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I want to run a 220 volt circuit from panel to an electric fireplace (12 amps) and an electric heater (15 amps). What size breaker should I use and what size wire?

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  • Are you talking about putting them both on the same breaker?
    – Kellenjb
    Jan 23, 2012 at 20:23
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    By the sounds of it, you want one breaker/wire for both. To provide the best answer: What is the distance between the panel and the fireplace? Panel and heater? What's the total distance if you did one run from the panel to fireplace to heater (or whatever way makes most sense)? It may or may not be cheaper to run two separate (smaller) wires (eg #12 or #14) rather than a single circuit on eg. #10, the distances will help us provide answers for both scenarios and you can decide depending on local pricing.
    – gregmac
    Jan 23, 2012 at 20:24
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    Are these your two primary heating sources? If so you might opt to put them on two breakers so that if one trips you don't risk having no heat at all!
    – Steven
    Jan 23, 2012 at 22:06
  • Distance is approximately 25 ft from breaker to furtherest heater approx 15 ft to fireplace. They are not primary heat sources.
    – Hal
    Jan 24, 2012 at 0:24

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10 gauge wire is the largest I like to use in home use. Depending on who you talk to and what code book you are looking at, the amount of current a 10 gauge wire can handle changes. I tend to think it can safely handle about a 30 amp breaker (and I think most code books fall in line with this).

You can add up the amps (12+15=27 amps) to get the total amps possible. This would mean that a 30 amp breaker with 10 gauge wire should work fine. However, check your currents to make sure that is the max that will be pulled. Many items have a large start up current that can cause a breaker to trip if you aren't careful.

For things that pull this much current by themselves, it is generally better to split them into 2 different breakers. So for you I would go with a 15 amp and a 20 amp. Technically you can use #14 on the 15 amp breaker, but if it were me I would go ahead and run #12 in case you some day want to swap out your fireplace with something that pulls more power.

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  • Using one circuit, could 10/2 be used to the fireplace and then continue with 12/2 to the furtherest heater?
    – Hal
    Jan 24, 2012 at 0:32
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    This setup really is not recommend because the circuit breaker is designed to protect everything down from it. Think about a situation where the fireplace is turned off and the heater malfunction causing 25 amps to be pulled, all of that current is flowing through a now over powered cable that will heat up and could eventually start a fire.
    – Kellenjb
    Jan 24, 2012 at 0:37
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    I don't get the comment: "10 gauge wire is the largest I like to use in home use."......What do you use to wire a range? How about a welder? Steam generator? Spa? A/C condensor?
    – Speedy Petey
    Oct 22, 2014 at 20:58
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add them together for at least 27 amps (for a 30 amps circuit)

split the circuit in a 15 for the 12 amps fireplace and a 20 for the 15 amps heater (to avoid the breaker tripping on the startup spike)

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  • There's no startup spike with resistive loads like heaters.
    – gregmac
    Jan 24, 2012 at 0:57
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    @gregmac unless there is a fan on the heater
    – Kellenjb
    Jan 24, 2012 at 1:10
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    @Kellenjb, even then the "startup spike" would be negligible.
    – Speedy Petey
    Oct 22, 2014 at 20:56
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People thinking like this is exactly what keep us electricians in business.Run a separate circuit too each appliance using #12 on a 20 amp circuit breaker. If you are not qualified to do electrical work please use a licensed electrician in your area so you do not cause a hazard and risk of fire. You don't just add up the amperage or wattage, that's not the way calculations are done. Another misgiving we see from time to time is if it trips the breaker put a larger size breaker on it., that is asking for a fire if you over breaker a wire with a larger size than the wire gauge is rated for.

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  • Can you give us a citation or reference for "You don't just add up the amperage or wattage?"
    – ThreePhaseEel
    Feb 10, 2017 at 23:19

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