What is a double-pole breaker?
Updated August 2026
A double-pole breaker is a breaker that fills two slots in the panel, clamps onto both 120-volt hot bus legs, and delivers 240 volts to a single circuit. A metal tie joins its two handles, so a fault on either leg trips both together and the appliance goes fully dead instead of half dead. Ratings of 20, 30, 40, 50, and 60 amps cover almost everything a house needs at that voltage.
Where it is
Open the panel door and find the wide breakers, usually grouped near the top where the bus is fed. Each is the width of two standard breakers and carries one number, 30 or 50, printed across a joined handle. The panel directory beside them reads about the same in every house: electric range, clothes dryer, water heater, air conditioner condenser, well pump, EV charger, or a feeder out to a subpanel. The cable leaving a double-pole breaker holds two hot conductors, usually one black and one red, in 10/3, 8/3, or 6/3.
What it does
Two hot legs 180 degrees out of phase put 240 volts across the load, which halves the current for the same wattage: a 4,500-watt water heater element pulls about 19 amps at 240 volts instead of 38 at 120. Less current means smaller wire and less heat in the walls, which is why every large resistive load in a house is wired this way. Failure is usually asymmetric. One pole quits, the appliance still sees 120 volts, and the result is a machine that half works: the dryer tumbles without heating, the range burners light while the oven stays cold, the condenser hums and never starts. Repeated tripping is the other pattern, and it accuses the load or the wiring at least as often as the breaker, so read what makes a breaker trip before buying parts.
Maintenance
Exercise it once a year. Switch the breaker firmly off, then back on, which wipes the internal contacts and keeps a mechanism that has not moved in a decade from seizing. Do the whole panel in one pass on the annual breaker test, and note anything that feels warm through the cover or smells faintly of hot plastic. Breakers are cheap and long-lived, commonly 30 to 40 years in a dry panel, and the ones that die early almost always sat under a chronic overload or a loose lug.
What it costs to replace
A replacement double-pole breaker runs $10–40 for the breaker itself, or $150–350 installed, since most electricians bill a one-hour minimum.
OnOtto's photo scan identifies parts like this in your home and builds the maintenance schedule for you. See how the scan works.
Frequently asked questions
How do I know if a double-pole breaker has gone bad?
Measure it rather than guess. With the breaker on, a meter across its two load lugs should read about 240 volts, and each lug to neutral should read about 120. Read 120 across the pair and one pole is dead, the classic reason a dryer spins without heat. A breaker that trips the instant you reset it with the appliance unplugged has either an internal fault or a short on the circuit. Both readings are electrician work, because the panel bus stays energized with the main breaker off.
What size double-pole breaker does my appliance need?
The nameplate and the wire gauge decide, never the symptom. Common pairings: 30 amps on 10 AWG for an electric dryer or water heater, 40 to 50 amps on 8 or 6 AWG for a range, 20 to 30 amps for a condenser exactly as the sticker on the unit specifies, and 50 to 60 amps for a 40-amp or 48-amp EV charger, since continuous loads get sized at 125 percent. Fitting a larger breaker to stop nuisance tripping leaves the existing wire unprotected.
What is the difference between a double-pole breaker and a tandem breaker?
They solve opposite problems and only look alike in a photo. A tandem, also called a duplex or cheater breaker, packs two separate 120-volt circuits into one panel slot to buy space, and its two handles move independently. A double-pole spans two slots to build one 240-volt circuit, and its handles are tied so both open together. Every panel label states how many tandems the box accepts, and exceeding that count is a routine inspection failure.
Can I swap a double-pole breaker myself?
The part costs $10–40 and the job looks like two screws, which is the trap. The main lugs stay energized after the main breaker is off, and a slipped screwdriver there produces a 240-volt arc flash. Owners who insist on doing it should have the utility pull the meter or open an outside disconnect first, and should confirm zero volts with a meter rather than a tester. Paying an electrician $150–350 for twenty minutes of work is the ordinary call.