Double Tapped Neutral on bar in panel board.

[Saturn_Europa]

When did the NEC ban double tapping a neutral under one screw on a panel board neutral bar?



2002 NEC 408.21 is the earliest mention I can find of it.

 

[jaggedben]

It has probably always been effectively prohibited by 110.3(B).

 

[electrofelon]

It has probably always been effectively prohibited by 110.3(B).

I think many/most manufacturers allow two conductors per terminal for smaller sizes on ground bars, do they have a different spec for the neutral bars? Ive never dug into the instructions/listing.....

 

[tom baker]

This has been a UL requirement for a long time, but was added to the NEC as most (including my self) didn't know this. Since in many panels the ground and neutral bars are the same, we often landed two neutrals under one screw, thats OK for EGC but not neutrals

 

[jaggedben]

I think many/most manufacturers allow two conductors per terminal for smaller sizes on ground bars, do they have a different spec for the neutral bars? Ive never dug into the instructions/listing.....

I've seen many panel labels that indicate you can use one terminal for two equipment grounds. I don't think I've ever seen one that indicates you can do it with neutrals.

I think the NEC requirement (now 408.41) might have more to do with not interrupting two circuits when only working on one. But I think that if the OP is looking at an installation with more than one neutral on a terminal, it was probably never compliant.

 

[infinity]

I've seen many panel labels that indicate you can use one terminal for two equipment grounds. I don't think I've ever seen one that indicates you can do it with neutrals.

I think the NEC requirement (now 408.41) might have more to do with not interrupting two circuits when only working on one. But I think that if the OP is looking at an installation with more than one neutral on a terminal, it was probably never compliant.

I agree it was never really complaint but overlooked for decades.

 

[Adamjamma]

it is allowed here in UK but only on ring circuits...

 

[jaggedben]

it is allowed here in UK but only on ring circuits...

That's interesting. I think that's in the same spirit as the NEC rule, which has an exception for parallel conductors of the same circuit.

 

[DBoone]

That's interesting. I think that's in the same spirit as the NEC rule, which has an exception for parallel conductors of the same circuit.

My old boss, home builder, would land the neutral and EGC of a circuit under the same screw

 

[DBoone]

I did not mean to quote Ben

 

[electrofelon]

My old boss, home builder, would land the neutral and EGC of a circuit under the same screw

I see that a lot.

 

[Adamjamma]

That's interesting. I think that's in the same spirit as the NEC rule, which has an exception for parallel conductors of the same circuit.

Reason for it in UK is for testing purposes... the circuits are landed in an order that corresponds to the breakers, and grounds are landed on their bar in same exact way... so when you are testing you can get breaker number, use it for neutrals and for ground wires, and test your continuity, etc, using it.

 

[readydave8]

My old boss, home builder, would land the neutral and EGC of a circuit under the same screw

We used to do that a lot, thought it was a good thing: saving spaces on bar for future circuits, and making it easier to find neutral and ground when troubleshooting circuit

Oh well, quality of installations cannot improve without uncovering of previous mistakes

 

[ptonsparky]

The # of spaces available on a neutral bar was half of what was needed years ago. No one stocked an EG bar. You either doubled up or used a split bolt and tailed out all the EGs with a single wire.