I'm planning to install a subpanel on the 2nd floor that is fed from a
main in the basement. I'm guessing it's about a 40' run. The panel
will be 100A or 125A. The reading I've done so far suggested I need
SER type cable for the feeder run. I couldn't find this cable at any
local home store. One store had SER aluminum listed as special order,
but they couldn't get it anyway.
Any idea what the right cable is for this? I also hope this comes as
a sheathed cable, or would it be 4 separate cables?
Not unless I can get some kind of thin flexible conduit. I'll be
running this across the basement (through the floor joists), up the
inside of the wall, into an attic space, along a roof joist and down a
wall stud into the new panel.
On Dec 10, 10:42 pm, firstname.lastname@example.org wrote:
I ran a feeder for an addition on my house, very similar to what you
are talking about. It is SE cable or "Service Entrance" cable, and
not exactly romex, but the same idea. I bought mine around the time
copper was at the all time high, so we went with aluminum. It is
2-2-2-4 cable, with three 2 gauge conductors and one 4 gauge conductor
for the ground. I think it was around $1.50 / foot, from a supply
house. This was for 100 amps. I assume the copper equivalent would
be one gauge smaller, but I don't have my code book in my hands.
My cable is about 1" in diameter, so the copper equivalent would be a
little smaller, but still really substantial. You also want to be
VERY sure that you don't run in where you might shoot a drywall screw
or a nail into it. With 100A going through it, you could have a
really bad day.
On Mon, 10 Dec 2007 18:27:54 -0800 (PST), email@example.com wrote:
You may have to go to a real electrical supply. #1 SER is probably way
out of the "hobby" class that the home stores cater to.
The other question is, are you sure you really need 100a? Are you
using electric strip heat or a tankless water heater?
So #1 SER is what I need?
I'm running a ton of stuff. I'll install 7 20A circuits. I calc the
max simultaneous draw will be in the 70A range. It includes a couple
space heaters, two electric griddles, a heat gun (the latter two for
encaustic painting), computers, lighting, some tools. Part of what's
going on is I'm making up for some homeowner installed way
undersuitable wiring. My entire 2nd floor (about 500 sf) is tied into
1 first floor 20A circuit. So I can barely draw from the existing
wiring for my needs.
On Dec 11, 12:18 am, firstname.lastname@example.org wrote:
I'm not completely up on my code, but apparently there is an exception
which allowed me to have 100A breaker with the 2-2-2-4 Aluminum SE
cable. All the work was down under permit and has been inspected.
On Tue, 11 Dec 2007 07:14:11 -0800 (PST), Big_Jake
You are talking about 310.15(B)(6) but that only applies to the "main
power feeder to a dwelling unit" not feeders to sub panels.
I doubt it would cause a problem in this application since I don't
think he will draw anything near 100a but it is what the code says.
On Dec 11, 11:29 am, email@example.com wrote:
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
If I'm wrong, tell me how.
On Tue, 11 Dec 2007 17:48:25 -0800 (PST), Big_Jake
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.
On Dec 11, 10:41 pm, firstname.lastname@example.org wrote:
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,
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