What Causes Your Arc Fault Breaker To Trip?


Arc Fault Breaker

The NEC building code has expanded the required use of arc fault breakers in recent years. While this improves the overall safety of a home against fires caused by electrical arcs, it’s not without its problems.

One of the routine problems we see in new construction homes is that arc fault breakers seem to trip for seemingly no reason. But is it really for no reason or an underlying problem that the arc fault breaker is trying to bring to your attention?

What causes your arc fault breaker to trip? Arc Fault Breakers (or AFCIs) are designed to monitor and trip in case of electric arcs to protect against electrical fires. Nuisance tripping (or tripping without any apparent reason) can occur due to improper wiring, incompatible electronic devices being plugged in the circuit, or in some cases older arc fault breakers can frequently trip due to them wearing out with time.

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However, AFCIs can be very sensitive sometimes, leading to frequent tripping and cutting out the power when for no apparent reason. However, is it really a nuisance tripping or a signal that another problem exists. We need to dig a little deeper understand why this is happening.

This frequent tripping can mean different things and should never be ignored as this can be a sign of a potential hazard. First, let’s identify what an arc fault circuit interrupter is.

What is an Arc Fault Circuit Interrupter (AFCI)?

An arc fault circuit interrupter (AFCI) is an advanced circuit breaker that breaks the circuit when it detects a dangerous electric arc in the circuit that it protects. This is a safety feature the NEC adopted in the late 1990s and has expanded over the years as updates and more data has been collected.

An AFCI has the capabilities to determine the difference between a harmless arc and a potentially dangerous arc. that can occur, such as in a lamp cord with a broken conductor. An AFCI is designed to detect a wide range of arcing electrical faults in order to reduce the risk of the electrical system being the source of a fire.

Harmless arcs can be defined as electrical arcs that occur when a switch is turned on or when an electrical device is turned on that is powered by an outlet such as a lamp.

Dangerous arcs can be defined as electrical arcs caused by damaged or loose wire connections, a faulty electronic device, or even nearby lightning strikes which cause an arc fault detected by the arc fault breaker.

So when should AFCIs trip? Here’s what we need to know in that case:

When Should AFCIs Trip?

Actually, it may seem like AFCI breakers do a very simple job, interestingly enough to do it properly and protect our homes, they are packing some serious digital electronics inside of them.

AFCIs or (Arc Fault Circuit Interrupters) has a very unique and important role when protecting our homes – they protect our homes from electrical fires that can be caused by electrical arc and sparks.

They are constantly monitoring the circuit for specific signs and changes in the electrical current that might be a sign of electrical arc happening, and when they register such changes, they trip the breaker immediately. They are invaluable as such electrical arcs can happen and they have been a leading cause for electrical fires.

What causes electrical arcs?

An electric arc is the jump of electricity between two metal contact points. These can be two metal wires that have corroded with time, have damaged insulation cover, or if they have been installed loosely.

In the case of an arc fault, the electricity is using the air as a conductor to flow between the two points.

Other causes for arc faults can be electrical equipment failure, improper installation, and even the accumulated dust and grime on the conductors.

Are arc faults dangerous?

Arc faults can be incredibly dangerous and hazardous. If your arc fault breakers keep tripping there could be several reasons for that and should never be ignored. Have a certified electrician inspect the electrical system if necessary in order to avoid any potential hazards.

Arc faults generate high amounts of heat that can lead to high degree burns and electrical fires.

What Causes the Arc Fault Breakers to Keep Tripping (Nuisance Tripping)?

If your AFCI breakers keep tripping this needs to be inspected as soon as possible as it can be a sign to a potential hazard.

When an AFCI keeps on tripping for no apparent reason, this is called nuisance tripping. Nuisance trips can happen as a result of:

1. Improper wiring

Nuisance tripping is something that a lot of people might not really like about the arc fault breakers, but usually this is happening due to improper installations and specific wiring practices. All connections should be tight and installed correctly.

Improper wiring can even cause the breakers to trip when there is no load in the circuit.

2. Electronic appliances

Some electric home appliances, tools, and devices can cause AFCI breakers to trip.

