GFCI/AFCI Install & NEC Requirements
Know where GFCI and AFCI protection is required, choose a device or breaker, wire LINE and LOAD correctly, test the install and diagnose trips.
Table of contents
GFCIs and AFCIs are the two pieces of protection that have changed home wiring most in the last few decades. A GFCI protects people from shock. An AFCI protects the building from fires started by arcing. They use different technology, they are required in different places, and the list has grown in nearly every code edition. This guide covers where each is needed, how to install them and what to do when they trip.
What You Will Be Able to Do
- Explain what a GFCI and an AFCI each detect.
- List the dwelling locations that need each one.
- Choose between a receptacle, a breaker and a dual-function device.
- Wire LINE and LOAD terminals correctly and test the result.
- Find the cause of a repeat trip without removing the protection.
Rules below are from the National Electrical Code (NEC). The current edition is 2026, but many states still enforce 2023 or 2020, and local amendments apply. Your adopted edition is the rule for your job.
What a GFCI Does
A ground-fault circuit interrupter compares the current on the hot and the neutral. On a healthy circuit they are equal. If some current leaks through a person or a damp surface, the two no longer match. A Class A GFCI, the kind used for people, trips at about 4 to 6 milliamps, and it does so in a fraction of a second.
A breaker alone cannot do this. A 15-amp breaker allows 15,000 milliamps. A GFCI opens long before a shock can stop your heart, but you can still feel a painful jolt, and a jolt can still knock you off a ladder.
A GFCI does not need a ground wire to work. That is why the code lets you use one to replace a two-wire receptacle, provided it is marked "No Equipment Ground."
The 2026 NEC also recognizes special-purpose GFCI classes (C, D and E) with higher trip levels. These are for equipment such as certain HVAC units, and they are not substitutes for Class A where the code calls for ordinary protection.
Where GFCI Is Required in a Dwelling
NEC 210.8(A) covers receptacles rated 125 volts through 250 volts on single-phase circuits of 150 volts or less to ground. The list covers:
- Bathrooms
- Garages and accessory buildings
- Outdoors
- Crawl spaces at or below grade
- Basements, finished and unfinished
- Kitchens
- Areas with sinks and provisions for food or beverage prep or cooking
- Within 6 feet of the outside edge of any sink
- Within 6 feet of a bathtub or shower
- Laundry areas
- Boathouses
- Indoor damp and wet locations
Some appliances also need GFCI protection, whether hardwired or plugged in, including dishwashers. In the 2020 and later editions this appears in NEC 422.5.
Outdoor outlets have their own rule in 210.8(F). This one applies to outlets, not only receptacles, so hardwired equipment can be included. The limit rises from 50 amps to 60 amps in the 2026 edition. An exception for listed HVAC equipment expired on September 1, 2026, and the 2026 edition lets certain listed HVAC equipment use a Class C device instead. Some states have amended this rule, so read yours.
How the List Grew
| Edition | Key change for dwellings |
|---|---|
| 2014 | Dishwasher branch circuit, laundry areas |
| 2017 | Within 6 feet of bathtubs and showers, more sink locations |
| 2020 | All basements, 250-volt receptacles, outdoor outlets |
| 2023 | All kitchen receptacles, not only those serving countertops |
| 2026 | Outdoor limit up to 60 amps, new special-purpose classes |
Knowing this list helps on a service call. An older house can be legal as built, without these devices. When you replace a receptacle in a location that now requires GFCI or AFCI protection, the replacement rules in NEC 406.4(D) usually require you to bring that receptacle up to the current requirement.
What an AFCI Does
An arc-fault circuit interrupter watches the current waveform for the patterns made by a dangerous arc, such as a loose connection, a crushed cord or a nail through a cable. A standard breaker may never see these arcs, because the current can be low.
Modern devices are combination type. They detect both series arcs, which occur along one conductor, and parallel arcs, which occur between conductors.
Where AFCI Is Required
NEC 210.12(B) applies to 120-volt, 10-, 15- and 20-amp branch circuits supplying outlets or devices in these dwelling areas:
- Kitchens, dining rooms and family rooms
- Living rooms, parlors, libraries and dens
- Bedrooms and sunrooms
- Recreation rooms
- Closets and hallways
- Laundry areas
- Similar rooms or areas
Bathrooms, garages and unfinished basements are not on that list. A finished basement used as a family room or a recreation room falls under "similar rooms or areas." So in most homes, nearly every 120-volt, 15- and 20-amp circuit in a living space needs AFCI protection. Some states have removed or added locations, so check local amendments.
Extensions. When you modify or extend a branch circuit in one of these areas, it must also get AFCI protection, with limited exceptions. You can use a combination breaker, or a listed outlet branch-circuit AFCI at the first receptacle on the existing circuit. The 2026 edition also permits it at the first switch. A short extension of no more than 6 feet that adds no outlets is excepted.
