Service Equipment - Grounded Conductor Termination

Shoe

Senior Member
Location
USA
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
 

infinity

Moderator
Staff member
Location
New Jersey
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.
 

TheGingerElectrician

Master Electrician Electrical Contractor, TN
Location
Tennessee
Occupation
Electrical Contractor
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

Senior Member
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

Master Electrician Electric Contractor Richmond VA
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

Master Electrician Electrical Contractor, TN
Location
Tennessee
Occupation
Electrical Contractor
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.
 
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