Understanding Electrical Safety Equipment: The Home Circuit Breaker

What's the most important safety feature in your home?

Your first aid kit? Fire extinguisher? Perhaps even your home insurance plan?

These are all good guesses, but like most safety equipment, they are reactive rather than proactive. They help homeowners respond to emergencies, not prevent them.

The circuit breaker, however, is the first line of defense towards preventing electrical accidents – one of the most common causes of home fires and workplace injuries in the United States.

Most electrical accidents can be prevented with a greater understanding of basic electrical safety principles and the tools that put those principles into practice. Of these, electrical breakers are the most useful (and often least understood) safety feature in the average home.

We're going to cover circuit breaker technology from the ground up, so read on to find out how you can check your old circuit breakers for damage, replace faulty ones, and identify major circuit breaker types.

What Do Circuit Breakers Do Exactly?

It's common knowledge that if a part of your home or workplace suddenly goes dark, you might be able to address the problem by tripping the corresponding circuit breaker. But how does that process work?

When electricity flows from your local power plant to your property, it goes through an electrical panel first. That panel separates your property's power grid into separate circuits – typically organized by room or by the type of appliances being powered.

Your building cannot draw an infinite amount of electricity from the local power grid. Each circuit has a maximum load that it can physically carry before becoming dangerous.

Electrical load refers to any device that draws power ­– your home's lights and appliances are all examples of loads.

Electrical CIrcuit Breaker Load

"An electrical load is an electrical component or portion of a circuit that consumes electric power."

Electrical engineers install circuit breakers to prevent you from accidentally drawing an unsafe electrical load from your municipal grid. When the load approaches a critical point, the breaker trips, cutting off the flow of electricity through the circuit, and preventing unsafe levels of power consumption from occurring.

What's the Difference Between a Circuit Breaker and a Fuse?

If your home was built in the 1960s or earlier, your electrical panel might not have circuit breakers at all, but fuses. Electrical safety can also be achieved with fuses, although modern fuses are typically installed on appliances – not on residential, commercial, or industrial electrical panels.

Fuses achieve the same result as circuit breakers ­ – preventing the flow of electricity in unsafe conditions – but do so in a different way. Fuses incorporate a small piece of metal that melts when exposed to unsafe levels of electricity, while circuit breakers simply operate a mechanism that can be reset afterward.

A fuse needs to be replaced every time it blows. A circuit breaker, on the other hand, can usually be reset manually.

The Difference Between a Generic Circuit Breaker and a Fuse

How to Identify Different Types of Circuit Breakers

There are three major types of consumer electrical breakers on the market:

Circuit Breaker Types

Three Major Types of Circuit Breakers:

  • Standard Breakers
  • Ground Fault Circuit Interrupter (GFCI) Circuit Breakers
  • Arc Fault Circuit Interrupter (AFCI) Circuit Breakers
  • Standard Breakers – The simplest type of breaker. Both single-pole and double-pole varieties exist.
  • Ground Fault Circuit Interrupter (GFCI) Circuit Breakers – Generally used in areas exposed to water to prevent electric shock.
  • Arc Fault Circuit Interrupter (AFCI) Circuit Breakers – Often used in conjunction with old wiring systems to prevent electrical fires.

In addition to these, industrial and municipal energy concerns also use specialized high-voltage varieties such as live tank and dead tank Siemens circuit breakers. These follow the same principles as a generic household power breaker, but with enormously increased load and safety considerations.

Standard Circuit Breakers

Standard breakers, made by almost all circuit breaker manufacturers, come in either single-pole or double-pole varieties. Single-pole breakers are the most common in most households – they are sufficient for most residential electrical loads.

Double-pole breakers are easy to identify because they occupy two slots on your household circuit breaker panel. These are designed for use with devices that carry a greater electrical draw, such as water heaters, kitchen appliances, and commercial equipment.

Ground Fault Circuit Interrupter (GFCI) Circuit Breakers

In addition to protecting against overloads of current, GFCI breakers also protect against an electrical phenomenon called line-to-ground fault. This occurs when an electrical path between the established current and a grounded element forms.

The main way to tell the difference between a standard breaker and a GFCI breaker is by noticing a small Test button and an On/Off Switch. They are most often used in areas that are exposed to damp conditions, as water conducts electricity and can cause a line-to-ground fault.

These types of circuit breakers are not recommended for use with appliances that must run all the time, such as refrigerators or computer servers. The extra protection can cause them to trip more often than needed.

Arc Fault Circuit Interrupter Circuit Breakers

Like GFCIs, these breakers feature a Test button, but they are designed to protect against a different type of dangerous electrical phenomenon: the arc flash.

Types of Electric Arcs

The four types of electric arcs are:

  1. Open-Air Arc (this is the primary arc used in arc testing
  2. Arc-in-a-Box (this is used in one form for arc testing in the EU)
  3. Ejected Arc (when arc plasma hits the electrician)
  4. Tracking Arc (most common at higher voltages, arc plasma conducts on skin or through clothing)


Arc flashes are spectacular discharges of electricity that are not yet fully understood by electromagnetic physicists. However, they are very dangerous and often the root cause of destructive electrical fires. Most circuit breaker manufacturers make AFCI breakers for high voltage and industrial conditions.

