Electrical Wiring in the Home/thermostat


QUESTION: It wouldn't let me follow up on your answer in the last post. But yes, it is as you describe except that it is a 12-2  and not a 10-2

Thanks, Stephan

on board thermostat
on board thermostat  
ANSWER: HeyStephan,
ok the way you have it i cant see it ever working "Properly" and would most likely always be warm because you would NOT be breaking BOTH legs you do however have options and would unfortunately involve some work the easiest would be to simply bring the 10/3 "feed" to the thermostat.Next you would have to run an additional 12/2 cable from the heater to the thermostat and lastly the easiest would be to purchase thermostat that goes directly on the heater. And the reason being is you need to be able to break BOTH LEGS and not just one. And by having that 10/3 cable going to the thermostat you would than be able to take the 3rd wire of the 10/3 and ground it to the ground of the thermostat.I took the liberty of posting a diagram for you showing the way it should be wired.So to recap ;
1-Relocate the 10/3 from the heater to the thermostat
2-Add an additional 12/2 cable from the heater to the thermostat and splice the 12/2 black to black and white to white from the 12/2 to the 12/3 thus bringing the feed to the thermostat.
3- purchase a on board thermostat.
☆☆Work Around☆☆
If you like you can simply use what you have in place and use the 4 wire thermostat as a Single pole thermostat and just break 1 leg However you will ALWAYS have power present at the heater and run the risk of one side of the heating elements constantly "warm" EVEN with the heater off.If thats something you would like to do let me know and ill tell you how

---------- FOLLOW-UP ----------

QUESTION: Oh ok, a little more work than I thought it would be. I'll run another 12 -2 to the thermostat since I have that  still all open. Thanks so much for  for your help.

ANSWER: Cool im glad you opted the safer and more correct route, now keep in mind all your going to do after you run that 12/2 is splice the black to black and the white to white of the 10/3 and if your using romex which would be better because u will also be able to bring the ground up to the T-stat as well...after you do that your going to connect the black and white of that 12/2 to L1 and L2 and it doesn't matter which one you connect to what than on the other 12/2 6ou have going TO THE HEATER your going to connect to T1 and T2 of the Thermostat and than in the heater your going to connect the black and white of the 12/2 to eqch of the legs of the heater...if you keep the colors the same it might be a bit easier I know it sounds like alot but its pretty straight forward and ill always be here for you should you need additional help...
1- Run a piece of 12/2 romex from heater to thermostat
2- Connect the black wire from the 12/2 to the black wire of the 10/3
3- Connect the white wire from the same 12/2 to the white wire of the 10/3
4- Cap them off your done with that
5- Connect the black wire from the existing 12/2 to 1 of the heater wires cap it.
6- Connect the white wire from the same 12/2 to the second heater wire cap it.
7- Connect the black wire that you just connected to 1 of the heater wires to T1 of the thermostat
8- Connect the white wire that you also just connected to the second heater wire to T2 of the thermostat
9- Connect the black wire of the new 12/2 wire that you connected to the black wire of the 10/3 feed to L1 of the thermostat
10- Connect the white wire of that 12/2 which is connected to the white of the 10/3 to L2 of the thermostat.
11- GROUNDS- splice any or all your grounds to the heater itself if you have more than 1 ground at the heater simply splice all together and add a tail than using a self tap screw connect your ground tail to any metal part of the heater casing
12- do the same at the thermostat.
Now i ask of you can you please fill out the survey it helps me greatly and allows me to help more people in need.

---------- FOLLOW-UP ----------

QUESTION: Hi Robert. It seems that I can not pull a another wire because of obstructions. And I'd rather not tear apart the wall.

I think what was existing was that it was used as a single  pole thermostast. It did seem to turn off completely. Would it still be drawing power (I. e. Costing money?), even when the thermostat is in the off position? Or it just means one pole  wire is hot at the heater?

What's there now at the heater is red power leg goes to heater. White is capped. Ground goes to heater screw. Black power leg goes to thermostat T1. ground is capped. Then L1 goes back to the heater.

Thanks again, Stephan

I cant be certain for sure stephan if its not going to be pulling a draw if it is off and the one leg is connected without an amp probe and that will be basically the only way to tell HOWEVER if you have the thermostat off and its not warm than that would be a pretty good indication that its not...Also keep in mind you can still get the thermostat that mounts right to the unit itself at homedepot and you have ALL the wires you need in one place...keep that in mind
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Electrical Wiring in the Home

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Robert Tomasulo


I am here to answer ALL your questions regarding anything to do with home wiring such as Switches, Receptacles,Lighting, Main Distribution Panels, HVAC, Thermostats, etc; if it has a wire and in your home I CAN ANSWER IT. Whether its as simple as "why do my lights flicker?" Or as complex as I would like to rewire my house im here to help, in addition i can offer advice on remodeling a kitchen or lighting up you back yard as well as offering troubleshooting on appliances.


I have over 17 years in the electrical industry including Residential, Commercial & Industrial, Im also a certified HVAC technician as well as a certified fiber obtic technician.I am currently employed by the New York City Transit Authority as the Senior Electrical Maintainer and serve as the Relief Foreman for the electrical maintenance division for the past 12 years.I also hold many certifications, licenses and certificates in my field

FOA Member(Fiber Optic Association) UTU (United Transportation Union) IBEW (International Brotherhood of Electrical Workers) HVAC/TALK (Heating & Air conditioning troubleshooting group)

5 years of technical school after high school in electrical installation and design sponsored by Local 3 (IBEW) As well as over 17 years of hands on in the field training and education, and till this day im still learning, Not a day goes by that i don't learn something and if i feel i didn't i will open up a book to insure I DO!

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