125 amp Subpanel Conductor Size Confirmation

[7th Kahuna]

I figured this would be an easy search but I found conflicting information. In any case, what I need is simple, I just wanted a second opinion before I spent the money.

My dad and I are setting a new 125 amp sub-panel for our shop. It is fed from a new main panel located in the same structure. The main panel is 200 amp and the cable run is under 35 feet. They are actually about 15 feet apart but stuff got in the way. You know how that goes, best laid plans and such . . .

Because of the windy route, we will be using SE Cable rather than pulling the conductors in a rigid conduit, and our plan is to use copper rather than aluminum conductors.

I believe I want to order 2-2-2-4. Does that sound right to the electricians among us?

A second question while I'm at it. There is a portion of this run that I would like to give extra protection. Can SE cable be run through a short length of rigid (+/- 6 feet) or do the same rules apply as for Romex? In other words, not allowed.

Yes this is being inspected. The installation is in Los Angeles County, CA.

Thank you.

 

[pattenp]

If you are wanting the full 125A then you need 1-1-1-3 Cu @ 130A. The 2-2-2-4 Cu is 115A.

SE can be placed in conduit, so can Romex. If using as a sleeve just make sure the conduit is large enough to freely get the wire through.

 

[wyliesdiesels]

You didnt list the amp rating of the feeding breaker but if youre intending on using a 125a breaker, then #2 cu is too small. #2 cu is rated at 115a. You will need #1.

There is no prohibition on SE type or NM-b(Romex) type cable in conduit indoors.

EDIT: Pattenp posted while i was typing.

 

[7th Kahuna]

Thank you both for the feedback. I guess I am still confused about how to read the chart but I see what column you are in.

I have been told by an inspector, no Romex in conduit. Perhaps the difference is in it being an open ended sleeve?

 

[7th Kahuna]

I was assuming a 125 amp breaker given the future needs are undetermined but I will have to discuss that with my dad. We chose the panel more for the number of breaker positions than for the max amps. I needed space for several 220 volt pairs.

 

[wyliesdiesels]

You are probably looming at the 90* c column.

The ampacities in that column are for derating purposes only.

You cant use it for sizing breakers.

There is no prohibition in the nec on nm or se cable in conduit

The only thing that may be different in your area is local written amendmdnts.

So ask the inspector for an actual code reference.

If there are no local amendments and he cant provide a code reference then he cant enforce that rule.

 

[pattenp]

THE SE can be sized from the 75 deg.C column. But there is a catch. If more that 10% of the total cable length up to a max of 10ft is buried in insulation then SE is to be sized by 60 deg.C which drops the #1 down to 110A.

 

[7th Kahuna]

Thank you both for the more detailed explanation. I really appreciate it.