What is GFCI protection and where is it required in an ADU?

GFCI — ground-fault circuit interrupter — protection is a fast-acting device that monitors the current going out on the hot conductor versus the current returning on the neutral, and cuts power within milliseconds if it detects an imbalance, such as current leaking through a person to ground. It's a shock-prevention requirement, and California requires it throughout an ADU's wet and outdoor locations. Locations must be shown on the electrical plans.

Where GFCI protection is required

In a California ADU, GFCI protection is generally required at receptacles and circuits serving:

• Kitchen countertop receptacles, including the two small-appliance circuits.
• Bathrooms — all receptacles.
• Garages and accessory buildings.
• Outdoor receptacles.
• Laundry areas and any receptacle near the laundry sink.
• Anything within 6 feet of a sink, including a wet-bar or utility sink.
• Crawl spaces, unfinished basements, and similar damp locations.

Recent code cycles have also expanded GFCI to certain dedicated appliance circuits in some jurisdictions, so the exact list depends on your adopted code edition.

How it's provided

GFCI protection can be delivered two ways, and the plans note which applies to each circuit:

• GFCI receptacle — a device receptacle with the test/reset buttons, which can also protect downstream outlets wired to its load terminals.
• GFCI circuit breaker — protects the entire branch circuit from the panel, often used where a combination AFCI/GFCI breaker is the cleanest solution.

GFCI vs. AFCI — they're not the same

GFCI guards against shock by detecting current leaking to ground; AFCI guards against fire by detecting dangerous arcing in the wiring. Many habitable areas require both, which is why dual-function AFCI/GFCI breakers are common on ADU panels.

On our electrical plans, every GFCI-protected outlet is identified on the power plan and the panel schedule, and the general notes cite the code edition. Missing GFCI coverage in kitchens, baths, garages, and outdoor locations is a leading inspector catch — especially in garage conversions and legalization cases — so we map it out before submittal. Requirements vary by jurisdiction and code cycle; confirm with your local building department.