I have a digital thermostat controlling three baseboard heaters in my
finished basement, and I'm looking to upgrade it to a programmable one.
I'm uncertain whether I should go with a single-pole unit or a
double-pole unit.

Here is a photograph of the existing Cadet C2002 thermostat:
http://snice.net/thermostat.jpg

Retailers list this unit as single-pole, but wiring descriptions for
single-pole thermostat's done seem to jive in terms of number of wires
and color of wires. I'm looking to replace this with a Honeywell
single-pole unit:

http://content.honeywell.com/yourhom...ats/CT1950.htm

.... and just wondering if the CT1950A (two-wire) can replace my unit,
even though it has 3 wires?

Also, I get this vague sense of "you can get away with single-pole, but
you might want to go double-pole.." If safety or robustness is an
issue, I'll just go double.

Thank you.

According to :
I have a digital thermostat controlling three baseboard heaters in my
finished basement, and I'm looking to upgrade it to a programmable one.
I'm uncertain whether I should go with a single-pole unit or a
double-pole unit.

Here is a photograph of the existing Cadet C2002 thermostat:
http://snice.net/thermostat.jpg

Retailers list this unit as single-pole, but wiring descriptions for
single-pole thermostat's done seem to jive in terms of number of wires
and color of wires. I'm looking to replace this with a Honeywell
single-pole unit:

http://content.honeywell.com/yourhom...ats/CT1950.htm

... and just wondering if the CT1950A (two-wire) can replace my unit,
even though it has 3 wires?

Also, I get this vague sense of "you can get away with single-pole, but
you might want to go double-pole.." If safety or robustness is an
issue, I'll just go double.

As I understand it, both the NEC and the CEC permit single-pole thermostats
for 240V heaters, despite the fact that switching only one pole means
that the wiring in the heater remains live w.r.t. ground.

Two pole is safer (the guts of the heaters are, theoretically at least, dead
when the thermostat is off), but you'll find that particularly with electronic
controls, they usually cost MUCH more and are harder to find.

Tho, that CT1950B seems to be a dual version, if your local has it in
stock and it doesn't cost much more, I'd recommend it.

Your existing thermostat probably has three wires so that it can maintain
power inside itself (it gets power from both hots) while the heater
is switched off. The CT1950 models probably get power by "leaking" a small amount
of current through the heater element.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

Chris Lewis wrote:
Two pole is safer (the guts of the heaters are, theoretically at
least, dead
when the thermostat is off), but you'll find that particularly with
electronic controls, they usually cost MUCH more and are harder to
find.

Tho, that CT1950B seems to be a dual version, if your local has it in
stock and it doesn't cost much more, I'd recommend it.

Of course, unless wiring for the other half of the circuit is neatly
tucked away behind that wall (it might be, can't tell from the picture),
you'll have to rewire in order to use the 2 pole CT1950B.

Thanks for your responses, guys.

To paraphrase your responses, I have a single-pole thermostat now (the
Cadet C2002) and I should be fine to upgrade to the Honeywell CT1950A.
Is that right?

Ken wrote:
Thanks for your responses, guys.

To paraphrase your responses, I have a single-pole thermostat now (the
Cadet C2002) and I should be fine to upgrade to the Honeywell CT1950A.
Is that right?

Yes, although if the wiring is present I would use the CT1950B.

According to Travis Jordan :
Ken wrote:
Thanks for your responses, guys.

To paraphrase your responses, I have a single-pole thermostat now (the
Cadet C2002) and I should be fine to upgrade to the Honeywell CT1950A.
Is that right?

Yes, although if the wiring is present I would use the CT1950B.

Ditto. I always prefer double pole over single for 240V, even if you
don't _have_ to.

Travis, as for this:

Of course, unless wiring for the other half of the circuit is neatly
tucked away behind that wall (it might be, can't tell from the picture),
you'll have to rewire in order to use the 2 pole CT1950B.

Good call. I don't even like running 120V lights with "switch loops" (I
prefer to run power to the switches first), let alone single legs of
a 240V circuit. But you never know, best to point out the possibility.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.