 250.24(A)4 requires you to use the neutral bar in this case because your only using the screw as the main bonding jumper. If you use a wire sized correctly as the main bonding jumper, then you could use either the neutral bar or the new ground bar..

 

[augie47]

I respectfully disagree.
I see nothing in 250.24 that allows you to connect to anything but the neutral buss or some point ahead of the neutral buss.
(1) General. The grounding electrode conductor 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.

To connect to the equipment grounding bar (if separate from the neutral bar) adds to the current path

 

[infinity]

Article 250.24(A)4 requires you to use the neutral bar in this case because your only using the screw as the main bonding jumper. If you use a wire sized correctly as the main bonding jumper, then you could use either the neutral bar or the new ground bar..

I agree, the screw being the key ingredient.

 

[ActionDave]

I respectfully disagree.
I see nothing in 250.24 that allows you to connect to anything but the neutral buss or some point ahead of the neutral buss.
(1) General. The grounding electrode conductor 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.

To connect to the equipment grounding bar (if separate from the neutral bar) adds to the current path

I agree. Respecfully of course.

 

[ronaldrc]

I always thought the bonding screw was just to bond the panel can to the neutral/ground bar.

I would not think a #10 screw would be a large enough bonding jumper between the neutral
and grounding bar in this case,I would assume you would need the regular sized bonding jumper.

All the graphic illustrations in the NEC show the neutral going to the neutral bar when it shows a
separate ground and neutral bar.

 

[infinity]

I'm lost, the neutral is bonded to the enclosure with a screw. The GEC terminates on the EGC bus connected directly to the enclosure and not the neutral bus, how is this correct? The GEC is not terminated between the load end of the service drop and the neutral bus as required in 250.24(A)(1). Maybe I'm missing something.

240.24(A)(4) Main Bonding Jumper as Wire or Busbar. Where the
main bonding jumper specified in 250.28 is a wire or bus-
bar and is installed from the grounded conductor terminal
bar or bus to the equipment grounding terminal bar or bus
in the service equipment, the grounding electrode conduc-
tor shall be permitted to be connected to the equipment
grounding terminal, bar, or bus to which the main bonding
jumper is connected.

250.24(A)(1) General. The grounding electrode conductor connec-
tion 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.

 

[augie47]

I'm lost, the neutral is bonded to the enclosure with a screw. The GEC terminates on the EGC bus connected directly to the enclosure and not the neutral bus, how is this correct? The GEC is not terminated between the load end of the service drop and the neutral bus as required in 250.24(A)(1). Maybe I'm missing something.

My understanding is that if the neutral bonding jumper is a screw then you are depending on the metallic enclosure to conduct the GEC current if the GEC is connected to the separate equipment grounding bar.
If the GEC connects to the neutral buss be (A)(1) or to a equipment grounding buss which is linked to the neutral by a busbar or wire per (A)(4) then you are not depending on sheet metal as your conductor.

 

[ronaldrc]

Please accept my apology in advance if anyone takes this personal
I am not trying to belittle anyone.

But in order for the the main breaker to operate and clear a large AIC
fault the path back to the neutral would be this neutral bonding screw.
If you don't use a bonding jumper between the neutral Bar and grounding bar.

And according to the NEC this would not be large enough as I said above.

Ronald

 

[fmtjfw]

I always thought the bonding screw was just to bond the panel can to the neutral/ground bar.

I would not think a #10 screw would be a large enough bonding jumper between the neutral
and grounding bar in this case,I would assume you would need the regular sized bonding jumper.

All the graphic illustrations in the NEC show the neutral going to the neutral bar when it shows a
separate ground and neutral bar.

You must be thinking of the NEC handbook. The Code itself has no such illustrations.

 

[ronaldrc]

You must be thinking of the NEC handbook. The Code itself has no such illustrations.

Okay my mistake

I meant the NEC handbook,Oh that's my 2002 NEC Handbook
might have change those graphics by now.

Thanks :Ronald

 

[infinity]

My understanding is that if the neutral bonding jumper is a screw then you are depending on the metallic enclosure to conduct the GEC current if the GEC is connected to the separate equipment grounding bar.
If the GEC connects to the neutral buss be (A)(1) or to a equipment grounding buss which is linked to the neutral by a busbar or wire per (A)(4) then you are not depending on sheet metal as your conductor.

