Electric Furnace Amps, Watts & Breaker Size
A 15 kW heat kit is about 60 to 63 A and 15,000 W behind a 60 A breaker; a 20 kW kit is 80 to 83 A and 20,000 W behind 80 A. These are among the largest loads a house can add, and the question is almost never the furnace — it is whether the panel and the service can carry it.
Electric Furnace Power Requirements at a Glance#
An electric furnace is one of the largest continuous loads a home can add, hardwired at 240 V with no receptacle anywhere. A 15 kW heat kit draws about 60 to 63 A for a connected load of 15,000 W on a 60 A breaker; a 20 kW kit draws 80 to 83 A and 20,000 W on 80 A, and the air handler is commonly fed by two large breakers wired together rather than one. At that scale the specification is the easy part of the conversation. The table below is the hard part.
Electric Furnace Electrical Specifications#
| Configuration | Voltage | Amps | Watts (max load) | Breaker | Outlet (NEMA) |
|---|---|---|---|---|---|
| Electric furnace with 15 kW heat kit | 240 V | 60–63 A | 15,000 W | 60 A | Hardwired |
| Electric furnace with 20 kW heat kit | 240 V | 80–83 A | 20,000 W | 80 A | Hardwired |
An electric furnace makes warmth with banks of resistance strips, the single largest continuous load a house can add, so its air handler is often fed by two big breakers wired together rather than one. Sizing follows the heat-kit rating stamped on the cabinet, and the strips usually stage on in steps to soften the inrush.
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What a load this size asks of your panel#
Every row here is answered before the furnace is ordered, not after it is delivered.
| The question | What decides it | Why it comes before the furnace |
|---|---|---|
| Is there panel space? | A 60 A or 80 A double-pole breaker, often two wired together | The air handler is commonly fed by more than one breaker, so what is needed is not a single spare slot |
| Will the service carry it? | The whole-house load calculation, not this appliance alone | At 15,000 to 20,000 W the heat kit can be the largest single load in the house; a service upgrade is a real possibility and it is priced separately |
| What size conductor? | The breaker rating — 60 A or 80 A — and the length of the run | This is the part of the job that cannot be estimated from a catalogue page, and it is where the cost lives |
| Where does it connect? | Hardwired, with no receptacle at any point | There is nothing to plug in and nothing to test by trying: every answer comes from the panel and the equipment nameplate |
| Do the heat strips all fire at once? | No — they stage on in steps | That staging is why the running draw and the breaker rating sit close together here, unlike a motor load that surges on starting |
Two heat-kit sizes are counted here, and both are large enough that the appliance is rarely the constraint. Figures come from manufacturer installation sheets; whether your service and panel can carry them is a whole-house load calculation, and nothing on this page can stand in for it.
Circuit and Breaker Sizing for the Electric Furnace#
The breaker on an electric furnace is sized to its resistance-strip rating, the single heaviest continuous load in the house. A 15 kW kit running near 60 A sits on a 60 A breaker, and a 20 kW kit near 80 A on an 80 A breaker, with the conductor sized to carry that rating across the run to the air handler. Because that load is so large, the air handler is commonly split across two big breakers wired in tandem instead of one enormous one, and the strips stage on in sequence to soften the inrush. This is unambiguously a dedicated circuit — often a dedicated pair — and nothing else may share it, least of all the cooling condenser, which draws its own current on a separate feed.
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Gas vs. Electric: How the Electric Furnace Wiring Differs#
The wiring contrast between the two furnace types is dramatic. An electric furnace makes heat with banks of resistance strips, which is why it demands that huge 240 V feed — 60 A for a 15 kW kit, 80 A for a 20 kW kit, at 15,000 to 20,000 W. A gas furnace burns fuel for heat and uses electricity only to run its blower motor, igniter and controls, so it lives happily on a modest 120 V circuit drawing a few amps. That is why a gas furnace is far cheaper to wire — no heavy 240 V line, no oversized breakers, no service-panel headroom worries — while the electric version can push a panel to its limit.
Installation and Safety Notes for Electric Furnace Wiring#
Installation is heavy hardwiring: the 240 V supply lands at the air handler and the conductors are matched to the 60 or 80 A breaker (or the tandem pair), with no cord or receptacle anywhere. This is firmly permitted-and-inspected work, and the inspector verifies the conductor size against the heat-kit rating, the breaker configuration, and whether the existing service panel can even carry the added continuous load. Sizing a 60 to 80 A resistive circuit and confirming panel capacity is squarely a licensed electrician’s job — an undersized conductor on a load this large is a genuine fire risk, not a nuisance-trip inconvenience.
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Electric Furnace Electrical FAQ#
What breaker does an electric furnace demand?#
A 15 kW heat kit needs a 60 A breaker at 240 V, and a 20 kW kit needs an 80 A breaker. The breaker is sized to the resistance-strip rating stamped on the cabinet, and the load is often split across a tandem pair.
Why is the air handler fed by two separate breakers?#
The heat-strip load is so large that splitting it across two big breakers wired together is easier to conductor and stage than one oversized breaker. The strips then energize in steps to soften the startup inrush.
How much current does a 15 kW heat kit pull?#
A 15 kW electric furnace heat kit draws about 60 to 63 A at 240 V, for a connected load of 15,000 W. That is why it sits on a 60 A breaker.
Can the furnace and the condenser share one circuit?#
No. The electric furnace is a very large dedicated load on its own feed, and the central air conditioner draws its own current on a separate dedicated circuit. Combining them would overload the conductors.
What conductor gauge feeds a 20 kW strip heater?#
The conductor is sized to carry the 80 A breaker of a 20 kW kit across the run to the air handler — a heavy gauge. An electrician sizes it to the breaker, the distance and the panel; this is not a place to estimate.
Is a fuel-burning furnace cheaper to wire than this?#
Considerably. A gas furnace runs on a modest 120 V circuit for its blower and controls, avoiding the 60 to 80 A / 240 V feed, the oversized breakers, and the service-panel capacity concerns of an electric furnace.
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