I've noticed that in many/most modern furnaces the thermostat cable
enters and connects to the control module in the same compartment
with various line-voltage wiring. In fact, much of the line-voltage
wiring terminates on the same control module. There is no partition to
keep the low-voltage and line-voltage wiring separate. This would seem
to violate the frequently quoted rule about separation of low- and line-
voltage wiring unless thermostat cable insulation is supposed to be rated
for line voltage. The thermostat cable I've seen is CL2 with a 105C
temperature rating but says nothing special about voltage. Is it 300V
or 600V rated?

Dan Lanciani
ddl@danlan.*com

"Dan Lanciani" ddl@danlan.*com wrote in message
...
I've noticed that in many/most modern furnaces the thermostat cable
enters and connects to the control module in the same compartment
with various line-voltage wiring. In fact, much of the line-voltage
wiring terminates on the same control module. There is no partition to
keep the low-voltage and line-voltage wiring separate. This would seem
to violate the frequently quoted rule about separation of low- and line-
voltage wiring unless thermostat cable insulation is supposed to be rated
for line voltage. The thermostat cable I've seen is CL2 with a 105C
temperature rating but says nothing special about voltage. Is it 300V
or 600V rated?

Dan Lanciani
ddl@danlan.*com

Manufactures get to do what ever they want when the designs are submitted to
the testing agencies like UL and CSA. I worked for an electrical
manufacture that ran line and low voltage in the same bundle ty-wrapped
together. As long as you see the acceptance sticker on it chalk it up to
the way of the world.

Check out a electric waterheater. Fed with a minimum of #10 and inside the
manufactures use #12.

Air conditioner condensers are the same situation

SQLit wrote:

"Dan Lanciani" ddl@danlan.*com wrote in message
...

I've noticed that in many/most modern furnaces the thermostat cable
enters and connects to the control module in the same compartment
with various line-voltage wiring. In fact, much of the line-voltage
wiring terminates on the same control module. There is no partition to
keep the low-voltage and line-voltage wiring separate. This would seem
to violate the frequently quoted rule about separation of low- and line-
voltage wiring unless thermostat cable insulation is supposed to be rated
for line voltage. The thermostat cable I've seen is CL2 with a 105C
temperature rating but says nothing special about voltage. Is it 300V
or 600V rated?

Dan Lanciani
ddl@danlan.*com


Manufactures get to do what ever they want when the designs are submitted to
the testing agencies like UL and CSA. I worked for an electrical
manufacture that ran line and low voltage in the same bundle ty-wrapped
together. As long as you see the acceptance sticker on it chalk it up to
the way of the world.

Check out a electric waterheater. Fed with a minimum of #10 and inside the
manufactures use #12.

Air conditioner condensers are the same situation


I agree; appliance manufacturers get a lot of leeway from UL.
Practices which wouldn't be permitted by NEC are routinely
OK'd *inside* the appliance where UL feels the mfr has
sufficient control to satisfy some minimal level of safety.

Jim