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  • 220 V baseboard heater wiring

    Hi .. i have just purchased 3 220V baseboard heaters with individual double pole thermostat .. the wiring direction that comes with the product is not as clear as i was hoping to .. i have no problem with 110 Volt wirning but never done 220V wireing .. does anyone know how to wire these 3 heaters together? Thanks.

  • #2
    Wiring 220V is no more difficult than wiring 110V. You get twice the power (watts) from the same size wire. That's why it's used.

    In your panel you have a bus with alternating legs. A two pole (220V) breaker attaches to both legs and has two lugs for the two hot wires to attach to. Run the two hot legs and a ground to the baseboard heaters, through the t-stat. Without knowing the loads, wire size cannot be determined. The heaters should have watt ratings. add up the watts and divide by the voltage to determine the amperage draw. You can then go to a wire size chart to determine proper wire size.

    Just check to make sure the unit with the t-stat can handle the two units downline. The t-stat must be capable of handling the total load if you wire it this way.

    Comment


    • #3
      Bigtom -- thanks for the reply .. that extra hot wire from 220 is what has confused me .. i guess like u said, it is the same as 110V .. just have to try to draw the diagram on a paper and take it from there .. couple questions though:

      1- I am having a seperate t-stat for each heater, is that OK?
      2- with the 220v circuit, there are 4 wires .. 2 will be balck (hot), one will be white and one ground. You mentioned about the 2 hot and the ground .. where will the white be connected in the heater .. The heaters have not been shipped to me yet so hard for me to get the picture!

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      • #4
        There is no neutral wire for baseboards, they are not like stoves or dryers that also contain 120 volt components so there is no need for a 4 wire configuration. You have 2 hots and a ground (usually 12/2 wire is used for baseboard heating). Up here the baseboard heater wire has a red sheath and contain black and red hot conductors with bare ground.
        If you are using the regular stuff with black, white and ground make sure you mark all ends of the white wires with black tape to indicate they are hot.
        A separate thermostat for each heater is fine, you just wire all the line sides of the thermostats in parallel (same as you would do for outlets)

        If all the heaters are in the same room I would suggest using a wall mounted thermostat to control all the heaters. It is easier to maintain temperature as they are calibrated in degrees instead of the usual turn this way for hotter indicator on the rad based thermostats. Also all the heaters turn on at the same time to provide a more even heat at living level instead of at floor level. Also easier to turn them all off so you don't waste power

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        • #5
          now i got it .. i was looking for a neutral wire in the diagrams .. that's what was confusing me .. I have a couple more questions ..

          Is this correct calculation for the breaker size:

          4500W/240V=18.75 Amp .. give it 80% cushion, that would make it to a 30A breaker .. is that correct?

          So what type of breaker am i getting? (other than being 30Amp). Is it one of the smaller size ones or the ticker type that is used for my Dryer?


          Also, if i have a 30amp circuit, do I run a 10 or 12 gage wire? I read some place i need #10 CU. and what is CU?

          Thanks all.

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          • #6
            switchex, I will let one of the more knowledgable folks answer your wire gauge question, but I would assume it should be #10 for a 30 Amp breaker. The CU most likely stands for copper (element for copper is CU, where old wiring sometimes used to be AL for aluminum).
            Still enjoying all 10 fingers!

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            • #7
              You need a two-pole breaker (like your dryer has), 10/2 copper romex with ground, and color the white wire black with a marker or electrical tape, as it's being used as a hot conductor, not a neutral in this case.

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              • #8
                i thought every circuit needs to have a neutral for return.. if i am using the white and balck of my 10/2 wire for hot, and bare as ground, what will happen to the neutral? I have to go take a look at my dryer tonight to see how it was wired . .maybe that would answe my question.

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                • #9
                  a 220V circuit uses two hots, no common. There is no "return" on Alternating Current, there is on Direct Current.

                  Alternating current works as a potential voltage between two conductors. Voltage is a measurememt of that current. The system we use in the US is 220V run to your house along with a ground. Your 110V is created by taking only half of the 220V by running one leg of it to ground. This is why the common and ground attach to the same bus at the main panel.

                  Your dryer (if it's not ancient) uses the neutral leg for the 110V in the controler circuit. Your electric range would be the same. The actual heating element on the dryer and range use only the two hots. The manufacturers could make the controll circuits 220V and not use a neutral at all but that would be non-standard and confusing.

                  Your baseboard heater uses a mechanical switch for the t-stat so the only power consumed is the heating element. There is nothing in there to use a neutral wire.
                  Last edited by BigThom; 10-09-2006, 10:19 AM.

                  Comment


                  • #10
                    Re: 220 V baseboard heater wiring

                    Originally posted by BigThom View Post
                    Wiring 220V is no more difficult than wiring 110V. You get twice the power (watts) from the same size wire. That's why it's used.

                    In your panel you have a bus with alternating legs. A two pole (220V) breaker attaches to both legs and has two lugs for the two hot wires to attach to. Run the two hot legs and a ground to the baseboard heaters, through the t-stat. Without knowing the loads, wire size cannot be determined. The heaters should have watt ratings. add up the watts and divide by the voltage to determine the amperage draw. You can then go to a wire size chart to determine proper wire size.