How to Test Used Circuit Breakers

Now that we've covered the types of breakers you're likely to find in your home or workplace circuit breaker panel, it's time to troubleshoot used circuit breakers.

Whenever observing old circuit breakers, look out for signs of damage such as:

  • Rust
  • Corrosion
  • Burning smells
  • Evidence of burnout
  • Signs of physical damage

If you have a breaker that seems to trip itself consistently, regardless of how your appliances and devices are plugged in, it could mean you have a faulty breaker. There are several ways to troubleshoot these devices, almost all of which require specialized tools.

Clamping Ammeter

Clamping Ammeter

These device determines whether your circuit breaker is overloaded or not. If a circuit breaker trips every time it is reset, using this device can help determine the source of the overload.

To use it, clamp the instrument onto a single wire and test the breaker with various appliances plugged into the circuit. You should be able to determine which appliance is overloading the circuit.



The multimeter is an electrical testing device that's easy for homeowners to use. Just touch one prong to each of the circuit's parts (the two holes in an electrical outlet, for example) to determine how much voltage is present in the circuit, how much current is being drawn, or the resistance of the current.

Comparing these values to local standards allows you to pinpoint the nature of the problem before conducting circuit breaker replacement.

How Can I Replace a Used Circuit Breaker?

If testing determines that the circuit breaker is faulty, you'll need to find compatible new or used breakers for sale. Circuit breakers are not generally interchangeable between manufacturers, so pay attention to the type, model, and brand of breaker you are looking to replace.

Typically, your circuit breaker panel is designed to work with the specific breakers installed, to the exclusion of all others. This is reflected in the technical specifications of various used circuit breakers and in their sizes – Square D circuit breakers are made not to fit in panels designed for older Westinghouse breakers, for example.

For many electricians and owners of older homes, this creates a difficult problem — finding a reliable provider of old or obsolete circuit breakers. If replacing the entire panel is out of the question due to time or financial constraints, then the only option is finding old circuit breakers that match the original models used when the structure was built.

Additionally, the replacement circuit breakers must feature the same voltage and amperage specifications. Furthermore, even breakers with the same specifications can be non-compatible if they are not both GFCI or AFCI breakers.

Fortunately, you can get all of the circuit breakers you need from Circuit Breaker Wholesale – we even carry old and obsolete breakers specifically for homeowners and electricians who need hard-to-find products.

How To Replace a Circuit Breaker

Replacing Faulty Circuit Breakers

Once you've determined that you have a defective circuit breaker in your home panel and found a compatible unit to replace it with, you're ready to replace the breaker by following these steps:

  • Turn off the main power supply – Every electrical panel has a main breaker switch that you'll need to flip before working on your panel. In some cases, this main switch is located on a different panel, located elsewhere on the property than your personal panel.
  • Test the panel with a multimeter – Even if you shut off the main power to your panel, a fault in that system could mean that electric current is still running. Always test panel components for the presence of electrical current before touching them.

Testing Circuit Breakers

"Always test panel components for the presence of electrical current before touching them."

  • Inspect your panel for unused breaker slots – If your panel has unused slots, you can install your new replacement breaker in the unused slot before removing the faulty one. You will be labelling this new breaker, so there is no need for it to be in the same exact location as the old one. 

Consult with the panel cover to determine whether there are provisions concerning exposing and replacing circuit breakers. Typically, you'll find metal twist-out slots for doing this. If you see none, install the new breaker on a different, unused slot.

  • Double check your circuit breaker – A single-pole breaker is suitable for a 120-volt circuit and a double-pole breaker is suitable for a 240-volt circuit. The amp-rating of the breaker should not exceed the circuit conductor's rating: usually 15 amps for 14-gauge copper, 20 amps for 12-gauge copper and 30 amps for 10-gauge copper.
  • Locate the breaker's mounting contacts – The replacement breaker will have two mounting contacts near its bottom. One of these is the mechanical mount for the breaker shell and the other is the electrical contact. Engage the non-electrical contact point first, and then gently push down the shell so that the electrical mounting component makes contact with the panel.
  • Set the circuit breaker to the OFF position – For safety reasons, you want the circuit breaker to be OFF when you prepare to engage the main power switch.
  • Align the new circuit breaker with the unused space on the panel – Tilt the breaker so that the non-electrical mounting point integrates with the panel's structure. You may now pivot the breaker and roll it towards the center of the panel before seating it in an unused location.
  • Connect the new circuit – Remove the old circuit breaker's connections and connect them to the new breaker terminal's ground and neutral mounting points. Clean up any foreign debris that could cause a short circuit.
  • Replace the cover and test – Make sure that the newly installed breaker is seated comfortably. Replace the panel cover and engage the main breaker switch. Now engage the newly replaced circuit breaker. If it works without tripping, label the new slot – you're done!

Looking for hard-to-find electrical components? Circuit Breaker Wholesale carries residential, commercial and industrial circuit breakers of all kinds, including old and obsolete models. Contact us to find the exact model you need! 

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