Choosing the Device
| Device | Protects | Good choice when |
|---|---|---|
| GFCI receptacle | Shock, at that outlet and downstream | Adding protection on an existing circuit |
| GFCI breaker | Shock, on the whole circuit | The location is hard to reach, or you want a clean look |
| AFCI breaker | Arcing, on the whole circuit | Standard new-work bedrooms and living areas |
| Dual-function (DF) breaker | Both | Kitchens and laundries, where both are required |
| Dual-function receptacle | Both, from that outlet downstream | Retrofit on an older panel |
GFCI devices must be readily accessible, so a person can reach them to test and reset without moving appliances or using a ladder. A GFCI receptacle behind a refrigerator does not qualify.
A multiwire branch circuit needs a two-pole GFCI or AFCI breaker. A single-pole device cannot work with a shared neutral.
Wiring a GFCI Receptacle
Warning: Turn off the breaker, lock it out if the work requires it, and prove the circuit dead with the three-step meter check before you handle conductors.
A GFCI receptacle has two pairs of terminals plus ground:
- LINE: the supply from the panel, hot to brass and neutral to silver.
- LOAD: continues to the downstream outlets you want to protect.
Most new GFCIs come with tape over the LOAD terminals. Leave that tape on if you are not protecting anything downstream.
To find the LINE pair when you replace a device:
- Separate the conductors in the box so none touch each other, with the breaker off.
- Turn on the breaker.
- A qualified person tests each cable for voltage. The one that is live is LINE.
- Turn off the breaker, prove it dead again, and label the pair.
Land LINE on LINE. If you connect the supply to the LOAD terminals, a modern GFCI will refuse to reset, which is what it is designed to do. Older models might power the receptacle but fail to trip on a fault, which leaves the outlet with no protection. Those older units are the reason you test each one.
Any downstream receptacle protected this way should have a "GFCI Protected" sticker.
Testing
After every install:
- Press TEST on the GFCI. It should trip and cut power.
- Press RESET. It should hold.
- Use a plug-in GFCI tester on the device and on every LOAD receptacle. It applies a small leak to ground and should trip the device.
- For an AFCI breaker, press its test button. Its light or handle shows a trip.
A plug-in tester needs a ground wire to work, so on a two-wire circuit use the device's own TEST button.
Since 2015, the UL standard has required GFCIs to monitor themselves. A device that fails will usually deny power or show a light. Manufacturers still recommend testing monthly.
Diagnosing Repeat Trips
Never replace a GFCI or AFCI with an ordinary device to stop trips. That removes required protection, it is a code violation, and it leaves the actual fault in place.
Work in order. Unplug all loads, then reset. If it holds, plug loads back in one by one until it trips. If it trips with nothing connected, disconnect the LOAD wires. If it now holds, the fault is downstream.
| Symptom | Likely cause | Fix |
|---|---|---|
| GFCI will not reset with nothing connected | Failed device, or LINE and LOAD reversed | Check wiring, then replace |
| GFCI trips only when it rains | Water in an outdoor box or fixture | Dry, repair and add an in-use cover |
| GFCI trips with one appliance | Leak in that appliance | Repair or replace the appliance |
| GFCI trips on a long run with several loads | Small leaks added together | Split the loads across circuits |
| AFCI trips right after a new install | Neutral shared with another circuit, or neutral touching ground | Trace and separate the neutral |
| AFCI trips with a motor or vacuum | Brush noise from the load, or a loose connection | Try another circuit, then check connections |
| Dual-function breaker shows a code | Ground fault or arc memory | Read the manufacturer's trip indicator guide |
A shared or crossed neutral is the top cause in new work. Each GFCI or AFCI circuit must have its own neutral, landed on the breaker pigtail or terminal as instructed.
Common Mistakes
| Mistake | What it costs |
|---|---|
| Supply landed on LOAD | No power, or no protection on old units |
| Removing the tape and using LOAD with no need | Extra splices and confusion later |
| GFCI hidden behind an appliance | Failed inspection, can't be tested |
| Using a single-pole AFCI on a multiwire circuit | Constant trips |
| Swapping in a standard breaker | Protection removed, and liability for you |
Check Your Understanding
1. A new kitchen receptacle sits behind where the refrigerator will go. Does it need GFCI protection under a 2023 code?
Yes, because kitchen receptacles are covered. Use a GFCI breaker or a readily accessible GFCI upstream, since a device behind the refrigerator would not be reachable.
2. A bedroom circuit is being added. What protection is normally required?
AFCI protection. Bedrooms are not on the GFCI list, unless a receptacle is within 6 feet of a sink.
3. After replacing a GFCI, the RESET button will not latch, and there is no power at the outlet. What do you check first?
Check that the supply is on the LINE terminals. New devices lock out when fed from the LOAD side.
4. A homeowner wants a breaker replaced because their vacuum trips the AFCI. What do you do?
Do not install a standard breaker. Check the circuit for a shared neutral or loose connection. Try the vacuum on another circuit. If it trips only with that appliance, the vacuum may be the problem.
Key Takeaways
- GFCIs protect people by detecting about 5 milliamps of leakage. AFCIs protect buildings by detecting arcs.
- GFCI requirements have grown, and now include all basements and all kitchen receptacles in recent editions.
- AFCI protection covers most living spaces. Know the local edition.
- The supply goes on LINE. LOAD is only for downstream outlets.
- Test every device after you install it.
- A repeat trip is a symptom. Find the cause. Never remove the protection.