SER in Thermal Insulation

Status
Not open for further replies.
J

jt700

Member
Location
Waltham,MA
The job is a residential service change for a 120/240 Volt 200 AMP Service. Due to having to relocate the Panel, I'll need to install a 200 AMP meter with a 200 amp main breaker. As a result, I'll be using a copper (Customer wants copper) SER to feed the 200 amp MLO panel.

I'm aware of 310.15(B)(7) for 120/240 Volt services - 200 AMP @ 83% = 166 Amps
My question is the SER located within thermal insulation, where most of it will be located in the insulation.
I believe that article 338.10 (B)(4) states that when SER cable is located within thermal insulation that it should be sized within the 60 degree column of table 310.15(B)(16).

If that's the case, should I be using 4/O CU SER?
 
Yes-- that sucks doesn't it. Sometimes I find it easier to pipe it in pvc then to handle that large a cable.

BTW welcome to the forum
 
Also to consider is the length of the run and what portion of it will be in insulation. If it runs thru an attic it can be atop the insulation so that would not be an issue. Look at 310.15(A)(2). So if you have a 50 foot run and only 5 feet is in insulation then you can still use the 75C column

(2) Selection of Ampacity. Where more than one ampacity
applies for a given circuit length, the lowest value shall be
used.
Exception: Where two different ampacities apply to adjacent
portions of a circuit, the higher ampacity shall be
permitted to be used beyond the point of transition, a distance
equal to 3.0 m (10 ft) or 10 percent of the circui
Click to expand...
 
It's about a 25 foot run, and only about 4 feet of it will not be in the insulation.

I guess it's 4/O CU SER, or pipe then, correct?
 
Status
Not open for further replies.
Top