Circuit Breakers Electrical Supplies Unlimited is your go-to source for Circuit Breaker electrical supplies in San Diego and surrounding areas. We have a large inventory of most brands of circuit breakers including new, used, refurbished, recycled and obsolete breakers. We carry a large variety of manufacturers, including Zinsco, Federal Pacific FPE, Pushmatic, Bulldog, Cutler, Hammer, ITE Siemens, Square D etc. in our San Diego store. We carry most amperages and voltages. Some examples of what we carry:

20 Amp thru 125 amp Zinsco breakers
20 amp through 1200 amp 480 volt Siemens breakers 3 phase and single phase
15 thru 100 amp 120/240 Volt Pushmatic Breakers
15 thru 1200 amp 120/240 and 480V Federal Pacific FPE circuit breakers

We carry a large variety of manufacturers, including Zinsco, Federal Pacific FPE, Pushmatic, Bulldog, Cutler, Hammer, ITE Siemens, Square D etc. in our San Diego store.  We are circuit breakers and electrical hardware experts and have decaades of experience to help you. Do not hesitate to call us at 858.558.2850 to find out which Circuit Breaker is right for your requirement.

used circuit breaker sales San DiegoElectrical Supplies Unlimited is your company's business source for testing, repairing, rebuilding or reconditioning electrical equipment. ESU maintains a wide variety of out of stock circuit breakers, relays, transformers, switches, relays, motor controls, and other electrical equipment. ESU will also purchase your excess electrical inventory. We buy obsolete circuit breakers, new and used, transformers, fuses. Call us today to find out more!

A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city.

Electrical Supplies Unlimited supplies a large stock of new and used Low Voltage Circuit Breakers (600 Volts) and Medium Voltage Circuit Breakers (5-27kV).

We stock the following manufacturers products and can either buy or sell the circuit breaker in question:

Low Voltage Breakers

Federal Pacific
Square D
Roller Smith
GE - General Electric
Westinghouse-Cutler-Hammer
Siemens-Allis Chalmers
ABB-BBC-ITE-Gould


Medium Voltage Breakers

GE
Westinghouse-Cutler-Hammer
Siemens-Allis Chalmers
ABB-BBC-ITE-Gould
Federal Pacific
Square D

Circuit breakers are electrical switches designed to protect an electrical circuit from damage caused by overload or short circuit.
If a circumstance arises where a fault condition occurs, the switch discontinues electrical flow. This circuit breaker can be reset either manually or automatically. In contrast, a fuse must be replaced when it operates one time.

Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear
designed to protect high voltage circuits feeding an entire city.

Types of Circuit Breakers

Low voltage circuit breakers
Magnetic circuit breakers
Thermal magnetic circuit breakers
Common trip breakers
Medium-voltage circuit breakers
High-voltage circuit breakers

Operation

All circuit breakers have common features in their operation, although details vary substantially depending on the voltage class, current rating and type of the circuit breaker.

The circuit breaker must detect a fault condition; in low-voltage circuit breakers this is usually done within the breaker enclosure. Circuit breakers for large currents or high voltages are usually arranged with pilot devices to sense a fault current and to operate the trip opening mechanism. The trip solenoid that releases the latch is usually energized by a separate battery, although some high-voltage circuit breakers are self-contained with current transformers, protection relays, and an internal control power source.

When an breaker is no longer produced new, you need to purchase a used or reconditioned one. There are a few things to look for when doing this. The breaker should attach and hold snugly to the buss after it is attached, and you should feel some resistance as you push it onto the buss. The bare metal at the point where the breaker attaches to the buss should appear in good condition without burned areas where it has overheated or arced. The plastic around this point should appear the same as the plastic on the rest of the breaker, not discolored or misshaped from overheating.

At ESU, Inc. we stock all kinds of obsolete circuit breakers and only sell those of quality. Check out our guarantee then give us a call!

The simplest circuit protection device is the fuse. A fuse is just a thin wire, enclosed in a casing, that plugs into the circuit. When a circuit is closed, all charge flows through the fuse wire -- the fuse experiences the same current as any other point along the circuit. The fuse is designed to disintegrate when it heats up above a certain level -- if the current climbs too high, it burns up the wire. Destroying the fuse opens the circuit before the excess current can damage the building wiring.

The problem with fuses is they only work once. Every time you blow a fuse, you have to replace it with a new one. A circuit breaker does the same thing as a fuse -- it opens a circuit as soon as current climbs to unsafe levels -- but you can use it over and over again.

The basic circuit breaker consists of a simple switch, connected to either a bimetallic strip or an electromagnet. The diagram below shows a typical electromagnet design.