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Installing Electric Baseboard Heat

February 6, 2007

Today we are going to discuss installing electric baseboard heaters. The first thing you need to do is choose a good location for your heater.

Electric baseboard heaters need to be placed under a window area. The reason for this is the cold air from the window will fall mixing with the warm air that rises from the heater causing the air to flow around the room. However, when placing the heater under a window you need to be concerned about receptacles, furniture and drapes. You must keep all furniture and drapes a minimum of 12 inches from the heater to prevent fires. You are also not permitted to have an electrical receptacle above the heater.

Now you need to decide which type of electric baseboard heater you are going to install. You have the standard baseboard heater and Cadet makes a hydronic electric baseboard heater.

The standard electric baseboard heater, as pictured above, is economically priced but, very inefficient. These units have aluminum fins that surround the heating element. Aluminum disipates heat quickly, so these do not maintain the heat and need to operate more often. These units range in price from $40.00 – $90.00.

Cadet makes a premier hydronic electric baseboard heater they call Softheat, that is considerably more efficient. These heaters are recommended for nurseries, bedrooms and for people with severe allergies. Additional benefits include lower operating and surface temperatures and whisper quiet operation. The Softheat hydronic baseboard uses circulating fluid (80% water and 20% Ethylene Glycol) to provide steady, uniform warmth with longer heat retention and minimal temperature variation. No plumbing is necessary, these heaters are totally self contained. These units range in price from $150.00 – $225.00.

The next decision is a thermostat. A wall mounted thermostat is recommended to provide optimum comfort when heating the room. A unit mounted thermostat is also available. When working with 240 volt units, be sure to get a double pole thermostat.

The final decision is to determine the size heater that you will need. To do this you need to measure the length and width of the room. Multiply these measurements together and then multiply that number by 10. For example, if your room is 10 feet wide by 10 feet long your formula would be (10′ length x 10′ width) x 10 = 1000. For this example you need 1000 watts of electric baseboard heat to properly heat this room. A 4 foot baseboard heater is 1000 watts.

Now that you have figured out that you need a 1000 watt heater you need to size your breaker and wire. To do this, divide 1000 watts by 240 volts = approximately 4.2 amps. You may use 14/2 NM cable, but I recommend 12/2. This circuit will require a double pole 15 amp circuit breaker maximum.

Now you just need to run the wire and install your components. Run a 12/2 NM cable from your breaker box to the wall mounted thermostat. The best location for this thermostat is on an inside wall. Electricians typically place these above the light switch approximately 5′ above the finshed floor. From the thermostat, run another 12/2 NM cable to your heater. If you are going to use a unit mounted thermostat, you just need to run the cable from your breaker box to the heater.

I recommend installing the wire on the left side of your heater. The reason for this is, the Softheat unit can only be wired on the left side. If your budget does not permit you to install one of these Softheat units now, this gives you the option to install one at a later date.

Be sure to correctly wire the thermostat. You will notice it will have a line side and a load side. The line side is the power cable that comes from your breaker box and the load side is the cable that goes to your heater.

If this scenario does not work for your application, please submit your questions in the comment section of this post.


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49 Responses to “Installing Electric Baseboard Heat”

  1. Ken on February 7th, 2007 9:59 pm

    We have one electric baseboard heater in a fairly recent addition. The knob on the thermostat broke and I bought a replacement TStat that would work with single or double pole installation. (2 or 4 wires)
    When I removed the old thermostat I discovered that there are two hot black wires and a bare safety ground screwed to the thermostat’s metal body. The old TStat terminals were not labelled as either “line” or “load”.
    I am confused as how to proceed. I don’t know if I can connect one hot wire to “line” and the other to “load”. The old TStat says: Mears model M7 single line break 9314A. Ihaven’t found any info on this unit.
    Any input would be appreciated.

  2. Administrator on February 8th, 2007 3:11 am

    Hello Ken,

    Thank you for your electrical question.

