sharing neutrals

[ronball]

how many circuits are allowed to share the same neutral. I thought I had saw
something on cutting down amounts.

 

[ceb58]

how many circuits are allowed to share the same neutral. I thought I had saw
something on cutting down amounts.

If you are refering to a MWBC then it would be 2 for 1ph 1 on A phase 1 on B phase. For three phase it would be 3 1-A 1-B 1-C

 

[raider1]

Typically in a 3 phase system you would have 3 circuits share a neutral and in a single phase system you would have 2 circuits share a neutral, although the NEC does not specifically limit the amount of circuits that share a neutral provided that the neutral is properly sized.

A new section in the NEC does require that when you have a multiwire branch circuit (Circuits that share a neutral) that the circuit have a means to simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates. (See 210.4(B))

Chris

 

[infinity]

This had been debated before. For circuits under Article 225 you could run a common neutral for more than three circuits. Look at 225.7(B). Does this applies to other circuits is where the debate begins.

 

[nyhockey]

how many circuits are allowed to share the same neutral. I thought I had saw
something on cutting down amounts.

In the 2008 NEC we are still aloud to share neutrals but it is becoming more of a question weather it is worth it 210.4(B)

 

[jaylectricity]

I installed a 200 amp, 40 circuit panel. They all share the same neutral. :grin:

 

[mivey]

i installed a 200 amp, 40 circuit panel. They all share the same neutral. :grin:

lol .:grin:

 

[btharmy]

Typically in a 3 phase system you would have 3 circuits share a neutral and in a single phase system you would have 2 circuits share a neutral, although the NEC does not specifically limit the amount of circuits that share a neutral provided that the neutral is properly sized.

A new section in the NEC does require that when you have a multiwire branch circuit (Circuits that share a neutral) that the circuit have a means to simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates. (See 210.4(B))

Chris

Based on the availability of (or lack of ) 4 or more pole breakers, the second point of this thread may tend to limit the first part.

 

[raider1]

Based on the availability of (or lack of ) 4 or more pole breakers, the second point of this thread may tend to limit the first part.

210.4(B) does not require a common trip breaker, you can use identified handle ties, but I agree the chance that you will find an identified handle tie for 4 or more single pole breakers would be slim to none.

Chris

 

[LarryFine]

... I agree the chance that you will find an identified handle tie for 4 or more single pole breakers would be slim to none.

You could always pry one off of a 3p shunt-trip that has a fourth case and handle.

 

[gndrod]

A safety consideration for not using shared neutral circuits in residential is that a common tie cannot be reset until the single trip fault is found and repaired. This could be detrimental if the related CB's have lighting and utilization on the common shared circuits, potentially leaving the occupants in the dark in certain circumstances. rbj

 

[LarryFine]

A safety consideration for not using shared neutral circuits in residential is that a common tie cannot be reset until the single trip fault is found and repaired. This could be detrimental if the related CB's have lighting and utilization on the common shared circuits, potentially leaving the occupants in the dark in certain circumstances. rbj

Whether for safety or just inconvenience, that's one of the reasons I prefer separate receptacle and lighting circuits in most rooms.