Are shared neutrals allowed in USA in 2021?

[nyDIYelectric1]

Planning a layout for new kitchen with (2) two 120‑volt circuits wired with (1) one three‑wire cable connected to a double‑pole circuit breaker. Is this:

A) Allowed
B) Not Allowed

Black powers one circuit
Red powers other circuit
Green neutral serves both
Ground not shown

ps Image doesnt show GFCI which will be used in Kitchen as per code.
pps Does code generally vary in different States

 

[littlespark]

@Megawatt another one for you.

we wouldn’t do it in uk. I suppose the same is said for US. The neutral is carrying the load being used by both circuits.
Someone in the future works on the first outlet... isolates it’s breaker and tests it. No power, and starts removing wires. The neutral is also carrying the load from the other circuit, so when they separate the neutral joint, bang flash.

of course, I’m simplifying things... and I suppose that’s why you have wire nuts in the back of the boxes... so you can disconnect the outlet without separating the return path.

 

[Deleted account]

edit: took another look at above and realised what you mean. Agree with above. Megawatt can answer

 

[Mike Johnson]

Pretty picture, but looks a very complicated way of achieving a circuit, aren't straight forward Radials allowed in the US?

 

[DJAndy]

View attachment 65039


Black powers one circuit
Red powers other circuit
Green neutral serves both
Ground not shown

Must be my eyes, but I'm sure the legend for this drawing should be
Black = L1
Red = L2
White = N
green = ground

 

[pc1966]

we wouldn’t do it in uk. I suppose the same is said for US. The neutral is carrying the load being used by both circuits.

But here it appears to be a linked double-pole breaker, in that respect not really any different from a typical three-phase system here where it would be allowed to have single phase loads off it to the common neutral (e.g. lights in factory to reduce strobing).

Had it been separate breakers then a definite NO, as for our "shared neutral" prohibition.

But as you said, one for @Megawatt

 

[James]

But here it appears to be a linked double-pole breaker, in that respect not really any different from a typical three-phase system here where it would be allowed to have single phase loads off it to the common neutral (e.g. lights in factory to reduce strobing).

Had it been separate breakers then a definite NO, as for our "shared neutral" prohibition.

But as you said, one for @Megawatt

Agree with this, in the uk we would consider this to be a single circuit although it is multi phase.
The key is the fact it is fed from one circuit breaker, not 2 single pole breakers.

However, it would not be my preferred method of installation for the following reasons.

A fault or overload on 1 set of outlets will trip the power off to both sets.

It would be easy to miss in the future and replace 2 pole breaker with 2 single pole breakers, this would lead to the possibility of a live N when circuit is being worked on and believed to be isolated.

One of the American experts will be better at advising on wiring codes but, in my opinion, the risks are greater than any cost saving or other reward.

 

[Megawatt]

View attachment 65039
Planning a layout for new kitchen with (2) two 120‑volt circuits wired with (1) one three‑wire cable connected to a double‑pole circuit breaker. Is this:

A) Allowed
B) Not Allowed

Black powers one circuit
Red powers other circuit
Green neutral serves both
Ground not shown

ps Image doesnt show GFCI which will be used in Kitchen as per code.
pps Does code generally vary in different States

First off you are not allowed to share neutrals period. And you didn’t just say the GREEN serves both the neutral and the equipment ground. That is so wrong

 

[Megawatt]

Must be my eyes, but I'm sure the legend for this drawing should be
Black = L1
Red = L2
White = N
green = ground

As far as the states being different is because every particular state works out of different editions of the NEC. There are states are still working out of the 2014 edition of the NEC. I don’t get it but your state has adopted the 2020 edition of the NEC and so has my state.

 

[norcal]

With AFCI's being required for almost all residential 120V circuits, it makes it very hard, expensive, and sometimes impossible to use multiwire circuits, & some circuits like kitchen small appliance branch circuits also required to have GFCI protection too, 2 pole AFCI's & GFCI's are not as common, although the 2020 NEC that has been adopted by 9 States, at this writing, is now requiring GFCI's for ranges, dryers, A/C condensing units, too now.