    It sounds to me like your original thermostat is only a single pole thermostat. This is what is needed for 120 volt heaters. If your heater is 220 volts, I highly recommend installing a double pole thermostat.

    As far as the differences between line and load. The line side is the power supply from your breaker box and the load side is the cable that goes to your heater.

    Is your thermostat wall or unit mounted?

    Is there a white wire in the box or heater?

    Is the breaker that controls this circuit single pole or double pole?

    If you have a digital camera, take a picture of the wiring and email it to me. There is a link to email me on the “contact us” page. Do not disconnect your thermostat, just let it hang on the wires and take a picture. Make sure you turn off the breaker to this circuit before you open up your thermostat.

  3. Administrator on February 9th, 2007 6:42 pm

    I am posting Ken’s email here as I believe this will help everyone experiencing the same problem.

    ————Begin email———— 

    Thank you for your quick response to my question.

    The baseboard heater and 30 amp breaker are both 240 volts and the Stat is wall-mounted. The wall box has two 120v lines with the black wires going to either side of the Stat. (I have the breaker tripped and double-check with a meter except when checking for voltage). I had the Stat disconnected and each black wire read 120v.  The two white wires are joined with a wire nut in the box.

    As I said in my original question, the Stat is not marked line or load. So, there is a hot wire going to each terminal of the Stat.  I am not too familiar with 240, but I expected a load side wire with no voltage when disconnected.  I don’t understand how this works with hot on each side, but it does.

    I just wanted to replace it because the temp adjusting knob broke. It was always hard to turn to set the temp. Every new Stat that I see clearly defines the line and load sides with red and black wires, and that I understand. I can’t rewire if I wanted too because this room has no access from below.  Not even a crawl space like the rest of the house. Have you ever seen a set-up like mine?

    I have attached four photos to help describe the situation.

    Thank you for your time.   Ken

    ————End email————

    Click to enlarge

    I only posted one of the pictures because this one helps me solve the problem.

    The reason you are getting 120 volts on each line is because you are getting a back-feed through the heating element. Your circuit is 240 volts, but a single pole thermostat is only breaking 1 “leg” of the 240 volt circuit. The way this is wired, you are sending 120 volts to the heater at all times.

    You need to turn off the breaker and separate the white wires. In this situation, these white wires are the other hot “leg” of this circuit and not used as a neutral. The next thing you need to do is identify these white wires as hot wires by marking them with a permanent marker or wrapping them with electrical tape.

    Now you need to determine which cable is the line side and which is the load side. There are 2 ways you can determine which cable is line and which is load.

    The first way is, with the breaker off, check continuity between the white and black wires from the same cable. So, you have a cable with a black, white and bare copper that enters the left side of the box and the same on the right. One cable is line and one cable is load. The cable with continuity between the black and white wires is the load side.

    The second way is to turn on the circuit breaker and test for voltage. The cable with voltage on it is the line side. However, I do not recommend this option as it is very dangerous for an inexperienced person to work with live 240 volt power.

    Once you have determined which cable is line and which is load, you may install your double pole thermostat. A double pole thermostat will break both hot “legs” on this circuit and you won’t be constantly sending 120 volts to your heater.

    To hook up your new double pole thermostat, make sure the breaker is off and connect the black wire from the line side cable to one of the line side wires or terminals on the thermostat. Hook the white wire from the line side cable to one of the line side wires or terminals on the thermostat. Do the same for the load side and install your thermostat. Go turn on your breaker and test this circuit.  

  4. Dennis Gormley on April 26th, 2007 4:59 pm

    I just installed a new thermostat to my baseboard heaters.
    The heaters now run continually even if I turn off the thermostat.
    I figure the wiring is wrong. Genius aren’t I?
    The guy at the electrical store said………….hook all the black wires together and all the white wire together……………..guess that was wrong.
    I have a line going directly to the main electrical box.
    Another line coming in from the heater.
    The wires from the thermostat.
    Help if you can

  5. Dana Hendricks on August 23rd, 2007 8:10 pm

    I have read if one installs more than one heater to wire them in parallel. Does one run wires from each heater back to a junction box at thermastat.

