AFCI vs GFCI: Differences & Why Both are Critical to Safety

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When it comes to electrical safety, both AFCI (Arc Fault Circuit Interrupter) and GFCI (Ground Fault Circuit Interrupter) electrical safety devices are critical. But what’s the difference between them? And why are they both so important? Let’s take a closer look.

Electricity in modern houses isn’t just a necessity; it’s also potentially dangerous. Your home is full of high-powered appliances and small electrical devices that have one thing in common. They all need the right amount of electricity running for them to operate. They also require the right protection to ensure that a problem doesn’t occur. 

GFCI and AFCI outlets and breakers are safety measures your electrician should install in your home. While they both play a major role in keeping your home safe, they guard against different dangers. GFCI devices protect you from ground faults, while AFCI devices protect against arc faults. Together, these devices keep your home safe from electrical problems. 

If you’re wondering about the difference between GFCI and AFCI circuit breakers and whether or not you need both of them, you’ve come to the right place. Both devices are essential to your home but in slightly different ways. We’ll explore those ways and where each of these devices should get installed. 

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What is a Ground Fault?

Before you can understand how important protection from ground faults is, you should understand what they are and why they’re dangerous. When your home’s electrical system operates smoothly, electricity enters a device through a hot wire, goes through the device, and exits through a neutral wire. This process repeats continuously until the flow of electricity is stopped, such as by turning off the lights or flipping a breaker to OFF. 

However, when the flow of current from hot to neutral escapes from the circuit and travels to a nearby object, the result is a ground fault. If that nearby object happens to be you, you’ll receive an electric shock, which can turn deadly if the voltage is high enough. 

What Causes Ground Faults

Ground faults often happen because of improper wiring, faulty wiring, or moisture within the outlet. Water damage is the main source of ground fault issues, but it’s not the only reason. They could also happen if your electrical wiring gets disconnected or frayed and comes into contact with the outlet box or a nearby object. 

Ground faults can also stem from old wires that have lost much of their coating or protection. The exposed wiring will come in contact with something inside the wall or attic where it’s located and could potentially start a fire if the object is flammable. 

What is Ground Fault Circuit Interrupter (GFCI) Protection?

A ground fault circuit interrupter, a GFCI device, offers protection against a ground fault’s unlikely but possible occurrence. For example, let’s say that your microwave gets plugged into a kitchen outlet without GFCI-protection. A ground fault occurs within the outlet, resulting in electricity traveling through the cord plugged into the outlet straight into the microwave. 

As a result, the metal shell of the microwave is now energized and essentially becomes a live wire. If you happen to touch the microwave, you will get shocked. Because microwaves typically operate on a high amount of electricity, the amount of voltage in the shock could be enough to kill you. 

If you plugged your microwave into a GFCI-protected outlet, this couldn’t happen. The outlet would detect an anomaly in electricity and automatically kill the flow of electricity. 

What Does a GFCI Device do? 

A GFCI device aims to detect anomalies in the flow of electricity and terminate the flow if it senses any danger. These devices mainly prevent electrical shock to you or a family member, but they can also protect against electric fires or burns. Stray electricity is extremely dangerous and is the cause of scenarios like the one listed above. Here’s how the process works. 

  1. Electricity flows into the hot side of the GFCI device. 
  2. Power then flows through the outlet to the neutral wire hooked into the device. 
  3. If the voltage or amperage coming into the device doesn’t match the electricity on the neutral side, there’s an electricity surplus or some has escaped. 
  4. The GFCI device detects this anomaly and kills power to the outlet before anything bad can happen. 
  5. This process happens in milliseconds and protects you from electrical shock. 

GFCI outlets are the most common GFCI device used in residential and commercial homes. GFCI outlets protect the outlet in question, but they also protect all outlets downstream from it as long as they’re on the same circuit. However, a GFCI outlet can’t protect anything between itself and the electrical panel where electricity originates. 

For that reason, some people like to install GFCI circuit breakers, which then protect every device that’s wired into its circuit. However, this is often overkill unless you have a dedicated circuit for the kitchen or bathroom, and you know every outlet will need GFCI protection. 

