Hi all,

I need an electrical wizard to advise me here. I am installing a new
hot air wood furnace next to an existing electrical furnace. I have run
the 20 amp cable along the basement ceiling ok and now I need to drop
down to the furnace. I want to add a cut-off switch so that I can
isolate the thing in an emergency.

Can I put this switch on the plenum? In a metal box? The other furnace
has a small breaker box on its plenum with 3 breakers inside, so I
can't se why I should not be able to do this. I have used standard
orange 10-gauge romex cable.

Plenum temp is set typically to turn on fan at 170, and will open an
emergency heat dump at 200 in case of a problem.

Thanks!

Dean

no.
"temperature rating of the insulation of the conductor due to the
terminal limitations of 60 degrees centigrade of the terminals used in
the circuits"
60C = 140F

On 25 Jan 2006 21:46:40 -0800, "dean" wrote:

Hi all,

I need an electrical wizard to advise me here. I am installing a new
hot air wood furnace next to an existing electrical furnace. I have run
the 20 amp cable along the basement ceiling ok and now I need to drop
down to the furnace. I want to add a cut-off switch so that I can
isolate the thing in an emergency.

Can I put this switch on the plenum? In a metal box? The other furnace
has a small breaker box on its plenum with 3 breakers inside, so I
can't se why I should not be able to do this. I have used standard
orange 10-gauge romex cable.

Plenum temp is set typically to turn on fan at 170, and will open an
emergency heat dump at 200 in case of a problem.

Thanks!

Dean

I doubt it....
Put the box on the cool lower part of furnace. Usuallythat ends up
being the same height as a standard wall switch.

OR

Put thebox in the rafters above. Then run steel conduit from that
ceiling box to the furnace.

You should mount the box on the joists or wall, and you need to use shielded
cable.

"dean" wrote in message
ups.com...
Hi all,

I need an electrical wizard to advise me here. I am installing a new
hot air wood furnace next to an existing electrical furnace. I have run
the 20 amp cable along the basement ceiling ok and now I need to drop
down to the furnace. I want to add a cut-off switch so that I can
isolate the thing in an emergency.

Can I put this switch on the plenum? In a metal box? The other furnace
has a small breaker box on its plenum with 3 breakers inside, so I
can't se why I should not be able to do this. I have used standard
orange 10-gauge romex cable.

Plenum temp is set typically to turn on fan at 170, and will open an
emergency heat dump at 200 in case of a problem.

Thanks!

Dean

"dean" wrote in message
ups.com...
Hi all,

I need an electrical wizard to advise me here. I am installing a new
hot air wood furnace next to an existing electrical furnace. I have run
the 20 amp cable along the basement ceiling ok and now I need to drop
down to the furnace. I want to add a cut-off switch so that I can
isolate the thing in an emergency.

In addition to what the others said... When you say you ran it along the
basement ceiling, did it go along a joist, or across them? If it went
across them, it had to go through them instead. You did that, didn't you?
The alternative is to run it way in the corner. The idea is that it
shouldn't be caught by something and pulled down.

Thanks all for the replies. Actually I have not run the cable yet, its
still sitting poking out through the garage to basement wall. I can run
it along the piece of wood that is above the I-beam that goes the
entire length of the basement. The othe rfurnace was done on the other
side of this and passed all its inspections.

Good idea on the mounting it on the lower part of the furnace. If I do
this would I need to put in a junction box on the joist to change it to
encased metal cable, and then run this down?

Or should I put the switch on the joist itself? The ceiling is 9 feet
tall.

Thanks!

Dean

Most codes require that the disconnect be within easy reach of anyone
working on the heater. Some even require one at the top of the basement
stairs. If the ceiling is 9 ft., then mount a box, run BX down, and put the
disconnect on the furnace.

"dean" wrote in message
oups.com...
Thanks all for the replies. Actually I have not run the cable yet, its
still sitting poking out through the garage to basement wall. I can run
it along the piece of wood that is above the I-beam that goes the
entire length of the basement. The othe rfurnace was done on the other
side of this and passed all its inspections.

Good idea on the mounting it on the lower part of the furnace. If I do
this would I need to put in a junction box on the joist to change it to
encased metal cable, and then run this down?

Or should I put the switch on the joist itself? The ceiling is 9 feet
tall.

Thanks!

Dean

Ok great! Thanks.

I called the furnace manufacturer, and they said that the side of the
furnace still gets very warm, even though it is insulated. I am
wondering if there is any standard kind of insulator plate or something
I can put in between the furnace and the disconnect? Any ideas?

looks like you'll need nm cable on an extra 2x4 from the ceiling:
http://www.faqs.org/faqs/electrical-...section-5.html

Just make sure the 2 x 4 is outside the minimum clearances specified on the
installation instructions.

"buffalobill" wrote in message
oups.com...
looks like you'll need nm cable on an extra 2x4 from the ceiling:
http://www.faqs.org/faqs/electrical-...section-5.html