  6. Marie on September 21st, 2007 10:11 am

    I am looking to buy condo that has electric baseboard heating. Most of the heaters are 20+ years old, so I am planning on replacing them. The condo is about 1000 square feet and I think it has 5 separate heating units. Would I need one thermostat for all of them, or does each unit get a thermostat? I want to get programmable thermostats because I’m often away for days on end.

  7. 3 new electric baseboard heaters on October 3rd, 2007 12:11 am

    […] If your heater is 220 volts, I highly recommend installing a double pole thermostat. Installing Electric Baseboard Heat (DIY Electrical Wiring Help – Answers to your Electrical Questions) Now a simple explaination (with the 220 volt breaker off ) there should be three wires to connect the with white and black coated wires go to the breaker and the bare wire goes to ground… Now if you have a 220 thermostat on the wall this is where the wire goes to next, wires from the breaker attach to the line side of the thermostat (black and white)—wires that go to heater attach to load side (black and white) and the bare wires […]

  8. ERICH HARRIS on October 23rd, 2007 6:01 pm

    who sells Cadet hydronic electric baseboard heat runs?

  9. cassie on October 29th, 2007 7:30 am

    hi, we are taking our big clunky radiators out- used with natural gas- filled with water, sometimes they work and sometimes they dont heaters out- and replacing them with cadet electric baseboard heaters-what do we have to do to do this?

  10. Ray on November 5th, 2007 9:00 pm

    Can the more efficient type with fluid in them be used in house that will have power off during part of winter? Will the liquid frezze?

  11. donna on November 9th, 2007 2:58 pm

    I bought 2 cadet baseboard heaters my husband hooked them up but they are not heating the rooms where we put them why is that? Is it because we need more watts or voltage at are breaker box. If so he nor I uderstand how to put them in correctly please help us

  12. charlie on November 21st, 2007 10:12 am

    i recently installed a new elec. baseboard heater with a wall thermostat
    in a new addition. i wired a 220 tstat. there were 2 reed line wires on
    the tstat. there were 2 black load wires on the tstat. i put a hot line on
    each of the red lines (l1 l2). i on the black i wired on a white on one and
    a black on the other to the heater. i have power to the heater when the
    tstat is turned up and none when it is turned down. the problem is the
    heater doesn’t make heat. the return line is the bare copper wire. some
    where something is not wired correctly. can you help me.

  13. Rudy on November 26th, 2007 8:09 am

    I just replaced two baseboard heaters. 220 volt for each. When I replaced the one heater there were three separate lines coming into this heater. I know the one goes to the other heater I replaced. I traced that wire. I also know that one of the lines comes in from the thstat. I don’t know where the other goes but it looks as if it goes back to the circuit breaker. I have the line from the thstat that also goes into the breaker box. I only connected the lines from the thstat and the other heater. I did not connect the line that appears to go directly into the breaker box. My problem is the heaters come on but are very hot. After awhile that go off and then I need to turn the thstat higher to hear a clicking sound and then they come on again. This isn’t the way the original heaters worked. Could it be my thstat has gone awry and I need to replace it. Or is that third line necessary to connect.

  14. Walter Carnahan on December 1st, 2007 11:15 pm

    Just bought new Cadet heaters for my house.
    If I mount them above the existing gas forced air registers will that damage the electric heater because of uneaven air flow?

  15. gary on January 22nd, 2008 6:07 am

    I just replaced two baseboard heaters with hydronic heaters . My problem is i started to replace the thermostat with a programmable one ,and i took the old one off and it only had 3 wires on it Do i need one with 4 wires ? Can anyone recommed a good tstat and the hookup procedure?

  16. Wayne Gilchrist on January 27th, 2008 1:15 pm


    Is your old thermostat a single pole thermostat? What color are the 3 wires that are connected to this thermostat?

    If you are using 220 volt heater, then I highly recommend installing a double pole thermostat. Most line voltage, double pole thermostats require 5 wires (2 – power in, 2-power out and ground).