Where are GFCI Devices Needed? 

Because the main cause of ground faults is when moisture or water gets into the outlet, you need GFCI devices in areas prone to moisture. Here’s a list. 

  • Bathrooms 
  • Kitchens 
  • Unfinished basements 
  • Outdoor outlets 
  • Barns 
  • Shops 
  • Pool houses 
  • Laundry rooms 

Essentially, any area with electricity and even the remotest possibility of getting wet should have GFCI protection. These handy devices could mean the difference between life and death for you and your loved ones if there should happen to be a ground fault. 

What is an Arc Fault? 

An arc fault is when the metal portion of a live electrical wire comes in contact with another metal source. The touching of electricity to metal will cause sparking and could potentially start a fire if the spark hits a nearby flammable object. Arc faults happen more often than you would think, but thanks to AFCI protection, most of these faults don’t cause any damage. 

Arc Faults vs. Ground Faults and Short Circuits

Many people who aren’t familiar with electrical terms and dangers throw arc faults, ground faults, and short circuits into the same category. While they’re all potentially dangerous electrical problems, their causes and results are very different. 

As we just discussed, arc faults happen when a live wire comes into contact with a piece of metal and forms a spark. Ground faults are when the electrical current travels outside its intended path and electrifies a nearby metal object or person. Short circuits are similar to ground faults in that they result from a sudden excess of electricity or when electricity escapes from its intended pathway. 

However, the usual result of a short circuit is that the sudden burst of electricity causes the circuit breaker to trip, which kills the flow of electricity and stops the danger. Arc faults are so dangerous because an arc fault occurrence won’t trip the circuit breaker unless they lead to a ground fault or short circuit. While tripping the breaker is a possible outcome, there’s no guarantee that an arc fault won’t create heat or a spark and start a fire instead. 

What Causes Arc Faults? 

According to the Department of Economic and Community Development Building Division of San Francisco, California, “Arcing faults often occur in damaged or deteriorated wires and cords. Some causes of damaged and deteriorated wiring include puncturing wire insulation from picture hanging or cable staples, poorly installed outlets or switches, cords caught in doors or under furniture, furniture pushed against plugs in an outlet, natural aging, and cord exposure to heat vents and sunlight.” 

Arc faults can also happen when a bare electrical wire comes into contact with an object and creates extreme heat rather than a spark. Once the electrical wires get hot enough, they could start a fire unless they trip the circuit breaker first. However, because high heat usually isn’t enough to trip a breaker, AFCI-protection is necessary. 

Because of how dangerous arc faults are, it’s crucial that your licensed electrician properly install your electrical branch-circuit wiring. The use of up-to-code wire nuts and electrical materials is a necessity when it comes to electrical work. Here’s a complete list of the known causes of arc faults. 

  • Damaged wires or wires that overheat because of an overloaded circuit and melt their insulation 
  • Electrical wires that attach incorrectly to electrical devices such as lights, outlets, or appliances 
  • Pierced or damaged wire insulation because of nails, staples, or metallic fasteners of any sort
  • Outlets, lights, appliances, or electrical branch circuits that get damaged in any way 
  • Damaged extension cords that attach to a live electric current and device 
  • Cords or wires in your attic or outside your home exposed to the sun or other sources of intense heat for prolonged periods 
  • Any sort of damage to electrical wires or their insulation

Combination arc fault circuit interrupters (CAFCI) protect against all electrical faults and meet National Electrical Code requirements for circuits that need both AFCI and GFCI protection.

What is Arc Fault Circuit Interruptor (AFCI) Protection? 

AFCI breakers are much newer than GFCI breakers regarding when they became a requirement. AFCI devices were invented around 1999 and quickly became a mainstay in millions of homes worldwide. Today, AFCI-protection is often a requirement according to local building codes and the National Electric Code (NEC). 

