So I am installing a 100A subpanel in the garage to handle a plethora
of power equipment including a couple of welders and a plasma cutter.
This will be #4 copper 4-conductor cable run from the main panel in
the basement (approx 40 foot run).
I have laid out my plan for outlet locations and wire routes, as well
as lighting fixtures, but I am running into a question that is
difficult to get an answer for. If anyone can help, I would appreciate
I wish to install a surface mount subpanel on the wall that separates
my attached garage from my house. I know that it is important to
maintain the integrity of this 'modified 1-hr firewall'. That being
said, my house seems to be a little unique in a couple of respects so
I want to throw this out there to anyone who might have some insight.
The wall separating my garage from my house is, as far as I know, up
to code (with the exception of a rather large hole the previous
homeowners drilled in it for a dryer vent-- which I am planning on
repairing). My basement wall (standard concrete block foundation)
makes up the lower half of this wall... To better explain, the wall
that separates my house from my garage is concrete block up to waist
level, and up-to-code 1-hr modified firewall from waist level on up to
I have pored over the NEC handbook and can not find any reference to
whether or not what I want to do is 'legal' and I want to have some
guidance before I submit my plans to the electrical inspector. The
only reference to any of this I found was in building code, and it was
vague at best (subpanels shall not penetrate 1hr wall). So, now that
you know the background info, here are my string of questions:
1. Is it 'up-to-code' to install a surface mount subpanel on the wall
separating my attached garage from my house?
2. Knowing that it is not allowed to penetrate the firewall itself, is
it up to code to run the feeder cable for the panel through the
waist-level concrete block wall, or is that also considered part of
the modified 1hr wall?
3. If 1 and 2 are OK, is it ok to run the feeder cable up along the
side and then through the top of the surface mounted box to attach to
the main lugs?
4. If I am going down the wrong track completely, can someone please
tell me a best-practices method for running feeder cable through or
around a firewall from a basement to a garage?
Any help or insight anyone can provide would be greatly appreciated.