double pole thermostat readings

[jankina]

hello,

I just bought a cottage and I was changing old manual thermostats (connected to electric baseboards 240V) by new programmable ones. One thermostat I removed was a double pole (4 wires), whereas the new ones are all single pole (2 wires). I think making that change is not legal in USA but accepted in Canada (which is my case). So as I was changing the thermostat, I tested all 4 wires (from the junction box) with my multimeter. 2 wires were black and 2 were red. Here are the readings I got, assuming A-B are black and C-D are red : between A-C 240V, between B-D 0V, between C-D 60V (around) and between A-B 60V. I understand the 240V (because both A and C are hot 120V), but what are those 60V readings ??? Someone understands it ?

thank you

[Wgoodrich]

YOU SAID;
I got, assuming A-B are black and C-D are red : between A-C 240V, between B-D 0V, between C-D 60V (around) and between A-B 60V.

A and C are coming from the same romex reading power from panel. C and D are coming from the same romex going to the heater. A and C reading 240 volts is what you need. B and D should read zero volt because the are only connected to the dead heater with no power source. and C and D and A and B are false readings finding some absorption of voltage by the resistance of the heater but no where for the current to flow. Ignore the two 60 volt readings.

Connect your single pole thermostate to the Red wire coming from the panel and to the red wire coming from the heater. These two red wires connect directly to the thermostat. Then the two black wires connect together by a wire nut passing permenant through the thermostat box.

Yes a single pole thermostat is not allowed per Code rules in the US. Reason is you will always have 120 volts to that heater even with the thermostat turned down. The double pole thermostat serves as a form of disconnect in sight of the heaters. YOu did away with the disconnect form within sight of the heater creating added risk of shock when the electrician is now required to go to the panel turn off the breaker and hope no one turns that breaker on while he is working on the heater because he can not see that breaker while working on that heater. That breaker is then unguarded to be turned on by a kid or others unknowingly risking the repairman to shock.

I would take the thermostat back and buy a two pole thermostat if it were me.

Good Luck

Wg

[jankina]

thanks for the fast answer

in fact I already did the connections, exactly as you said but I connected the black wires instead of the red to the thermostat. My understanding is that it makes no difference since both red and black are hot (to get the 240V), is that right ?

About the 60V readings, I was just concerned if that could indicate a kind of a "leek" for the current...

[Wgoodrich]

The heater itself will accept a slow flow of current even when no return path is connected. This affect is the reason you are getting the false reading of 60 volts from a hot wire to the heater wire.

It makes no difference red or black as long as you are breaking between the hot incoming line from the panel and the load line to the heater.

Good Luck

Wg