When to count a neutral as a conductor

[KWH]

When derating conductor ampacity for a conduit run would there be a situation where you would count the neutral as current carrying if you install a neutral for each hot conductor . I am working on a job where the conduit runs are going to be extremely difficult and trying to eliminate some conduits.

Thanks

 

[roger]

When derating conductor ampacity for a conduit run would there be a situation where you would count the neutral as current carrying if you install a neutral for each hot conductor .
Thanks

In that case (two wire circuits) all grounded conductors must be counted since they carry the same current as their ungrounded counterpart.

Roger

 

[Len]

conduit fill

conduit fill

I will have to check code book but a 2 wire branch has no imbalance. If you run multi wire where you share neutral then neutral carries un balanced load and must be carried.
Don't forget to check ampacities when de rating, sometimes the larger wire needed makes it easier to run more conduits.

 

[KWH]

310.15 4 (a) what is this referring to

310.15 4 (a) what is this referring to

I was taking this as one neutral per ungrounded conductor

 

[roger]

I will have to check code book but a 2 wire branch has no imbalance.

Correct, it is balanced and it carries the same current as the ungrounded conductor.

If you run multi wire where you share neutral then neutral carries un balanced load and must be carried.

The neutral would almost never need to be considered a current carrying conductor in a MWBC.


Roger

 

[roger]

I was taking this as one neutral per ungrounded conductor

So was I.

In a two wire circuit the grounded conductor (neutral) is a CCC.

Roger

 

[roger]

Here's an illustration that may help.

Roger

 

[dicklaxt]

I agree with Roger the Dodger

dick

 

[roger]

I agree with Roger the Dodger

dick

Thanks Dick.

Roger

 

[KWH]

Thanks Roger

Thanks Roger

Balanced versus Unbalanced with one ungrounded and one grounded conductor, what would be a common occurance of unbalanced in this scenario concerning your typical office building.

 

[roger]

Balanced versus Unbalanced with one ungrounded and one grounded conductor, what would be a common occurance of unbalanced in this scenario concerning your typical office building.

You would never have an imbalance in a two wire circuit, a neutral that carries only imbalanced current can only exist in a MWBC.

Here's another illustration of a single phase neutral.

Roger

 

[russ]

While in a three wire circuit of a single phase system the neutral would not be counted.
In a Three wire circuit (two phase's and a grounded conductor) of a three phase four wire wye system that grounded conductor would be counted.
Probably don't have to mention about nonlinear loads of three phase systems as noted in 310.15(B)(4)
There is no mention of counting nonlinear on single phase systems.