Originally, AFCI protection was only required in bedrooms since they presented the highest risk of fires starting unnoticed. However, AFCI protection became mandatory in many rooms throughout your home before long, even if you didn’t know it. 

The main purpose of having AFCI devices is to protect against electrical fires or an overheating wire. Fires can stem from any scenarios and reasons listed above and are a hazard with life-threatening consequences. A superheated electrical wire can result from sun exposure, worn-out wires or electrical cords, or an overloaded electrical circuit. 

What Does an AFCI Device do? 

Here’s how an AFCI device protects against dangerous electrical arcs and sparks. 

  1. You install an AFCI outlet or circuit breaker along the desired circuit. 
  2. If the device detects any signatures of arcing or electrical anomalies, it terminates the current flow of electricity. 
  3. The process is similar to how GFCI devices detect danger and kill power. 

Unfortunately, early AFCI devices tended to be overzealous and caused a ton of nuisance trips where the device mistook normal electricity for arcing. However, technology has come a long way since the early 2000s, and much of that problem is gone. The detection of arcing signatures and overheated wires is instrumental in preventing fires. 

Where are AFCI Devices Needed? 

Because AFCI devices are necessary for an entire circuit rather than an individual outlet, they almost always get installed at the electrical box as a circuit breaker. GFCI outlets are great for one, two, or even a short series of electrical outlets, but the entire circuit require AFCI protection. While you can install them on any circuit in your home, here are some of the standard locations for AFCI devices. 

  • Bedrooms 
  • Living rooms 
  • Library rooms 
  • Dining rooms
  • Family rooms
  • Laundry areas 
  • Entry areas 
  • Hallways 
  • Recreation rooms 
  • Gyms 
  • Kitchens 
  • Sunrooms 

In other words, AFCI protection is a good idea for every room in your home, especially the ones listed above. 

Related Questions 

Which is better, GFCI or AFCI protection? 

Rather than choosing between GFCI or AFCI protection, you should have both forms of protection implemented in your home. The devices protect against different things, which means that they’re equally important. 

Do I need both GFCI and AFCI protection? 

AFCI protection prevents fires from overheated wires or when a wire touches metal. GFCI protection guards against fatal electrical shock due to a ground fault. Their purposes are different, so it’s a good idea to have both of them in your home. 

When should I not use AFCI? 

AFCI protection is required almost everywhere in your home. However, the exception to this rule is that they don’t have to have AFCI protection for extension cords or wires that are less than six feet long. 

Can you put a GFCI outlet on an AFCI breaker?

It’s ok to put a GFCI outlet on a branch circuit with an AFCI breaker. The NEC now requires circuits like kitchens and laundry rooms to have both arc-fault and ground-fault circuit interrupter protection. A combination air-fault circuit interrupter (CAFCI) will also meet the NEC requirement where you need both AFCI and GFCI protection.

What is a GFCI breaker used for?

You can use a GFCI circuit-breaker anywhere GFCI protection is required. However, the most common use is for specific locations where you need a GFCI device but the area is not readily accessible.

For example, electrical outlets in a crawl space require ground-fault protection. Adding a GFCI breaker in your breaker box allows you to access the GFCI without having to enter the crawl space.

Final Thoughts 

It’s tough to estimate how many lives and homes have been saved in the past forty or so years because of GFCI and AFCI protection. Both forms of protection are instrumental in ensuring that you and your home stay safe. While they’re each important on their own, using both types of devices simultaneously offers a stronger guarantee that you’ll be safe in your home from electrical shocks and fires. 

Hire an Electrician

Get FREE estimates from licensed electricians in your area today. Whether you need to replace an outlet, hang a ceiling fan, a new electrical panel, or repair wiring, We Can Help!

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Hubert Miles | Licensed Home Inspector, CMI, CPI

Hubert Miles is a licensed home inspector (RBI# 2556) with more than two decades of experience in inspection and construction. Since 2008, he has been serving South Carolina through his company, Patriot Home Inspections LLC. As a Certified Master Inspector, Hubert is dedicated to providing his expertise in home inspections, repairs, maintenance, and DIY projects.