What Happens When a Circuit Breaker Gets Too Hot? (Risks & Discussion)

A circuit breaker can overheat for many reasons, such as electrical overloading, faulty wiring, and a weak circuit breaker. But have you ever wondered what happens when a circuit breaker overheats?

Generally, the breaker will overheat when the current exceeds the circuit breaker’s rated value. If the heating process continues, the circuit breaker will reach its breaking point, and two things will happen.

  1. The circuit breaker will trip.
  2. The breaker will stop the current flow to the particular device.

I’ll go into more detail below.

Consequences of a “Too-Hot” Circuit Breaker

opened circuit breaker in zoom
Video | Shawn Davis

If you detect unusual heating in one of the circuit breakers, you might worry about your house’s safety. In truth, you should be. However, knowing what comes after this unusual heating will help you immensely.

Most often, due to electrical overloads or faulty wiring issues, the circuit breaker might heat up. If this heating process continues gradually, the breaker will break the circuit connection and stop the current flow to the particular device.

Because the circuit is disconnected, you don’t have to worry about any electrical fire or damaging your electrical appliances. This is an excellent safety feature for your home electrical system.

This circuit breaker disconnection is known as circuit breaker tripping. So, if you ever had to deal with a tripped breaker due to overheating, let the circuit breaker cool down first. Otherwise, it might trip again.

Quick Tip: Most often, when the temperature of the circuit breaker exceeds 140˚F, the breaker will trip.


How Can I Know if the Circuit Breaker is Too Hot?

There are a few ways to identify an overheated circuit breaker, and here are those methods.

Use a Thermometer

different brand of thermometers
Video | SimpleGhar

Using a thermometer is one of the best methods to check the temperature of a circuit breaker. But first, you should know about the circuit breaker’s surface temperature.

Surface Temperature

If you inspect a circuit breaker closely, you can detect the surface temperature for that particular circuit breaker. For instance, if a circuit breaker has a 140˚F surface temperature, that breaker will trip at the 140˚F mark.

Take the thermometer and check the temperature of the breaker. If the temperature exceeds the particular surface temperature, overheating is the cause of the tripping.

Sometimes, low-quality circuit breakers might trip without any overheating. So, it is wise to check the temperature.

Use a Thermal Scanner

Using a thermal scanner is another way to check the temperature of a circuit breaker. This method is far more advanced than using a thermometer.

Use Your Fingers

using index finger method to check if breaker is hot
Video | Shawn Davis

This is the third method, and it is a bit old-fashioned. But it will work. Use the rear side of your index finger for this. Check each breaker with your index finger and find out which breakers are hot.


Why Does a Breaker Trip Due to Heat?

Here are some of the most common reasons.

Electrical Overloads

This is the most common reason for breaker overheating. Electrical overload can send a higher current than the breaker’s rated value. When that happens, the circuit breaker will overheat and trip the breaker. The breaker should be exposed to 80% of its amperage (NEC’s 80% rule).

What is NEC’s 80% Rule?

NEC’s 80% rule states that a circuit breaker should only be exposed to 80% of its rated value. For instance, if you have a 20 amp breaker, that particular breaker should be continuously exposed to a 16 amp current.

But that doesn’t mean a 20 amp circuit breaker cannot handle 20 amps or more. In truth, a breaker can handle up to 130% (most of the time) of its rated value. But during this process, the breaker will heat up and eventually trip.

Follow the below example for a better understanding (assume you are using a 20 amp breaker).

Breaker tripping amperage = 20 amps × 130% = 26 amps

This means the 20 amp breaker will trip around the 26 amp mark (sometimes it might trip at 25 amp). And at 26 amp, the breaker temperature will exceed its surface temperature.

Important: Not every 20-amp breaker can handle 25 or 26 amps. Some 20-amp breakers might trip at 21 or 22 amps. Either way, you shouldn’t expose the breaker to 80% of its rated value. 

Weak Circuit Breaker

Not every circuit breaker has the same quality. And some circuit breakers might weaken over time. When that happens, the breaker won’t be able to handle the current as usual. For instance, a weakened 20-amp breaker might overheat at 10 or 15 amps, and this could lead to tripping.

using multimeter to check breaker
Video | Electrician U

So, if you suspect the same thing is happening inside your electrical panel, take a clamp multimeter and measure the amperage of the circuit breaker while it is on. This will give you an indication of the circuit breaker’s capacity. If the capacity is below the rated value, replace the weakened breaker as soon as possible.

Short Circuit or Faulty Wiring

A short circuit situation can be a reason for circuit breaker trips. Also, damaged or incorrect wiring can be an issue too. 


FAQs

How to Identify a Tripped Circuit Breaker?

Suppose the circuit breaker switch is in the off position. That is an indication of a tripped breaker. You’ll also hear a “click” sound when the circuit breaker trips. Turn on the breaker switch to restore power to your home.

Can Summer Heat Cause a Circuit Breaker to Trip?

Summer heat can affect the overheating of the circuit breaker. But it won’t be the only reason. For instance, it will accelerate the heating process of an already hot circuit breaker.

Can I Use a Fan to Cool Overheated Circuit Breakers?

Yes, you can use a fan. But it won’t do any good. Remember, the circuit breaker is heating from the inside; hence cooling it from the outside won’t be effective. Instead, turn off the circuit breaker for a while. It will cool the circuit breaker.




Video References

MBJ DIY

Shawn Davis

Schneider Electric

SimpleGhar

BeachInfrared1

Electrician U

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About Sam Orlovsky

b1d87d2ee85af3e51479df87928bdc88?s=90&d=mm&r=gCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

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