NATIONAL ELECTRIC CODE - Proposed changes

[mtnelect]

This addition would prevent crossed grounded conductors from causing "Phantom" tripping on
AFCI/GFCI.

 

[hbiss]

How often do we have grounded conductors from more than one circuit in a box in residential work? Your proposal would require every neutral in a box to be identified with a circuit number regardless of whether there is one or more. Lots of work by people who have no experience with number tags. Further, what happens when circuit numbers get changed if the breakers get rearranged? The only time this is going to be used is once when the boxes are made up and devices are installed. Better to have the boxes made up as the wire is pulled by the same person. That way he knows what cable is what.

-Hal

 

[Hv&Lv]

You need an “is“.
On commercial wiring this is done almost automatically

also, the word you need is “elusive” not allusive.

 

[mtnelect]

This addition would prevent crossed grounded conductors from causing "Phantom" tripping on
AFCI/GFCI.
Correction No. 1

 

[retirede]

IMO, this change does not contribute to safety and doesn’t belong in the code.

 

[letgomywago]

No way it'll be done unless a significant remodel were to happen. The costs to do this on say an outlet change out would be more than desired. Being forced to push afci on those is already making people go to unlicensed handymen to swap outs and only after messing up calling an electrician.

 

[brantmacga]

Yeh, I don’t like it. This is one of those things where you just need to know what you’re doing, and no amount of labeling will fix it.

We use identified (striped) grounded conductors anyway, and that’s becoming more common, as well as a specification on a lot of my projects. I still have guys crossing their wires up sometimes.


Sent from my iPhone using Tapatalk

 

[don_resqcapt19]

What you want to require is covered by 200.4(B) in the code now, just not as restrictive as your proposal. No matter what change would be made, it would not go in 200.6 as that covers how conductors are identified a grounded conductors.

If you want to push for circuit identification, you need to do it in 200.4(B) by deleting the words "cable ties, or similar means" in that section.
For finding the correct neutral for the circuit in the future, I have much more confidence in the grouping of the grounded conductor with the associated ungrounded conductors using a cable tie than I do with a wire tag. Wire tags on old installation often fall off.

 

[texie]

I agree with Don. 200.4 already covers this sufficiently. I actually submitted a proposed change along the lines of 200.4 back in the '90s but it was declined. I smiled when 200.4 language was put in the code a few cycles back.

 

[mtnelect]

Another issue that I am looking into is overcurrent protection of the neutral conductors, which is not required at the present time in the NEC.

 

[don_resqcapt19]

Another issue that I am looking into is overcurrent protection of the neutral conductors, which is not required at the present time in the NEC.

How would you propose to accomplish that? Can you cite real world examples where a code compliant installation has had an issue with excessive current on the grounded conductor? With out such examples, your PI is dead in the water and will be resolved by the CMP.

 

[mtnelect]

How would you propose to accomplish that? Can you cite real world examples where a code compliant installation has had an issue with excessive current on the grounded conductor? With out such examples, your PI is dead in the water and will be resolved by the CMP.

This is another issue that parallels the crossed grounded conductors. On commercial service calls I have also observed discolored conductors on neutral service bars. After checking for loose connections, I have not discovered why.

Because of the electrical relationship between the ungrounded conductors and the neutral conductors in multiwire single-phase and three-phase circuits the possibility of overload does not exist except where the load characteristics results in additive harmonics currents in the neutral conductor.

The increased use of electronic equipment might be responsible for this. Maybe ...

 

[Little Bill]

Another issue that I am looking into is overcurrent protection of the neutral conductors, which is not required at the present time in the NEC.

I think you're looking for a solution to a problem that doesn't exist!

 

[don_resqcapt19]

This is another issue that parallels the crossed grounded conductors. On commercial service calls I have also observed discolored conductors on neutral service bars. After checking for loose connections, I have not discovered why.

Because of the electrical relationship between the ungrounded conductors and the neutral conductors in multiwire single-phase and three-phase circuits the possibility of overload does not exist except where the load characteristics results in additive harmonics currents in the neutral conductor.

The increased use of electronic equipment might be responsible for this. Maybe ...

So how do you propose this could be accomplished? I am not aware of any products that would do this.

I don't think you substantiation would even get a second look from the CMP members.

 

[mtnelect]

So how do you propose this could be accomplished? I am not aware of any products that would do this.

I don't think you substantiation would even get a second look from the CMP members.

Can the neutral load(s) be affected by harmonic loads ?

 

[Hv&Lv]

Can the neutral load(s) be affected by harmonic loads ?

Yes. Overload the neutral.

 

[don_resqcapt19]

Can the neutral load(s) be affected by harmonic loads ?

That is not an answer to my question.

 

[mtnelect]

That is not an answer to my question.

Since it is understood that harmonics are created by solid state equipment and increase the load on the neutral. Then it follows that the size of the neutral should be proportional to the load.
Like you, I don't know how to measure it at this time.

 

[don_resqcapt19]

Since it is understood that harmonics are created by solid state equipment and increase the load on the neutral. Then it follows that the size of the neutral should be proportional to the load.
Like you, I don't know how to measure it at this time.

Then you can't really expect a PI to pass. There has to be some method of mitigating the hazard.
I personally don't see this as a hazard that needs to be mitigated.
If you want to pursue this, I think the first step would be a product standard or outline of investigation for a device that would mitigate the issue.

As far as harmonics, that is not much of an issue any more. Products have been redesigned in a manner such that excessive neutral current is not a real issue. There are other issues from harmonics, but overloaded neutrals are not common.