  17. Robert on April 24th, 2008 9:41 pm

    I have baseboard heaters in my house, and recently the two that are hooked together in my living room will occasionally not turn off when it reaches the desired heat. In fact it won’t turn off at all. It runs until the house is like 85 degrees and still keeps on cranking out the heat. I have to turn off the breaker for awhile and then when I turn it back on, it will resume functioning normally until later…sometimes a few days, sometimes a week and then I have to do it over again. Any tips?

  18. Frank Geddes on July 9th, 2008 8:57 am

    I am reinstalling two singer baseboard heaters. How high above the vinyl should they be hung on the wall? In other words, how much space, if any, should be between the vinyl floor and the bottom of the box?

  19. Art on July 16th, 2008 9:16 am

    I am considering installing electric hydronic baseboard heaters to replace my 65 year old eating system (oil boiler and radiant (in concrete slab)heat).

    Is the junction box within the heater sufficient to eliminate the need to have an electrical box at each heater?

    If I keep the amperage under the load rating of the wire/circuit breaker, can I feed more than one T-stat with the same line running from the breaker box?

    I have a very small room (6’x9′). Is it feasible to feed this with a wall T-stat that runs a bigger area and also use the built in t-stat?

    I have a room with 2 outside walls with only one with a window. Is it necessary (or highly recommended) to put 2 smaller wattage heaters on both walls versus 1 larger unit on the wall ith the window?

    In addition, are there any special considerations when installing one of these in a bathroom?

    Thanks in advance, Art

  20. Brian on July 16th, 2008 5:37 pm

    Hello, not sure if anyone might be ableto answer this question. I have a couple of 110 volt radiant cove heaters. I have a double pole single throw thermostat. I was wondering if I could use the single thermostat ( rated at 22 amps at 110V) to run two heaters using indivuals circuits. That is one heater would be on a 20 amp single breaker, the other heater would be on another 20 amp single breaker. Each heater draws about 9 amps. I was wondering if I could wire these to the two pairs of wires on the double pole thermostat to heat my attached garage. I’d apprcaite any thoughts.
    Brian in Cheyenne

  21. Ken Iman on October 22nd, 2008 11:00 am

    Hi, I am replacing a dial type thermostat with a digital one for my 220v baseboard heat. The old dial one has two red wires on top and 2 black wires on the bottom. The new digital thermostat has 2 black wires. Do I hook up the two reds together to one black and the two blacks to the other black wire on the digital thermostat?

  22. Diane on October 22nd, 2008 6:26 pm

    Question I am installing a 110 volt cadet baseboard heater and I would like to install a double pole thermostat so that it can be turn off. I understand from the website that I bought it from that the double pole thermostat that goes in the end of the baseboard (vs wall mount) can be used.
    Can you please tell me how the wiring should be since there are 4 wires on the thermostat breaking both sides of the wires.?

  23. Charlie Williams on October 26th, 2008 5:04 pm

    Hi, I am replacing a dial type thermostat with a digital one for my 220v baseboard heat. The old dial one has two red wires on top and 2 black wires on the bottom. The new digital thermostat has 2 black wires. Do I hook up the two reds together to one black and the two blacks to the other black wire on the digital thermostat?
    Is it possible to send you a picture of my wiring?

  24. Joseph Casha on November 3rd, 2008 5:40 am

    I want to add a 3ft hydronic electric heater to an existing 2ft heater and use the same thermostat . The 2ft heater is in the bathroom and the additional heater
    with be located in a closet which is directly opposit the bathroom is there a
    specific wiring configuration i need to use. If so,can you give me a heads up
    on the correct wiring Both heaters are 240volts.

  25. Milton on November 4th, 2008 1:18 pm

    I am currently adding the electric baseboard heaters to my home and I would like to know if the units require there own seperate breakers or if they can be wired in such as multiple units on one breaker or on with other electrical recepticles. I have been unable to find a wire diagram for this issue.

