On Dec 11, 10:41 pm, wrote:
On Tue, 11 Dec 2007 17:48:25 -0800 (PST), Big_Jake



wrote:
On Dec 11, 11:29 am, wrote:
On Tue, 11 Dec 2007 10:58:22 -0600, "S. Barker"

wrote:
ACTUALLY #4 can be run for the 100a sub panel.

cite that, it sure isn't what 310.15(B)(6) says

The Table in 310.15(B)(6) says, for a dwelling, which we are assuming
this is, for a "Service or Feeder", which this sounds like, the rating
in amps for a #4 copper or #2 aluminum shall be 100A. Are you saying
that the problem is that it isn't a service but a subpanel? This
should fall under the definition of "feeder" and I'm sure that my AHJ
and electrician had that in mind when they allowed & ran my feeder,
protected by a 100A breaker, through a piece of 2-2-2-4 Aluminum SE
cable.

If I'm wrong, tell me how.

JK

Read the text above the table. It says "feeder conductors that serve
as the main power feeder to a dwelling unit". That means if this is
the feeder to the main breaker you can use the table. This assumes the
diversity of the total house load. You won't be using everything at
once. That may not be true in a feeder to a sub panel since we don't
know what the sub panel serves.
Don't feel bad. A lot of people get confused by this, even inspectors
who should know better.

Here's a couple more for you - (I don't do this for a living)

According to another table in 310-16, my SE cable would have been ok
for 100 amps if the wire was rated for 90c. and #4 Copper ok for 95
amps, which would can be "rounded up" to the next common breaker size,
no?

JK