Baseboard thermostat question

[kmsuzuki]

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:

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:

... 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.

[Chris Lewis]

According to :

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.

[Travis Jordan]

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.

[Ken]

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?

[Travis Jordan]

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