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220 Volt Electric Furnace Wiring

   
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How to Connect the Electrical Circuit Wiring for a Furnace – The designation L normally means Line which usually has a hot from the circuit attached, not a neutral.


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Electrical Question: I have installed an electric furnace with a 15 kw heat element.

  • I ran number 6 wire with ground from my 100 amp service box where I installed a 60amp double pole breaker.
  • The furnace comes with an other set of breakers one 60amp and one 30amp where I am supposed to connect the line voltage.
  • I put the red wire in L1 the black wire in L2 and the white wire in L3 and the ground on the ground screw.
  • What goes in L4?
  • The blower comes on but no heat.

This electrical wiring question came from: Tony, a Handyman from Bloomfield, New Mexico
Additional Comments: Good Questions and Good Answers

Dave’s Reply:
Thanks for your electrical wiring question Tony.

How to Connect the Electrical Circuit Wiring for a Furnace

Skill Level: Intermediate to Advanced.
Tools Required: Basic Electricians Pouch Hand Tools, electric drill, auger bits and extension cord.
Estimated Time: Depends on personal level experience, ability to work with tools and install electrical circuit wiring.
Notice: Installing additional furnace wiring should be done with a permit and be inspected.

  • When wiring a furnace you need to check the wiring instructions for the units and the incoming circuits.
  • The designation L normally means Line which usually has a hot from the circuit attached, not a neutral.
  • Due to a lack of information about this unit I can only provide limited information.

Wiring Connections for 220 Volt Electric Heater

  • Identify the Voltage
    • 208 Volt and 220 Volt Connections Wiring connections may need to changed depending on the voltage of the unit and the voltage at the location where the unit will be installed.
  • Electric Furnace Heating Elements and Heat Strips

    • The electrical circuit for an electric furnace will depend on the number and watt or kw size of the electric heating elements
    • In some cases, due to the electrical requirements,  it may be necessary to install a separate dedicated circuit just for the heating elements or heating strips.
  • Furnace Blower Motor Speed
    • Many furnace blower motors may be adjusted depending on the size of the home.
    • Confirm the proper speed setting and adjust the wiring connections at the wire terminal strip, or adjust the wire splices to the motor leads.
    • Unused wire leads must be capped off or relocated as instructed by the installation manual.

Electric Furnace Manual

Example of an Electric Furnace Wiring Diagram

electric furnace wiring diagram
Electrical Circuit Wiring for an Electric Furnace

2-pole-circuit-breaker

220 Volt Wiring Diagram

  • Wiring 220 Volt Electrical Outlet
    • Home electrical wiring includes 110 volt outlets and 220 volt outlets and receptacles which are common place in every home. See how electrical outlets for the home are wired.

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Comments

12 Responses to “220 Volt Electric Furnace Wiring”
  1. Hubert says:

    I have a new York electric furnace and to wire it up for 220 volt I only see L1 and L2, that are the black and red wires. I also hooked up the ground wire.
    But, in my cat 3 wire (required), there’s also a white neutral wire that as no place for it to be connected in the furnace.
    There is a 2nd ground screw in the furnace where I can hook a ground to, so I am wondering if I can hook the white (neutral) wire to the 2nd Ground screw in the furnace ? Or should I leave the white (neutral) wire unplugged with the pigtail? Thanks.

    • Dave Rongey says:

      Hi Hubert,
      The cat 3 wire that you are describing has nothing to do with the circuit power which is required for the electric furnace. In this case, the cat 3 cable may be intended for the thermostat and the control process of the furnace unit.
      The electrical circuit requirement(s) will specifically state if the unit requires a 3-wire or 4-wire circuit, and if the circuit requires a dedicated neutral wire, and if so then there will be a termination point provided specifically for the neutral wire. If your circuit wiring has a spare white neutral wire and your furnace specifications does not require a neutral wire then cap off the white neutral wire as a spare wire and do not attach it to the ground terminal. With equipment such as this ground terminals are for ground wires only. Please consult your electric furnace Installation Manual for specific detailed instructions.
      I hope this helps you,
      Dave

  2. paul says:

    I have installed a GE electric furnace which has two 220 volt circuit beakers in the front section. Are both of these circuit breakers only for the heating coils? The blower motor just turns really slow and the coils will not heat up.