                    Just check to make sure the unit with the t-stat can handle the two units downline. The t-stat must be capable of handling the total load if you wire it this way.
                    BigThom,
                    I am trying to install 3 baseboards on a single circuit. 1x1500W + 2x500W. They are in the same room so I am putting them on the same Thermostat (Honeywell RLV4300 http://customer.honeywell.com/techli.../69-1918EF.pdf) As far as I can read from the wiring diagram of the thermostat (4 wire version), I can directly wire the red/black hot wires from the breaker panel and the red/black wire to the first baseboard into the junction box, with the two reds connected together and each of the blacks connected to the two wires coming out of the thermostat. Since there is no neutral, the only other wires in the box are the two grounds.

                    My question is that I was having problems getting any power to the system, and I think your explaination of the 110 vs/ 220 mounting has narrowed down where my problem is. I also have lots of 110 wring experience but aside from wiring dryers and ovens, have no 220 experience, so I think my problem is at the panel.

                    I have wired the two hot red/black wires into a 15 amp single pole tandem Square D breaker. Each wire has 15 amps, but I think my problem is that since it is a tandem breaker, I can't get 220V out of the two of them. Do I have to use two single pole 15 amps with a bridge to reach the alternating legs of my panel bus? My problem is I'm low on space in my panel for breakers and was hoping to save some with the tandem, but if my hunch is correct, then I will have to remove to other single 15amp loads, replace them with the tandem, and get a bulkier breaker for the baseboards.

                    Or, could I use two tandems side by side and wire the two hot red/black from the middle two breakers?

                    What are your thoughts?
                    Last edited by HandyCanuck; 01-28-2009, 11:09 AM.

                    Comment


                    • #11
                      Re: 220 V baseboard heater wiring

                      You need a double pole breaker(or two singles with a tie bar) to get 240v since each side of the breaker picks up on a different phase. The two phases are 180degrees out of phase with each other and there is 240v across them.

                      If you have an old Federal Panel you can place a double pole breaker across one phase and it will not work.

                      Comment


                      • #12
                        Re: 220 V baseboard heater wiring

                        You said you wanted to hook up 3 (220v) heaters to one t stat. You said the heaters are (1) 1500 watts and (2) 500 watts. That is a total of 2500 watts. That is about 11 amps on a 220v line. You only need to use #12 wire and a 2 pole 20 amp breaker. Here's how to wire it.
                        Start with a #12 romex, connect it to a 2 pole 20 amp breaker to your at your panel. Connect black wire to one pole of the 2pole breaker and the white wire to the other breaker. Mark the white wire with a piece of black tape to indicate it is being used as a hot. Ground the bare wire to the ground bar. Run the #12-2 romex to a large single gang box where you want the T stat (usually 5' off the floor) run a second #12-2 romex out of that same box to the first heater, from that heater, run another #12-2 to the next heater. then a another #12-2 to the last heater (just like you would with 120v outlets in a string) At each heater connect the white and black romex wires and also connect the heater wires. Just like you would with outlets in 120v. Then, back at the T stat box, Take the black and white wire coming from the breaker panel and connect those 2 wires to the T stat marked "LINE". Connect the white and black wires going to the heaters to the T stat wires marked "LOAD". I assume this is a line voltage T stat.
                        That's it.

                        Comment


                        • #13
                          Re: 220 V baseboard heater wiring

                          QROKING

                          Has it right except I would use red tape on the white wire to mark it as L2, the other hot. Black will be L1. Be sure to red tape the white wire in junction boxes and in the heaters.

                          This is all assuming you're going to use a 2 pole, single throw, line Voltage thermostat which keeps things pretty simple.

                          Quick question: Are all the heaters in the same area? If not there may be a need for additional thermostats.
                          Last edited by Woussko; 02-01-2009, 06:18 PM.

                          Comment


                          • #14
                            Re: 220 V baseboard heater wiring

                            Great thread, very helpful.

                            I have been struggling with this question myself, but mostly for wiring the thermostat.

                            I understand now that there are two hots ---> Black & Red (or re-labeled white).

                            I understand that the neutral white (if present) is not used.

                            I understand that we have the bare ground wire being tied together everywhere including to the chassis of the baseboard heaters and all j-boxes.

                            What I don't get is that Home Depot only sells 220v line Honewell digital baseboard heater thermostats that only interrupt ONE of the TWO hot wires (Red or Black). In other words, the thermostats for baseboard heaters around here are all SPST, when I expected them to be DPDT to interrupt both hot wires in the circuit.

                            This is where I get confused. If I only interrupt one of the hot wires, aren't I unable to fully shut off the 220v baseboard heater, and will just be running 110v through this heater in the off position? On other web-sites I see Honeywell 220v DPDT digital baseboard heater t-stats that interrupt both hots (Red & Black) which makes the most sense to me. Can't seem to find the DPDT thermostats here in Canada and am nervous about whether Home Depot's offering will do the job.

                            I'm pretty sure there's some theory I'm missing here guys! Can anyone help?
                            Last edited by jim_in_calgary; 01-11-2010, 07:10 PM.

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                            • #15
                              Re: 220 V baseboard heater wiring

                              No, it will not be running on 120v.

                              A 240v circuit is a line-to-line circuit. You must have a neutral to have 120v. A 240v circuit has no neutral.

                              If you break one of the lines in a 240v circuit you no longer have line-to-line. You then have line-to-nothing.

                              See how that works?

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