doubling neutral wires in ground bar in panel

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First of all, if there are separate grounding and neutral buses, you're using the wrong bus.

Otherwise, unless allowed by the panel maker, he is correct.
 
LarryFine said:
First of all, if there are separate grounding and neutral buses, you're using the wrong bus.

Otherwise, unless allowed by the panel maker, he is correct.
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Ground bar and Neutral bar are joined from the inspector's photo. My instructor told us years ago that as long as the two wires are the same size, it is allowed. But I don't recall an NEC reference. I will check the panel brand when I look at the house today. Thank you.
 
My continuing Ed instructor years ago told us it is allowed only if the two wires are the same gauge. I don't think he referenced the NEC. Most of the older homes all have this, but what puzzles me is that no other home inspector I've been asked to follow has ever said this is a code violation. And I have been asked to address many home inspections. It's a first for me to see this tagged. I guess I could add an extra ground bar but I'd like to know if he is right.
 
I think the bigger issue here is neutral current on a ground bar. I've seen cases in person and on the internet where someone will do a panel change, land the neutrals from stoves and dryers on the ground bar only to have the ground bar eventually spark or over heat where its screwed down. I view it like an undersized EGC- its sized to carry brief fault current, not continuous current.
 
It's a fairly recent change iirc only a few cycles ago>>>>


408.41 Grounded Conductor Terminations. Each grounded
conductor shall terminate within the panelboard in an individ
ual terminal that is not also used for another conductor.
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improbable in older panels .....

~RJ~
 
Stevenfyeager said:
My continuing Ed instructor years ago told us it is allowed only if the two wires are the same gauge. I don't think he referenced the NEC. Most of the older homes all have this, but what puzzles me is that no other home inspector I've been asked to follow has ever said this is a code violation. And I have been asked to address many home inspections. It's a first for me to see this tagged. I guess I could add an extra ground bar but I'd like to know if he is right.
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The CE instructor is incorrect. Although the wording has been in the NEC for the last few code cycles it has been part of the listing of the panelboard for many decades.
 
Stevenfyeager said:
A home inspector says having two #12 neutral wires under one screw on the grounding bar in the panel is not allowed. Is he right? Thanks.
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Just to clarify what others have already posted, if the HI cited the problem in a MBP the grounds and neutrals are landed on the same ground/neutral bar. The reason you don’t land 2 neutrals under the same screw is because the likelihood that the screw can loosen from vibration or expansion/contraction over time is greater than you might think. If that happens it will begin to arc and could cause the insulation to melt and the loads (like lighting) to flicker. Having 2 EGC’s under one screw doesn’t present that specific problem (but may present others). If you’re in a MLP the neutrals and EGC’s are landed on a separate bar but again, the neutrals shouldn’t be terminated under the same screw for the reason cited.

I’ve seen many older panels where a neutral and it’s associated EGC were landed under the same screw because of limited ground bar space. The correct way that it should have been done would have been to land each neutral on its own screw and group thr EGC’s together on a separate bar or lug.
 
goldstar said:
I’ve seen many older panels where a neutral and it’s associated EGC were landed under the same screw because of limited ground bar space. The correct way that it should have been done would have been to land each neutral on its own screw and group thr EGC’s together on a separate bar or lug.
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When you write "group EGC's together", are you referring to twisting together as many as will fit in a given hole in the busbar? I've encountered plenty of those in old panels, and it's a real treat straightening all that out to replace the panel.
 
Craigv said:
When you write "group EGC's together", are you referring to twisting together as many as will fit in a given hole in the busbar? I've encountered plenty of those in old panels, and it's a real treat straightening all that out to replace the panel.
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If there is a “rating” shown on the panel cover as to how many EGC’s can be landed under one screw then that’s what you should go by. If not then “grouping” them together and landing them under a lug is a far better option than doubling them up under one screw.
 
You are permitted to join many EGCs and use a single pigtail, as long as it's as large as the largest joined EGC.
 
goldstar said:
If there is a “rating” shown on the panel cover as to how many EGC’s can be landed under one screw then that’s what you should go by. If not then “grouping” them together and landing them under a lug is a far better option than doubling them up under one screw.
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Agreed. I simply dislike the added and unnecessary complexity caused by twisting egc's together in a panel that could otherwise accommodate individual landing. I've never encountered a full panel that was legally loaded (no removed CTL tabs, etc.) that couldn't accommodate individually landed conductors when the busses are rated for single landing only. I assume it must be a listing requirement or at least good design...
 
goldstar said:
Just to clarify what others have already posted, if the HI cited the problem in a MBP the grounds and neutrals are landed on the same ground/neutral bar. The reason you don’t land 2 neutrals under the same screw is because the likelihood that the screw can loosen from vibration or expansion/contraction over time is greater than you might think. If that happens it will begin to arc and could cause the insulation to melt and the loads (like lighting) to flicker. Having 2 EGC’s under one screw doesn’t present that specific problem (but may present others). If you’re in a MLP the neutrals and EGC’s are landed on a separate bar but again, the neutrals shouldn’t be terminated under the same screw for the reason cited.
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The other reason you do not land two neutrals on one screw is that to work on one circuit neutral you would also interrupt (at least temporarily) the neutral of the other circuit. Similar to the problem with the neutral of an MWBC, in that you would have to open both breakers.

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GoldDigger said:
The other reason you do not land two neutrals on one screw is that to work on one circuit neutral you would also interrupt (at least temporarily) the neutral of the other circuit. Similar to the problem with the neutral of an MWBC, in that you would have to open both breakers.

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That’s correct and a good point. Should the neutral on a MWBC that has been doubled up become loose it will cause irreversible problems.:thumbsup:
 
Our AHJ does not allow twisting ground wires together in a panel, they must each connect to a terminal but can be doubled up if same wire gauge and permitted by panel specs. Individual landing of neutral conductors which i do, is a considered good practice but not enforced...they allow doubling up same as ground wire. I have never seen a panel with enough ground screw terminals, so I routinely add additional ground terminals... I connect the added terminal to existing terminal with a #6 jumper. Of course the danger of sending 240 volts to 120 volt appliances will not exist in future wiring because multi-wire circuits will be prohibited in residential wiring. I consider this good practice and have not shared a residential neutral in 10 years.
 
mlnk said:
Of course the danger of sending 240 volts to 120 volt appliances will not exist in future wiring because multi-wire circuits will be prohibited in residential wiring. I consider this good practice and have not shared a residential neutral in 10 years.
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When is that going to happen? Do you know something I don’t? AFAIK you are required to use a 2-p breaker as it stands right now.
 
mlnk said:
Our AHJ does not allow twisting ground wires together in a panel, they must each connect to a terminal but can be doubled up if same wire gauge and permitted by panel specs. Individual landing of neutral conductors which i do, is a considered good practice but not enforced...they allow doubling up same as ground wire. I have never seen a panel with enough ground screw terminals, so I routinely add additional ground terminals... I connect the added terminal to existing terminal with a #6 jumper. Of course the danger of sending 240 volts to 120 volt appliances will not exist in future wiring because multi-wire circuits will be prohibited in residential wiring. I consider this good practice and have not shared a residential neutral in 10 years.
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Where are you getting this?
Yeah, its inconvenient to have a 2-P breaker and have to turn off both circuits just to work on one but in residential that's not too bad. It's often a time & material savings and safe if done correctly. I've never heard anywhere that it will be prohibited in the future.
 
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