  26. Eric Sheppard on November 16th, 2008 7:59 pm


    Would you please explain the physics of what happens to the wattage on two baseboard heaters of different wattages (ex. one 2000 watt and the other 1000 watt) when they are connected to the same thermostate. However the connection between the heaters is through the wires directly coming from the end of each heater?

    Thank you,

  27. MICHAEL on November 19th, 2008 5:33 pm




  28. Gerard Edwards on November 20th, 2008 8:39 pm

    Hi I am installing Thermostats for my Baseboard heaters what kind of a box do I use to mount the thermostats to. kindly appreciate your answer Thank you

  29. travis on November 30th, 2008 2:54 pm

    i have instaled a 6ft heater in a room about 11×15 fully insulated and no windows. i know thats over kill but it really seams hot in this room ,even when the base mounted therm is even on less then low. could this be a wiring problem? all works well and no kicked breakers. could it just be that warm? thanks, travis

  30. mark on December 2nd, 2008 10:09 am

    I installed 2 baseboard heaters 1 -4 foot unit ganged to a 6 foot unit, for some reason the 4 foot unit get alot hotter than the 6 foot unit . The 4 foot unit is first than ganged to the 6 foot unit. I even reversed the heaters so than the 6 foot unit is first with the same result can you help me?

  31. Les on December 5th, 2008 10:49 pm

    Thanks for the tips on replacing a single pole thermostat with I programmable. I’m installing a Honeywell TLb230A and I have the same set-up as Ken did.

    By the way, will it reduce my electric bill by eliminating the constant 120 Volt load on the heater? I assume that it does not until the thermostat completes the circuit. Otherwise it would always be warm.

  32. Gerard Edwards on December 6th, 2008 9:47 pm

    how do you hook up the 240v forced fan wall heaters? I have 2 wires coming in from the panel box and there are 3 wires on the heater. it has a built in thermostat. would appreciate any help.

  33. Anne on December 15th, 2008 9:19 pm

    I had 4 electric baseboard heaters installed. They are warm to the touch but do not put out any heat at all. They are all wired to extension cords and plugged into outlets above them… I don’t think that is exacltly up to code? how do I re-wire the heaters correctly?

  34. tim on December 16th, 2008 9:42 am

    there is a commercial building that has romx and mc cable running thought out the building, can this be done this way

  35. JEFF on December 21st, 2008 3:25 pm

    Can I hook up (wire) two (a 4′ and 6′) 220 volt hydronic heaters together into one 20 amp breaker as the amps will only be 11 amps total? Does each 220 heater have to be feed to it’s own breaker and not together. It doesn’t seem fair to hook up a 4 amp heater to a 20 amp breaker, isn’t that a waste of breakers? Please call me at 516 835-9404 with a quick answer. Thanks… Jeff

  36. Annalisa on January 5th, 2009 8:21 am

    Hi, we recently had our basement done, carpet was removed and tile was installed. Our contractor raised our baseboard heaters off of the ground and it is now about 1 foot from the floor (probably a little less). It looks strange to me and I was wondering if this is normal or even safe?! Do you think we should have him move it closer to the floor like normal?

  37. Steve on January 25th, 2009 6:55 pm

    I’ve just had to replace an electric baseboard heater. The original was 8 feet long but I opted to replace it with 10 feet (two five foot lengths wired together). The electrician did the job and everything is working okay. The heater is still new and smells a bit (this is normal). But what I noticed is that the heater really doesn’t get as hot as the old one. I can touch the outside edge and even (momentarily) touch the heat-spreaders inside. Will this change as the heater “breaks in” or is it some new “safer” standard or is it something different all together? The heater is a standard type (not hydronic) on it’s own 220 volt 20 amp circuit.

  38. Madeline on January 28th, 2009 7:58 am

    I hope you can answer a (not so) electrical question…We are installing hot water baseboard heat…Can you tell me where this should be placed? There are two outside walls in the room, each with windows.
    Thank you.

  39. Greg on February 2nd, 2009 10:25 am

    I am trying to determine the wattage of two 2000 watt baseboard heaters wired in parallel.

