Calling on a DU electrician.....

[Tripper11]

Simple, yet importante question. I am in the process of replacing my daughter raggedy thermostat with a new one.
When I removed the old one I was overjoyed:sarcasm:to find that both wires to the original are black. No indication of which wire is positive or negative.
There must be a way to determine which is which? Any help would be greatly appreciated.
Cheers

[Robb]

1. Plumber here, but kinda handy

...It shouldn't matter. The thermostat is closing a circuit to turn the furnace/whatever on and off.

For example, just twist those wires together and stuff turns on. Disconnect them, they turn off. I think you can't go wrong here.

[WhollyHeretic]

3. I'll second that

It can go either way, it's just completing the circuit.

[conscious evolution]

2. Were the terminals on old thermostat marked?

And do you remeber which wire was on which?
2 wires.Now that I think about it it might not matter.A 2 wire thermostat is just a simple switch.Sorta like a light swith,only instead of 120 volts AC it will be a cery low DC voltage.
Can you copy the wiring schematics that came with it and post here?

[Tripper11]

4. Thanks for the input.....

Here's how I figured it out while waiting. I have a tester, and turned the power on with the ground wire exposed as well. When I touched the positive and the ground I got a postive for power. When I touched the negative with the ground I got nothing, thereby concluding that Left was positive and right was negative....
And oh, on that note I've also come up with a new mantra while running back to the bedroom mubmling to myself...."left is positive, right is negative"...I think after this week this mantra can also apply to the elections!


"Left is positive, right is negative!"