Service Equipment - Grounded Conductor Termination

[Shoe]

For service equipment (article 250), where the neutral-to-ground bond exists, it's not uncommon to land ground electrode conductors, equipment grounds and grounded (neutral) conductors onto the neutral bus in the switchboard.

However, can you land the grounded (neutral) conductors onto the ground bus, which is electrically connected through the bonding jumper to the neutral bus? I'm thinking "no" due to NEC 110.5 but I'd like to hear others thoughts. Thanks

 

[electrofelon]

I agree no. See 200.2(B)

 

[Dennis Alwon]

I also agree--No

 

[Shoe]

Thanks for the replies.

 

[infinity]

However, can you land the grounded (neutral) conductors onto the ground bus, which is electrically connected through the bonding jumper to the neutral bus? I'm thinking "no" due to NEC 110.5 but I'd like to hear others thoughts. Thanks

Also typically the MBJ is much smaller than the neutral and is not designed to carry all of the neutral current.

 

[ptonsparky]

FWIW, I’ve seen the connection at the MBJ, or green screw, fail. Someone had installed a sub, improperly Installed a MBJ and then mixed the neutrals and EGs as you described. Classic ‘open neutral‘ when the bond failed.

 

[don_resqcapt19]

Assuming the main bonding jumper is of the wire type and at least as large as the service neutral conductor, I don't see an issue.

 

[TheGingerElectrician]

Assuming the main bonding jumper is of the wire type and at least as large as the service neutral conductor, I don't see an issue.

Are you meaning that the main bonding jumper is of the wire type and goes between the neutral bar and the ground bar? I wouldn't think it would be code for all the neutral connections to count on the one #10 screw that usually grounds the neutral bar to the panel housing as a lot of panels are. However some have the wire type jumper between the neutral bar and the ground bar built in and then just a #10 bonding screw on the neutral bar that bonds it to the panel. I don't see an issue with putting neutrals on the ground bar in this case but not the other way around. NEC is just a minimum standard anyhow for the guys reading above. You can always make it better and keep them separated as long as your MBJ is in place.

 

[jaggedben]

It seems to me that in the generic case if you land the service neutral on a terminal bar then that bar becomes the neutral bar. Thus it is begging the question to call that bar the ground bar. However if you have listed equipment with instructions that describe a particular terminal bar to be used to tue neutral and another for the EGCs then it would violate 110.3 (B) to switch their purposes.

 

[LarryFine]

However some have the wire type jumper between the neutral bar and the ground bar built in and then just a #10 bonding screw on the neutral bar that bonds it to the panel. I don't see an issue with putting neutrals on the ground bar in this case but not the other way around.

Not sure if you're saying what you're saying, but all neutrals must land on a bus that the source neutral lands on, unless a full-size conductor jumps to an added neutral bus. Also, the grounding electrodes must land on this bus.

Only short-duration fault currents may pass through either metallic enclosures or bonding jumpers. The bonding screw or little jumper makes sure the enclosure, and any EGCs, are bonded to the neutral, but not for neutral current.

 

[TheGingerElectrician]

Not sure if you're saying what you're saying, but all neutrals must land on a bus that the source neutral lands on, unless a full-size conductor jumps to an added neutral bus. Also, the grounding electrodes must land on this bus.

Only short-duration fault currents may pass through either metallic enclosures or bonding jumpers. The bonding screw or little jumper makes sure the enclosure, and any EGCs, are bonded to the neutral, but not for neutral current.

Yes, this is exactly what I was getting at. Well said.

 

[jared albrecht]

wondering if it is acceptable to connect the equipment grounding conductor to a lug that is anchored to the panel can and the ground bar be located elsewhere in the panel but the ground bar is connected directly to the can.

 

[texie]

wondering if it is acceptable to connect the equipment grounding conductor to a lug that is anchored to the panel can and the ground bar be located elsewhere in the panel but the ground bar is connected directly to the can.

Yes. While this has always been permitted, language was added to the 2020 NEC as 250.109 to make this clear.

 

[darkenergy]

2020,2017 NEC 250.24 (A)(4) read it and read it until you understand. or i didn't. wire size could be viewed as another story.
250.28

 

[LarryFine]

wondering if it is acceptable to connect the equipment grounding conductor to a lug that is anchored to the panel can and the ground bar be located elsewhere in the panel but the ground bar is connected directly to the can.

Yes, as Texie just said, the enclosure may be part of the grounding pathway, just like conduit may.

Remember, though, that grounding electrode conductor pathways may not include the enclosure.

 

[darkenergy]

I inadvertently posted this just this morning in the wrong thread. Hasty newbie is my rationalization.

A point of clarification if anyone would care to venture one. If the 'grounding electrode conductor' lands on the equipment grounding bus, that is when the appropriately sized wire type jumper is required to the neutral bar. I would still put in the green screw in the neutral bar. Any opinions or statements of fact as far as you know would be much appreciated.

Thank you, Willy

 

[darkenergy]

Yet again, haste makes waste. The original OP asked…

"However, can you land the grounded (neutral) conductors onto the ground bus, which is electrically connected through the bonding jumper to the neutral bus? I'm thinking "no" due to NEC 110.5 but I'd like to hear others thoughts. Thanks"

All I 'saw' was grounding electrode conductor landed on the equipment grounding bar. I believe my interpretations concerning the grounding electrode conductor landed on the equipment grounding bus is correct, and I'm looking for substantiation/opinions one way or the other. However… Multiple references to 200.2 made me look closer at the original poster's question.

the 'highlighted blue commentary' following 200.2 in the 2017 handbook says… "Grounded conductors are required to be connected to a terminal or bus that is specifically intended and identified for connection of grounded or neutral conductors. Because grounded conductors are current carrying, connecting them to a separate equipment grounding terminal or bar (I. E. Directly connected to a metal cabinet or enclosure) results in the enclosure becoming a neutral conductor between the equipment grounding terminal and the point of connection for the grounded conductor. Note that 300.13 does not permit the wiring terminal of the device, such as a receptacle, to be the means of maintaining the continuity of the grounded conductor and a multi-wire branch circuit"… I do not have the 2020 handbook yet, mainly because of the price and the two states I typically work in are still on the 2017 and 2014 code cycle.

I apologize for any nonsensical words/lack of proofreading. I use dictation software. If I had to type this it would take me a month.

Thank you, Willy

Any help finding the article where specifically states something to the effect of the opening line of the commentary…
"Grounded conductors are required to be connected to a terminal or bus that is specifically intended and identified for connection of grounded or neutral conductors.… Would be much appreciated.