Hi All,

I am replacing a wall thermostat for a Cadet wall heater with a programmable thermostat. My box has more wires than I was expecting - I need advise on how to hook it up.

The box:
2 black wires coming from the top of the box (electrical supply)
1 black wire coming from the bottom of the box (heater)
2 white wires from the top
1 white from the bottom
2 ground wires from the top
1 ground from the bottom

New thermostat:
1 black L1 wire
1 red L2 wire
1 black load wire
1 red load wire

Neither the box or the new thermostat have a green screw for the ground wires.

Previous setup with old thermostat:
Black top wire was connected to top black wire
Black top wire was connect to black thermostat wire
Red thermostat wire was not connected to anything and looked burnt
All 3 ground wires were connected and one was connected to green screen on thermostat.

Per instructions for the new thermostat:
Connect black wire from the top of the box to thermostat black L1 wire
Connect white wire from the top of the box to thermostat red L2 wire
Connect black wire from bottom of box to thermostat black LOAD wire
Connect white wire from bottom of box to thermostat red LOAD wire
Connect all ground wires.

Questions:
Is it okay just to have all of the ground wires connected and not connected to a green screw?

What do I do with the extra wires?
- Black from the top of box
- White from the top of the box

Thanks for the help!

I assume this a line voltage thermostat for a baseboard or some other type of electrical resistance heat, correct?

If there is no connection for the ground on the thermostat keep the ground wires connected together and if mounted in a metal box make sure the box is bonded to the ground. The whites would stay together and your black load wire would go towards the heater and the black line would be connected to the source. Not sure what the reds are for. It sounds like it could be used to control two different heaters with two separate lines (supply) and two different heaters (Load).

I will bet those are 240 volt heaters, and you have/need a two-circuit plate thermostat. reds on one thermostat circuit, blacks on the other.

the box had darned well better be grounded to those ground leads, and a pigtail to the faceplace of the thermostat if it has a ground screw. should be a hole in back for a #8 ground screw. if not, I'd use a green "box clip." wire nut things for safety and use a "squeaker" or "growler" non-contact power tester on the whites. if they don't start it beeping when the breaker is momentarily turned on, they're neutral as they're supposed to be, breaker off, and pigtail them together.

do please pull the circuit breaker and use a non-contact "squeaker" power tester before working with those wires. it's not close enough to Easter to home-smoke the hams

if that is //NOT\\ a line voltage thermostat, take it back, get another. you might have to ask a clerk to get steered to the right place. hint: you don't have five brands and 20 models to choose from, you have probably one. if they can't help you, hit an electrical supply house (many sell to plain Joes, but at full retail one-sy price) or a fleet-and-farm store. if you have a sales tax permit for any business, you can go to the Will Call counter at Grainger and buy it there.

This message has been edited. Last edited by: swschrad,