    Some texts show total watts as 4000. Simple enough right but doesn’t the parallel wiring drop the power consumption to

    (2000×2000)/(2000+2000) = 1000

  40. Viola on May 28th, 2009 10:35 pm

    Can you simple explain how to convert baseboard heat thermostat from single to double pole? Also if I replace the baseboard itself, is there anything special I have to do… or should it be easier than the thermostat?

  41. Matt Vaudrin on June 12th, 2009 3:18 pm

    Wondering if somebody can help me out, or point me in the right direction anyway.

    I have an electric baseboard heater in my room. Even when the thermostat knob is all the way down (the lowest setting), it will still turn on (it’s never that cold in the room though).

    like today, it was almost 80 degrees outside, the knob was all the way down as far as it could go and the heat still came on. The knob won’t turn “off” anymore, so there’s nothing to do except wait for it to go off on it’s own (which is annoying when it’s already warm in the house).

    Anybody know if there’s a simple way to disconnect the heater (then I can reconnect when winter comes around again)? Or would I need to call an electrician for that?

  42. D Stitt on August 28th, 2009 12:24 pm

    I am considering buying an older home–built in the 1940’s. It is currently being heating with electric baseboard heaters that were put in 9 years ago.

    The house is about 800 square feet–more like a cottage–on a lake–second tier.

    The basement is finished with 1? heater there. The upstairs is where the bathroom, small living room and bedroom are located.

    The house has been updated and very neat.

    My main question is, is it safe to leave baseboard heat on in my absence, sometimes for several days at a time?

    Thank you for anwering right away as I am seriously considering the purchase.

  43. Douglas on November 28th, 2009 11:26 am

    can i run more than one 1000 watt baseboard heater on one line,using baseboard thermostates

  44. Bob on December 30th, 2009 5:10 pm

    I want to install electric baseboard heat in a room. My question is can these units be seated directly on drywall?

  45. Jerome A. Pollard on January 5th, 2010 8:35 am

    I have electric baseboard heaters in my house and I have a question about installing an additional one.

    I would like to install a small one (no more than two feet) in the bathroom. However, on the wall opposite to where I want to install this new heater there is another baseboard heater. My question is can I connect the new baseboard heater to the baseboard heater on the opposite side of the wall?

    Also where is the wiring on the baseboard heaters that I would use to connect them.

  46. robert on January 7th, 2010 9:11 am

    How do I wire a 240v baseboard heater with thermostat on heater

  47. Philip on January 22nd, 2010 8:02 am

    I have a 12X18 home office with electric baseboard heat mounted beneath windows on the east wall. On the opposite wall is the thermostat, next to the entry door in one corner. I know this is the standard layout but I would like to move the baseboard heater to the (inside) wall where the thermostat is, and put a full length counter/desk/drawerbank/workstation on the east wall beneath the windows.

    Not exactly kosher, but are there any major red flags?

  48. Luc Filiault on June 1st, 2010 6:29 pm

    I am installing 4 1500 watts 240 volts electric hydronic heaters with one thermostat which makes a 6000 watts circuit. If I am doing the calculations correctly I would need a 40 amp circuit. What size wire would I need?

  49. DENNIS on January 11th, 2012 7:11 pm

    I have MEARS CEILING HEAT SYSTEM thru out my home. MODEL M-7 18 amp 125, 250 vac. single line break 190 L 360 . There was a roof leak and caused the ceiling in my kitchen to bow downward. This is about a 2 foot by 8 foot area. I would life info. and diagram of the installation so i can figure out where the heating wires are located. I need to either change out the drywall sheeting or secure 2bys in the attic between the ceiling josts and screw the bowed drywall to the 2bys. I don’t want to do anything until i’m sure i know what to do and how to do it ” WITH OUT SCREWING INTO THE HEAT WIRING AND SHORTING IT OUT ” Would not be a good thing !!! HELP THANK YOU “”” HAPPY NEW YEAR USA AND THE WORLD DENNIS