    • Dave Rongey says:

      Hi Paul,
      This would depend on the exact model electric furnace you have. If the heating coils are large, then they may require separate circuit breakers. Keep in mind that the power for blower motor for the furnace is most likely provided from a separate circuit or receptacle. If the blower is not powered, and there is no air flow through the unit then the heating coils will not heat up. The heating coils will be controlled by safety devices such as high temp switches and air flow switches. For complete information consult the installation manual or owners manual for your specific electric furnace unit.
      I hope this helps you,
      Dave

  3. richard lee says:

    We installed a new furnace with a Duroguard electric heat kit. I am having problem with the wiring. The air kicks on but there is no heat. What do you suggest? It is all new, and there is a new Honeywell thermostat.

    • Dave Rongey says:

      Hi Richard,
      Double check the connections to the thermostat as compared to the furnace and the electric heat kit. It sounds like the thermostat is wired so the blower is being told to start instead of the heating unit. The thermostat should have a manual switch for the blower and the heat setting for the furnace. The wiring for these two functions may need to be reversed. You may be able to reference the old thermostat for the wiring configurations as well.
      Dave

  4. lisa says:

    I need the wiring schematics to wire a Coleman Tappan Speedmatic Model 731 Electric Furnace.

  5. RICK says:

    HAVE AN OLD MCRA 2315 INTERTHERM ELECTRIC FURNACE I AM PUTTING IN MY GARAGE. WHEN I CONNECT THE POWER TO IT 240 VOLT USING #6 WIRE I HAVE THE FOLLOWING PROBLEM. IT CONNECTS INTO A FUSE BLOCK WITH TWO 30 AMP AND TWO 60 AMP FUSES. I HOOK THE 2 LEADS TO THE MAIN LUGS AND 1 GROUND. WHEN I TURN IT ON THE FAN COMES ON AND RUNS GREAT BUT THE COILS WONT ENERGIZE I CAN UNHOOK THE BLOWER MOTOR AND 1 SET OF COILS WILL COME ON AND START CYCLING. HOOK THE FAN BACK UP AND THEY GO OUT. ANY IDEAS?

    • Dave Rongey says:

      Rick,
      I would look for a control circuit that may be starting the fan first then a circuit that would start and stop the heating coils. You may be attempting to wire the furnace direct, but instead you may need to wire in a control circuit. Basically something has to regulate and control the heating coils properly. With a typical furnace a thermostat sends control voltage which starts the unit, the fan starts, a sensor checks to make sure there is air flow, then if there is air flow the heating source is activated. The same process in reverse basically occurs after the desired temp is reached. The point is to not activate the coils unless there is air flow, and to make sure the unit is cooled off even after the heat has stopped.
      Look for the control circuit wiring diagram which should basically show a control circuit loop, where the control circuit is provided from a transformer or power supply.
      This should help get you going.
      Dave

  6. Alex Leclerq says:

    I was thinking about buying a Coleman electric furnace but I’m not too sure these instructions would be compatible.

    • Dave Rongey says:

      Hi Alex,
      The instructions on this page about 220 volt furnace wiring may apply if the Coleman furnace you are referring to has the same specifications. Consult the installation manual which comes with the furnace to be sure of the circuit requirements and the wiring connections.
      Dave

  7. Glenn says:

    I have a Dayton 2yu58 Electric heater.This unit can run on 208v or 240v. I have 220.What do I do?
    The specs on the unit say it requires 12 amps.The unit itself says it requires .25 amps(is that a misprint maybe?)
    The unit installation instructions say I only need 5/16 threaded rod to mount and install the unit. Does this mean I can wire it directly to the line voltage?
    I am wiring it for single-phase operation.

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