# Minimum size neutral for service....

#### xformer

##### Senior Member
What is the minimum size Cu neutral required for a 100 amp service, being fed with #4 Cu conductors?

#### don_resqcapt19

##### Moderator
Staff member
Without seeing the load calculations, you cannot find out the minimum size of the grounded conductor. It will either be sized per 220.61 or 250.24(C)(1).

#### xformer

##### Senior Member
My thoughts exactly Don.. thanks...

#### Volta

##### Senior Member
As Don said, we cannot know what the minimum for the particular situation in question with the information given.

But, with that said, the minimum per his reference of 250.24(C) > 250.66 shows that it won't be smaller than #8 copper.

Of course some people might claim that 250.24(C)(1) would not apply to SE cable, due to the subsection's title, but I wouldn't even bring that up. :angel:

#### kwired

##### Electron manager
As Don said, we cannot know what the minimum for the particular situation in question with the information given.

But, with that said, the minimum per his reference of 250.24(C) > 250.66 shows that it won't be smaller than #8 copper.

Of course some people might claim that 250.24(C)(1) would not apply to SE cable, due to the subsection's title, but I wouldn't even bring that up. :angel:

As far as SE cable goes, have you ever seen cable with 4 AWG ungrounded conductors that also has less than an 8 AWG grounded conductor?

I would think it may be available, but would have to be custom ordered, and unless you are going to order a large quantity, will probably cost more than whatever is commonly stocked.

#### Volta

##### Senior Member
As far as SE cable goes, have you ever seen cable with 4 AWG ungrounded conductors that also has less than an 8 AWG grounded conductor?

I would think it may be available, but would have to be custom ordered, and unless you are going to order a large quantity, will probably cost more than whatever is commonly stocked.
Nope, you're right, never have. In fact don't see all that much copper SE around here, just occasionally, and only when you shop around. Maybe open wiring on insulators then would be a better example of a method that may technically allow smaller than a #8 neutral with #4 ungrounded conductors for a service, but I don't imagine that is the intent. Nor have I ever looked into it before I brought it up tonight.