Air-Source Heat Pump Amps, Watts & Breaker Size
A 2 to 3-ton air-source heat pump runs at 15 to 20 A behind a 30 to 40 A breaker; a 4 to 5-ton unit runs at 25 to 30 A behind 45 to 60 A. The breaker is roughly double the running draw on purpose, and sizing a heat-pump circuit from the running amps is exactly how one ends up undersized.
Air-Source Heat Pump Power Requirements at a Glance#
An air-source heat pump runs on 240 V and is wired straight into a weatherproof disconnect, with no plug anywhere in the arrangement. A 2 to 3-ton model draws 15 to 20 A for 3,600 to 4,800 W behind a 30 to 40 A breaker; a 4 to 5-ton model climbs to 25 to 30 A and 6,000 to 7,200 W behind 45 to 60 A. Notice that the breaker in each row is roughly twice the running current — that gap is deliberate, and reading it as an error is the usual reason a heat-pump circuit gets specified wrong. The table below separates the numbers.
Air-Source Heat Pump Electrical Specifications#
| Configuration | Voltage | Amps | Watts (max load) | Breaker | Outlet (NEMA) |
|---|---|---|---|---|---|
| 2 to 3-ton air-source heat pump | 240 V | 15–20 A | 3,600–4,800 W | 30–40 A | Hardwired |
| 4 to 5-ton air-source heat pump | 240 V | 25–30 A | 6,000–7,200 W | 45–60 A | Hardwired |
An air-source heat pump is an outdoor condenser that both cools in summer and reverses to heat in winter, so it runs far more hours a year than a cooling-only unit and always sits on its own hardwired circuit at a weatherproof disconnect. Like any compressor load its breaker comes from the nameplate overcurrent figure, not the running amps.
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Reading a heat-pump circuit: four numbers that are not the same number#
Each row is quoted on a different document — the nameplate, the brochure, the panel schedule. They answer different questions.
| The number | What it describes | What it decides |
|---|---|---|
| 15–30 A running draw | What the compressor and fan pull once they are turning | Your running cost — and nothing else. It is not the figure the branch is sized from |
| 3,600–7,200 W | The same running load in watts, across both size classes | Comparison between models: it tracks the tonnage, not the breaker |
| 30–60 A breaker | What the branch is protected at | The conductor size and the panel space. It sits well above the running draw on purpose, so that a compressor starting is never read as a fault |
| Hardwired, no receptacle | How the unit connects | There is no plug to inspect and no cord to change — every question about this circuit is answered at the panel and at the disconnect |
| The outdoor disconnect | A weatherproof switch within sight of the unit | It is part of the installation rather than an accessory: a technician has to be able to kill the unit at the unit |
Two tonnage bands are counted above, and a heat pump is specified per model rather than per band. The nameplate on your own outdoor unit is what an electrician sizes the branch from — nothing here substitutes for that plate, and none of these figures should be used to re-breaker an existing circuit.
Circuit and Breaker Sizing for the Air-Source Heat Pump#
Copper is chosen from the minimum-circuit ampacity stamped on the condenser, so the smaller machine takes 10 or 8-gauge to its 30 to 40-amp breaker and the larger one 8 or 6-gauge to its 45 to 60-amp breaker. Notice the protection sits well above the 15 to 30-amp running figure: an inverter compressor throws a sharp surge as it spins up, and the label's maximum-overcurrent value already folds that in. Nothing else may ride this branch — the outdoor feed belongs to the unit alone.
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Dedicated Circuit and Disconnect for the Air-Source Heat Pump#
Every outdoor condenser earns a private branch plus a disconnect the technician can reach within sight of the machine, so power dies at the unit before anyone opens it. Since the same box heats through winter and cools through summer, it logs far more running hours than a cooling-only condenser, which is exactly why a reliable exclusive feed pays off. And rather than reading the running amps, the installer takes the maximum-overcurrent number off the data plate, because that stamped figure has already accounted for the locked-rotor jolt at start-up.
Installation and Safety Notes for Air-Source Heat Pump Wiring#
With no cord in play, the task is landing correctly sized copper on a two-pole breaker and bolting the disconnect beside the condenser. A fresh 240-volt run this large always draws a permit and an inspection, and the inspector cross-checks wire, breaker, and disconnect against the data plate. None of this is weekend territory: pulling a 45 to 60-amp outdoor circuit, then charging the refrigerant and proving the controls, is a job for a licensed electrician working with an HVAC installer.
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Air-Source Heat Pump Electrical FAQ#
What breaker does an air-source heat pump need?#
Expect a 30 to 40-amp two-pole breaker on a 2 to 3-ton unit and a 45 to 60-amp one on a 4 to 5-ton unit. The data plate, not the running amps, fixes the number.
How is a heat pump circuit different from an AC condenser?#
The sizing math is identical, but this box also heats in the cold months, so it works many more hours a year. That extra duty makes its private feed and cutoff switch matter even more.
Why is the breaker set by the nameplate, not the running amps?#
Because the stamped overcurrent figure already covers the compressor's spin-up surge, which dwarfs the steady draw for a moment. Size to the running amps alone and the breaker would pop on every start.
Does an outdoor heat pump need a service disconnect?#
Yes — a weatherproof cutoff has to sit where the technician can see it from the machine, so the circuit can be killed at the unit before any service.
How much current does a four-ton heat pump draw?#
A 4 to 5-ton model pulls 25 to 30 amps while running, for 6,000 to 7,200 watts. Its 45 to 60-amp breaker leaves headroom for the start-up spike.
Can the heat pump and the air handler share a circuit?#
They cannot. The outdoor condenser keeps its own branch while the indoor air handler is fed on a separate one; doubling them up would overload a single feed.
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