Main Bonding Jumper

[SMB]

Is it legal to install a green screw (manufacturer provided) through the neutral bus into the back plate of a service entrance disconnect and not route a physical conductor between the neutral bus and ground bus to make the N-G bond? The ground bus is also connected to the back plate with a screw. Looks like 250.28(B) allows this.

Thanks for any and all responses.

 

[petersonra]

Isn't that the way it is normally done?

 

[raider1]

Very common installation practice. That is the reason that the green screw is included with the disconnect.

Chris

 

[SMB]

Government facilities I have dealt with have required a physical conductor between the two to ensure the bond exists by simply inspecting. Some dont trust the "screw" method....even though it is spelled out in the code.

Thanks for your replies.

 

[Dennis Alwon]

I agree with everyone however I want to make sure of one thing. Are you adding an equipment grounding bar and connecting neutrals to it? In that case the screw is not enough to meet code--I would have to hunt that article down but that may be what the facility people are talking about.

 

[raider1]

I agree with everyone however I want to make sure of one thing. Are you adding an equipment grounding bar and connecting neutrals to it? In that case the screw is not enough to meet code--I would have to hunt that article down but that may be what the facility people are talking about.

Dennis are you referring to 200.2(B)?

Chris

 

[Dennis Alwon]

Dennis are you referring to 200.2(B)?

Chris

Thanks Chris-- yes I was. The OP mentioned a ground buss and neutral buss so that may be the issue.

 

[raider1]

Thanks Chris-- yes I was. The OP mentioned a ground buss and neutral buss so that may be the issue.

OK, I figured that was the section you were referring too.

Chris

 

[SMB]

For clarity, the the screw connects the neutral bus to the back of the box. The ground bus is separate of the neutral bus and is also connected to the box by a screw and connects a driven ground rod. This does not seem to violate 200.2(B) as the grounded conductors on both the supply and load side connect to this neutral bus.

 

[LarryFine]

Government facilities I have dealt with have required a physical conductor between the two to ensure the bond exists by simply inspecting. Some dont trust the "screw" method....even though it is spelled out in the code.

It sounds like they don't trust the enclosure metal being part of the bonding pathway.

 

[raider1]

For clarity, the the screw connects the neutral bus to the back of the box. The ground bus is separate of the neutral bus and is also connected to the box by a screw and connects a driven ground rod. This does not seem to violate 200.2(B) as the grounded conductors on both the supply and load side connect to this neutral bus.

Correct, 200.2(B) would only apply if you were connecting neutral conductors to an equipment grounding bus at the service equipment that relied on the enclosure for continuity of the neutral conductor.

Chris

 

[don_resqcapt19]

For clarity, the the screw connects the neutral bus to the back of the box. The ground bus is separate of the neutral bus and is also connected to the box by a screw and connects a driven ground rod. This does not seem to violate 200.2(B) as the grounded conductors on both the supply and load side connect to this neutral bus.

If the driven ground rod is the service grounding electrode, it is not permitted to connect the the ground bus. It must directly connect to the neutral bus where the main bonding jumper is a screw.

 

[Dennis Alwon]

If the driven ground rod is the service grounding electrode, it is not permitted to connect the the ground bus. It must directly connect to the neutral bus where the main bonding jumper is a screw.

Good catch Don.