An early form of circuit breaker was described by Thomas Edison in an 1879 patent application, although his commercial power distribution system used fuses.

Hugo Stotz, an engineer who had sold his company to Brown, Boveri & Cie, was credited as the inventor on German patent 458392.

[3] Stotz's invention was the forerunner of the modern thermal-magnetic breaker commonly used in household load centers to this day.

By 1935, the specially constructed circuit breakers used at the Boulder Dam project used eight series breaks and pressurized oil flow to interrupt faults of up to 2,500 MVA, in three AC cycles.

Circuit breakers for large currents or high voltages are usually arranged with protective relay pilot devices to sense a fault condition and to operate the opening mechanism.

A breaker may also use the higher current caused by the fault to separate the contacts, via thermal expansion or increased magnetic field.

This arc must be contained, cooled and extinguished in a controlled way, so that the gap between the contacts can again withstand the voltage in the circuit.

Different circuit breakers use vacuum, air, insulating gas, or oil as the medium the arc forms in.

Different techniques are used to extinguish the arc including: Finally, once the fault condition has been cleared, the contacts must again be closed to restore power to the interrupted circuit.

The number of plates in the arc chute is dependent on the short-circuit rating and nominal voltage of the circuit breaker.

Circuit breakers are usually able to terminate all current very quickly: typically the arc is extinguished between 30 and 150 ms after the mechanism has been tripped, depending upon age and construction of the device.

Typical domestic panel circuit breakers are rated to interrupt 6 kA (6000 A) short-circuit current.

For example, standard C37.16 lists preferred frame size current ratings for power circuit breakers in the range of 600 to 5000 amperes.

For medium- and high-voltage circuit breakers used in switchgear, substations and generating stations, relatively few standard frame sizes are generally manufactured.

These circuit breakers are often installed in draw-out enclosures that allow removal and interchange without dismantling the switchgear.

Large low-voltage molded-case and power circuit breakers may have electric motor operators so they can open and close under remote control.

The DIN-rail-mounted thermal-magnetic miniature circuit breaker is the most common style in modern domestic consumer units and commercial electrical distribution boards throughout Europe.

[7] Solid-state circuit breakers have been developed for medium-voltage DC power and can use silicon carbide transistors or integrated gate-commutated thyristors (IGCTs) for switching.

A thermal–magnetic circuit breaker, which is the type found in most distribution boards in Europe and countries with a similar wiring arrangement, incorporates both techniques with the electromagnet responding instantaneously to large surges in current (such as short circuits) and the bimetallic strip responding to lesser but longer-term over-current conditions.

Short-circuit currents provide sufficient solenoid force to release the latch regardless of core position thus bypassing the delay feature.

This is a very common requirement for three-phase systems, where breaking may be either three- or four-pole (solid or switched neutral).

Some makers make ganging kits to allow groups of single-phase breakers to be interlinked as required.

Two-pole common-trip breakers are common on 120/240-volt systems where 240 volt loads (including major appliances or further distribution boards) span the two live wires.

A shunt-trip unit appears similar to a normal breaker and the moving actuators are ganged to a normal breaker mechanism to operate together in a similar way, but the shunt trip is a solenoid intended to be operated by an external constant-voltage signal, rather than a current, commonly the local mains voltage or   DC.

These are often used to cut the power when a high-risk event occurs, such as a fire or flood alarm, or another electrical condition, such as over-voltage detection.

Medium-voltage circuit breakers rated between 1 and 72 kV may be assembled into metal-enclosed switchgear line-ups for indoor use or may be individual components installed outdoors in a substation.

It presents a technical solution where the disconnecting function is integrated in the breaking chamber, eliminating the need for separate disconnectors.

Implementing a DCB solution also reduces the space requirements within the substation, and increases the reliability, due to the lack of separate disconnectors.

[21] In 2012, ABB presented a 75 kV high-voltage breaker that uses carbon dioxide as the medium to extinguish the arc.

These devices under research and testing would have wireless capability to monitor the electrical usage in a house via a smartphone app or other means.