Augie aren't we saying the same thing? That's why I said that I was confused.

 

[Dr Mantis Toboggan]

So if the GEC's have to be landed on the neutral bar and not rely on the screw as a MBJ, what about the following situation:

This is the wiring diagram for a Generac SE rated ATS. The diagram shows the GEC's landed on the ground bar. The neutral bar has a screw thru it to bond it to the enclosure. Even if I wanted to land the GEC's on the neutral bar, there aren't enough lugs. I have seen many pictures of this ATS wired up and all of them had the GEC landed on the neutral bar like the diagram says to do, and I assume they all passed inspection.

So in this case, do you follow what the manufacturer says (GEC's on ground bar) or what the code says (GEC's on neutral bar)?

 

[infinity]

So if the GEC's have to be landed on the neutral bar and not rely on the screw as a MBJ, what about the following situation:

This is the wiring diagram for a Generac SE rated ATS. The diagram shows the GEC's landed on the ground bar. The neutral bar has a screw thru it to bond it to the enclosure. Even if I wanted to land the GEC's on the neutral bar, there aren't enough lugs. I have seen many pictures of this ATS wired up and all of them had the GEC landed on the neutral bar like the diagram says to do, and I assume they all passed inspection.

So in this case, do you follow what the manufacturer says (GEC's on ground bar) or what the code says (GEC's on neutral bar)?

The note says that a bonding jumper has been factory installed in the ATS. Do you know for sure that it's a screw?

 

[augie47]

I have seen the ATS in question and my recollection is that it is only a screw for bonding.
It has been a non-issue for me as our GECs are connected in the meter base per POCOs request.

 

[George Stolz]

When the factory disagrees with code, code wins, IMO.

Alternately, you could remove the screw and install a wire instead.

 

[augie47]

My approach would be that if you looked at the ATS diagram as a "requirement", feel free to install that "supplemental" grounding electrode. The service would still need a GEC connected according to the NEC

 

[Dr Mantis Toboggan]

My approach would be that if you looked at the ATS diagram as a "requirement", feel free to install that "supplemental" grounding electrode. The service would still need a GEC connected according to the NEC

I'm sorry, I never mentioned it, but that ATS will become the servie disconnect.

George Stolz- Running a #4 from the ground bar to the neutral bar would be pretty easy, I never thought of that. Honestly, I don't think it's going to be a problem, just wondering the right way.

augie47- The PoCo wants the meter base bonded, not by the GEC but a separate EGC run in parallel with the neutral out of the meter pan. But even if I was to run the GEC through the meter pan first, the MBJ is still required to be in the service disconnect, so would it matter if the GEC went into the meter as well?

 

[ronaldrc]

So if the GEC's have to be landed on the neutral bar and not rely on the screw as a MBJ, what about the following situation:

This is the wiring diagram for a Generac SE rated ATS. The diagram shows the GEC's landed on the ground bar. The neutral bar has a screw thru it to bond it to the enclosure. Even if I wanted to land the GEC's on the neutral bar, there aren't enough lugs. I have seen many pictures of this ATS wired up and all of them had the GEC landed on the neutral bar like the diagram says to do, and I assume they all passed inspection.

So in this case, do you follow what the manufacturer says (GEC's on ground bar) or what the code says (GEC's on neutral bar)?

[/QUOTE]


In this case this ATS is the main and if the instructions say it is Okay to land your Grounding electrode conductor on that grounding bar, then I would assume in this case since it is a approved ATS switch gear that bonding screw
in this panel is sufficient enough to meet NEC. Requirements.

But it has always been my understanding the green bonding screw in the Panels that supply it,
the regular General Electric, Siemens over the counter panels is meant for only bonding the metal panel enclosure only and not the main bonding jumper..

This is the reason when you see a graphic example of using bonding bushings in the main switch gear you will see the jumpers leaving the bushings and all landing on the neutral bar. And we all know the Neutral bar is solid bonded to the panel enclosure.

Ronald