Can I run #8 CU (UF) wire as a neutral on a 60amp circuit 140ft.?

stanfortyman · Apr 21, 2011, 08:23 AM

It is ABSOLUTELY NOT ok to do this.
1) The #8 neutral may or may not be OK size wise. The loads would determine this.

2) The neutral CANNOT be in a separate conduit or cable from the hots. Your "electrician" friend should have told you this.

sawsall02 · Apr 21, 2011, 09:27 AM

Thanks Stanfortyman,

I have since upgraded to a #6 wire for my neutral, since my original question. My conscience got the better of me. However, in regards to your second point. I do not intend to run them in a separate conduit. The #6-2 and single strand will be wrapped and taped together. Do you still see a problem with this?

stanfortyman · Apr 21, 2011, 11:54 AM

Quote:

Originally Posted by sawsall02

I do not intend to run them in a separate conduit. The #6-2 and single strand will be wrapped and taped together. Do you still see a problem with this?

Yes I do.

I mentioned conduit OR cable.

You CANNOT run two different cables for the same circuit. The neutral MUST be inside the same sheath with the others.

sawsall02 · Apr 21, 2011, 05:32 PM

Quote:

Originally Posted by stanfortyman

Quote:

Originally Posted by sawsall02

I do not intend to run them in a separate conduit. The #6-2 and single strand will be wrapped and taped together. Do you still see a problem with this?

Yes I do.

I mentioned conduit OR cable.

You CANNOT run two different cables for the same circuit. The neutral MUST be inside the same sheath with the others.

Thanks for the advice Stanfortyman.

sawsall02 · Apr 21, 2011, 07:03 PM

Quote:

Originally Posted by stanfortyman

Quote:

Originally Posted by sawsall02

I do not intend to run them in a separate conduit. The #6-2 and single strand will be wrapped and taped together. Do you still see a problem with this?

Yes I do.

I mentioned conduit OR cable.

You CANNOT run two different cables for the same circuit. The neutral MUST be inside the same sheath with the others.

Is this a NEC code? That all wires must be in the same sheath? Curiosity, why would running wires in different sheaths or outer jackets be a problem? Please, educate me.

tkrussell · Apr 22, 2011, 02:55 AM

Stan's advice is coming form this section of the 2008 NEC:

(B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise permitted in accordance with 300.3(B)(1) through (B)(4).

Note it states "trench". My interpretation is if you already have a 2 wire cable in a trench, it will be permissible to lay an additional conductor cable next to this cable.

At each end of this wiring, where it exits the earth and needs to enter buildings, all conductors will need to be inside one conduit.

A neutral can be reduced to be no less than 70% of the circuit rating, I think for this purpose, a #8 will be fine.

sawsall02 · Apr 22, 2011, 06:51 AM

Quote:

Originally Posted by tkrussell

Stan's advice is coming form this section of the 2008 NEC:

(B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise permitted in accordance with 300.3(B)(1) through (B)(4).

Note it states "trench". My interpretation is if you already have a 2 wire cable in a trench, it will be permissible to lay an additional conductor cable next to this cable.

At each end of this wiring, where it exits the earth and needs to enter buildings, all conductors will need to be inside one conduit.

A neutral can be reduced to be no less than 70% of the circuit rating, I think for this purpose, a #8 will be fine.

Now that's what I wanted to hear! Yes, all wires will share the same trench and conduit. Also, I am up-grading to a #6 wire, just to be safe. Wish you would have responded earlier tkrussell. Thank You just the same!

donf · Apr 22, 2011, 09:28 AM

My take on this issue is the same as Stan's. So I'm probably just as incorrect.

I interpret that section of code as specifically telling me that if I have a conduit and I need to pull four individual conductors through the conduit, I'm okay.

If I have to pull a cable through the conduit and it contains the needed four conductors again that's fine.

However, if I pull a three conductor cable and an individual conductor for the same equipment, I am violating code.

The fact that the conduit is carrying both the cable and the individual conductor does not mitigate the requirement that all four of the conductors must be within the same sheath.

The code is specifically telling you that you cannot attach the forth conductor to the outside of the cable sheath that contains the other three.

stanfortyman · Apr 22, 2011, 02:17 PM

Quote:

Originally Posted by sawsall02

Now that's what I wanted to hear!

Of course it is. Most folks do come to sites like this to get only the answers they want.

Sorry, but my interpretation still stands firm (no disrespect to TK).
Yes, it says trench, but it also says cable. It used to be common to use individual UF or USE conductors in a trench. The fact that you have two in one cable and one in the another nullifies this. The word cable along with the word trench, IMO, makes this so.
You cannot simply choose which one works for you. You have to consider the whole thing. If you are running cable (you are) then ALL the conductors for the circuit MUST be in that cable. If you were running individual conductor/cables then that would be different.

I am sure you are going to do what you want with this, but I had to at least explain my professional position.

Can I run #8 CU (UF) wire as a neutral on a 60amp circuit 140ft.?

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