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What is a Circuit Breaker and What Causes Breakers to Go Bad?

Circuit breakers

An electrical circuit breaker allows circuits to be protected in the event of an overload or short circuit. There are some causes for breakers to go bad, such as long-term overloads, spikes in voltage, and short circuits.

In this article, you will learn the significant causes of breaker failure. Before replacing a faulty breaker, you have to check what caused the failure.

Why are Circuit Breakers Used?

Electrical circuits are protected from extreme currents using circuit breakers. A circuit breaker is an automatic switch designed to keep electrical systems safe.

When the circuit breaker detects any faults, it will stop the current flow, thereby protecting the power supply. Circuit breakers are rated for a specific voltage and current. For example, a residential circuit breaker is sold for 120 Volts and may be rated for 20 Amps. This means the circuit it is used on will be protected for any usage over 20 Amps. A short circuit or prolonged usage over 20 Amps will cause the breaker to trip. Commercial circuit breakers are usually for much higher currents and may protect single or three phase circuits.

Standard circuit breakers only protect on overloads, but newer breakers can combine overload protection with ground fault interruptions (GFCI) and arc fault interruptions (AFCI). We've covered these new dual fault current interruptors (DFCI) in a previous article, which cover the capabilities of GFCIs and AFCIs into one device, doubling the protection against shocks and fires.

What Causes a Circuit Breaker to Go Bad?

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Circuit breakers are used in residential, commercial, and industrial buildings to protect electrical circuits. Especially when regularly exposed to overload situations, a circuit breaker will suffer from an early demise.

To help our electrical technicians out there, we're here with a list of possible reasons that may cause a circuit breaker to go bad.

Power Surges and Spikes

In general, technicians assume that overloads and short circuits are the only causes of a circuit breaker to fail. But, there are other reasons as well, such as power surges and spikes. Electrical circuit breakers are affected by Voltage and power surges and spikes, a common occurrence in electronic components, also causing failure.

The threat of failure can be minimized when electrical panels are equipped with surge suppressors. However, this does not eliminate failure completely.

Overloaded Circuit

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Let's use a standard circuit breaker designed for 15 amps and 120 volts. The end-user is using it for three appliances rated at 1500 Watts, for a total of 4500 Watts. Using Ohms law, we can calculate that this 4500 Watts is equal to 37.5 Amps (4500 divided by 120).

The overloading of the circuit will result in a tripped breaker since the circuit is being used for 37.5 Amps, well over the designed maximum load of the breaker.

Before resetting a breaker, always verify what is connected to the circuit and what the ratings are for the equipment. If the equipment is within the maximum allowable current, then check for other failures.

It is a good idea to check whether a customer is overloading a circuit breaker when they complain about circuit breaker failure. Use a clamp meter to measure the current being used on the circuit. When regularly overloaded, the customer will either have to spread out the load onto multiple circuits or upgrade the breaker to a higher capacity.

However, before upgrading a circuit breaker, always ensure the wiring and power outlets on the circuit are rated for the higher current draw. Simply upgrading the breaker could be a recipe for disaster.

Short Circuit

Short circuits are one of the leading causes of circuit breakers to fail. Now, what are the causes of a short circuit? A short is just that – the current finds a shorter way from live/hot to neutral, bypassing the load entirely. So, instead of having current go through a motor or heating element, it finds a path around them. This short circuit draws a huge amount of current, immediately tripping the breaker. The breaker does what it is designed to do, interrupting the flow of electrons, before the short circuit damages wiring and other equipment.

Therefore, if you receive a complaint about circuit breaker failure, you must check for a short circuit. Use your multimeter for this, checking all the possible connected appliances. Do not simply use “try and fail” here – simply turning on the breaker and seeing which appliances trip the breaker is a sure way to damage equipment or even create a fire in the circuit wiring.

Bad or Faulty Wiring, Loose Connections

Even something as simple as a loose connector can cause a circuit to overload. Always ensure wires are tightly connected to the breaker and check for similar connection errors on all connected appliances. Loose wires can also cause arcing in circuits. For high amp equipment, check that wires are tightened to the manufacturer specified torque. Insulated torque screwdrivers have been designed specifically for this purpose.


How do you know if a circuit breaker needs to be replaced?

Unless it's malfunctioning or the wires are damaged, it does not need to be replaced unless you see it is burned or if it is hot to touch. You don't have to replace the breaker every time. Even just turning the breaker on and off can be a good indicator of its condition, often you'll feel a “sticky” handle or a handle that doesn't want to stay in its on position. When in doubt as to the condition of the breaker, it is usually recommended to replace it.

Typically, it is not necessary to replace or change the breaker if it trips, but repeated overload situations or a breaker that randomly trips can be other indicators for replacement. Before resetting the breaker, always ensure the fault that caused the trip has been rectified.

Is it common for a circuit breaker to go bad?

Circuit breakers

Yes, it can definitely happen; a breaker can stop working over time, usually caused by arcing of the contacts when the circuit is disconnected. Customers sometimes use a circuit breaker as a switch and disconnecting a circuit under load causes arcing of the contacts, which will greatly reduce the lifespan of the breaker.

It is essential to check them properly and make a decision whether to replace them or maintain them. Proper tests of the circuit and its loads will prevent the circuit breakers from going bad.

If a circuit breaker does go bad, the only option is to replace it – circuit breakers are not user serviceable and are usually sealed, preventing users from opening them.

What is the lifespan of a circuit breaker?

Circuit breakers generally do not have an exact life span. The CPSC estimates the product will last up to 40 years if it is in good condition and is properly maintained. In GFCI, AFCI and standard breakers, the lifespan ranges from 10 to 15 years. 

Humid environments shorten their lifespans while moderate climates or dry environments prolong them. Breakers that regularly trip from overloads or breakers that have been pushed beyond their design specifications may only last a few years.