2/3 rating

[griffelectric]

can you use 2/3 romex for a 125amp sub panel residential service even though 2/3 in the ulgy refrence book is rated at 95amps 140f for uf and mb wire insulation?

 

[jumper]

can you use 2/3 romex for a 125amp sub panel residential service even though 2/3 in the ulgy refrence book is rated at 95amps 140f for uf and mb wire insulation?

No. The next standard size breaker or fuse is 100A.

 

[infinity]

You could use MC cable.

 

[kwired]

The problem is NM cable must be treated as 60C conductors, regardless of what the actual insulation is rated for. If this were any other modern wiring method the answer would be yes as it would be able to be used at 75C ampacity rating.

 

[jumper]

The problem is NM cable must be treated as 60C conductors, regardless of what the actual insulation is rated for. If this were any other modern wiring method the answer would be yes as it would be able to be used at 75C ampacity rating.

Another problem is that the largest size NM-B made is #6.

 

[infinity]

Another problem is that the largest size NM-B made is #6.

I think that meant that NM cable is manufactured up on #2.

334.104 Conductors. The 600-volt insulated conductors shall be sizes 14 AWG through 2 AWG copper conductors or sizes 12 AWG through 2 AWG aluminum or copper-clad aluminum conductors. The communications conductors shall comply with Part V of Article 800

 

[jumper]

I think that meant that NM cable is manufactured up on #2.

It could be made that large I suppose, but that does not mean that it is.

Southwire and Encore both stop at #6.

 

[infinity]

It could be made that large I suppose, but that does not mean that it is.

Southwire and Encore both stop at #6.

For Southwire (and I assume Encore) the #6 limit is for two conductor cables. Southwire it's up to #2 for three conductor cables. The OP mentions 2/3 NM cable.

 

[jumper]

For Southwire (and I assume Encore) the #6 limit is for two conductor cables. Southwire it's up to #2 for three conductor cables. The OP mentions 2/3 NM cable.

Well, shoot I missed that.:slaphead:

Gotta pay more attention.:ashamed1:

Edit: Yep, up to #2.

https://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet6

 

[electrofelon]

IMO large NM is about the worst wiring method. Low ampacity, expensive.....no thanks.

 

[jumper]

IMO large NM is about the worst wiring method. Low ampacity, expensive.....no thanks.

For these sizes I have always switched to SER.

 

[Little Bill]

can you use 2/3 romex for a 125amp sub panel residential service even though 2/3 in the ulgy refrence book is rated at 95amps 140f for uf and mb wire insulation?

No. The next standard size breaker or fuse is 100A.

The OP's question was can you use the #2-3 NM for a 125A subpanel.
I see no problem with feeding a 125A subpanel with #2-3 NM as long as the breaker feeding it is sized properly. The 125A sub could be MB or MLO. If MB, the 125A main breaker would just be a switch.

 

[jumper]

The OP's question was can you use the #2-3 NM for a 125A subpanel.
I see no problem with feeding a 125A subpanel with #2-3 NM as long as the breaker feeding it is sized properly. The 125A sub could be MB or MLO. If MB, the 125A main breaker would just be a switch.

I agree. I was assuming a 125A breaker for the feeder OCPD.

 

[Dennis Alwon]

In the past, I have gotten 2/3 copper nm wg from my supplier but that was years ago. They used to stock it at one time.

 

[1793]

I'm jumping into this late in the day but for a Sub-Panel don't you need: two hots, neutral and ground?

 

[Dennis Alwon]

I'm jumping into this late in the day but for a Sub-Panel don't you need: two hots, neutral and ground?

2/3 nm has 2 hots, neutral and equipment grounding conductor. Just like 12/2 nm has an equipment grounding conductor.

 

[MAC702]

I'm jumping into this late in the day but for a Sub-Panel don't you need: two hots, neutral and ground?

The shorthand didn't say it, but it's actually "2/3 with ground."
In cables like NM and MC, the ground is not counted in the number.
In cords like SO, it is.

12/2 cable and 12/3 cord both contain three wires, counting the EGC.

 

[1793]

The shorthand didn't say it, but it's actually "2/3 with ground."
In cables like NM and MC, the ground is not counted in the number.
In cords like SO, it is.

12/2 cable and 12/3 cord both contain three wires, counting the EGC.

That is where I got tripped up, I'm use to the full description to help me keep it straight between the two types.

Thanks