Primarily any machine equipped with a motor with brushes. When powered, these motors will be generating sparks, and this used to cause AFCIs to trip.

Although that has been fixed and AFCI breakers are a lot smarter today and can differentiate between power tools and a real arc fault, some household items can still lead to nuisance tripping, especially older products.

Such electronic devices are:

  • Treadmills.
  • Vacuums.
  • Power tools.
  • In some cases, even TVs and fluorescent lights can cause AFCI to trip.

A good rule of thumb is to try placing the same electric device on a different electrical circuit and see if the breaker trips again this would confirm that either the device is incompatible with the AFCIs, or that there is a serious problem with the device itself. If it doesn’t trip the breaker, then a certified electrician should inspect the tripping breaker.

If you are not sure what causes the AFCI to trip you can try unplugging everything and start plugging the devices back to the circuit one at a time in order to see when the breaker will trip.

3. Old AFCI breakers

The NEC first introduced AFCIs back in 2002. Since then, there have been a few revisions that lead to AFCIs being required in more and more areas and rooms.

Older units can frequently trip due to the normal wear over the years. Just like any device they can suffer from wearing off, this can easily be fixed by testing them monthly and changing them with newer units if and when needed.

4. Other electrical circuits

The way AFCIs works is by monitoring the circuit for any signs of an arc happening.

However they can detect an arc happening on a completely separate electrical circuit that may be located in very close proximity to the circuit the AFCI is protecting.

An electrical arc happening on such a circuit and the respective changes in the static will be registered by the breaker and it will trip even though its circuit has no signs of an arc happening.

How to Test if an AFCI is Working Properly?

In order to make sure your arc fault breakers are working properly, regular monthly testing should be performed. If they fail the test, they should be immediately replaced by a certified electrician.

The test button’s purpose that is found on the AFCI breaker is to test the proper functioning of its electronics. This ensures that the breaker is working as it should be and that if any signs for electrical arcing are detected, the device will trip successfully.

How is the test performed:

  • Find the AFCI breaker on the main electrical service panel.
  • Make sure you unplug any devices from the outlets to avoid any possible damage to them (especially personal computers and other electronics).
  • Press the Test button, this is going to simulate arcing, and the breaker should trip cutting out any power output to the circuit; as a result, the should be no power.
  • After that, you can flip the breaker back to the ON position, and now there should be electricity running in the circuit.

If the breaker doesn’t trip and cut the power when you press the test button this would mean there is a problem with the breaker and should be inspected and replaced immediately in order to avoid any potential hazards.

Where AFCI Breakers Need to be Installed

AFCI breakers are required by the NEC to be placed on any habitable room that has 120 volts, 15 to 20 amp circuits that have outlets and other devices on them.

  • They should be installed in kitchens, family rooms, dining rooms, living rooms, dens, bedrooms, hallways, laundry areas, and more.
  • They are required in all areas except bathrooms, garages, and any external areas.

AFCI and GFCI Dual Function

Normally an AFCI cannot protect against a ground fault, and respectively, a GFCI cannot detect and protect against an arc fault.

A lot of the locations where the NEC requires a GFCI to be installed also have to have AFCI protection too. Before we had to deal with this very peculiar situation where the only possible option for most people to actually meet the requirements was to install an AFCI breaker and then GFCI outlets down the circuit.

However, with the improvement of technology today, we can actually buy a dual function receptacles that offer both GFCI and AFCI protection for our homes. Quite literally taking the best of both worlds and combining them into one neat package in the form of a receptacle with, you guessed it, two very familiar buttons in the middle.

A dual-function receptacle like this is a great way to save some money and time when it comes to the installation and protection of your home against any electrical faults.

If you are having issues with an arc fault breaker that is continuously tripping you should contact a licensed electrician. Switching out the AFCI breaker out is a relatively straight forward job and can likely correct the problem of nuisance tripping.

This is not a do it yourself job as one working with electricity is dangerous and two special knowledge is required to be sure the correct AFCI breaker is used for your electrical panel box and circuitry.

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Hubert Miles

I've been conducting home inspections for 17 years. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and FHA 203k Consultant. I started HomeInspectionInsider.com to help people better understand the home inspection process and answer questions about homeownership and home maintenance.

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