Sharing Neutrals and Grounds

[Johnboy2316]

I was recently told by my supervisor that I was required by code to provide a separate ground for each circuit contained in a raceway. I was pullng three 120v 20amp circuits from a panel to their respective destinations. When I argued that I was only required to provide a separate ground when supplying an isolated ground circuit like is required in some hospital settings. He went further to say that sharing Neutrals was no longer allowed either. I was under the impression that you were allowed to share Neutrals on multi wire branch circuits as long as they were grouped with their hots , which were on separate phases and were disconnected at a common location ( tandem trip breaker). Am I wrong? I have recently studied 2020 NEC and I believe he is mistaken. Any input?

 

[infinity]

You are correct he is not. MWBC's are still permitted. In a raceway you may use one EGC sized for the largest branch circuit for all of the circuits within that raceway.

 

[Johnboy2316]

Thank you , I thought maybe I was losing my mind.

 

[winnie]

In some cases design specifications require separate neutrals. But this is not a code requirement.

You are quite correct on the code requirements.

-Jon

 

[tom baker]

Thank you , I thought maybe I was losing my mind.

And thanks for asking. I see a lot of "can't do this or that" from some one who is not up on the latest changes. Or always done it that way

 

[Fred B]

You are correct he is not. MWBC's are still permitted. In a raceway you may use one EGC sized for the largest branch circuit for all of the circuits within that raceway.

You're correct, but One other consideration is if the MWBC was serving an area requiring AFCI protection per 210.12, it would be a design issue not related to code that would prevent use of a MWBC as most AFCI breakers still don't work properly with a shared neutral (tripping). So the supervisor may have instituted a no shared neutral personal policy, but to say it's not allowed (per NEC) is inaccurate.
Additionally if the raceway is metal (EMT, IMC, Rigid) it by itself can be your EGC without having a seperate wire EGC (358.60, 342.60, 344.66). So how would the supervisor explain that use and still want seperate EGC for each circuit?

 

[qcroanoke]

In some cases design specifications require separate neutrals. But this is not a code requirement.

You are quite correct on the code requirements.

-Jon

Check your specifications. 99% of our jobs are private neutrals and an equipment ground per raceway.
But as posted not a code requirement.

 

[Strathead]

I was recently told by my supervisor that I was required by code to provide a separate ground for each circuit contained in a raceway. I was pullng three 120v 20amp circuits from a panel to their respective destinations. When I argued that I was only required to provide a separate ground when supplying an isolated ground circuit like is required in some hospital settings. He went further to say that sharing Neutrals was no longer allowed either. I was under the impression that you were allowed to share Neutrals on multi wire branch circuits as long as they were grouped with their hots , which were on separate phases and were disconnected at a common location ( tandem trip breaker). Am I wrong? I have recently studied 2020 NEC and I believe he is mistaken. Any input?

Even with isolated grounds, I have only seen one specification that required a separate isolated ground for each circuit. Usually, ne is enough.

 

[Rick 0920]

I have done some jobs which require not only a separate neutral but an upsized neutral due to the amount of nonlinear loads on the circuits. Where harmonic currents are present, there could be more current flowing on the neutral than on the ungrounded conductors. But this would be addressed in the specs of the job. Under normal conditions, MWBC's should be accepted if installed in accordance to Art. 210.