The National Electrical Code (NEC) was written to provide a set of rules and regulations to keep the use of electricity in your home safe. The NEC is the basis for most local electrical codes, although the local codes take precedence over the NEC wherever there is a discrepancy between them. The NEC is revised every three years (2017, 2020, etc.) so it is important to use the most recent code when planning a new or remodeled bathroom. While code changes are fairly gradual when it comes to residential wiring, they do sometimes occur, and sometimes the changes are significant.
Important NEC Bathroom Regulations
- General lighting/fan circuit required: Each bathroom should have a circuit for lighting and an exhaust fan. According to the Code, this circuit may be a 15-amp circuit if it serves just lighting, but it should be a 20-amp circuit if it is also serving a vent fan. If the vent fan includes a heat lamp, then a separate 20-amp circuit, in addition to the lighting circuit, should power the vent-fan/ heat lamp combination.
- At least one ceiling-mounted light fixture required: Install at least one ceiling-mounted light fixture controlled by a wall switch to allow ample lighting. This may be in addition to wall sconces or strip lighting in the bathroom. The required ceiling-mounted fixture may be combined with a vent fan unit.
- At least one GFCI-protected outlet required: At a bare minimum, a bathroom needs one GFCI-protected outlet, according to the NEC. But it is much better practice to install two, three, or even more GFCI-protected outlets, especially in a large bathroom. GFCI protection is designed to prevent the shocks that might occur when a ground-fault occurs, and it can be provided by special GFCI outlet receptacles, or by a GFCI circuit breaker that protects the entire circuit. The NEC requires that all outlet receptacles in a bathroom be GFCI protected.
- Outlet circuit must be 20 amps: The outlets in a bathroom should be served by a 20-amp circuit, separate from the lighting circuit, to provide power items such as curling irons, razors, and hairdryers. Heating appliances have heavy power draw, so the Code requires that this bathroom appliance circuit is a 20-amp rather than a 15-amp circuit. It is, of course, allowable to install more than one appliance circuit.
- AFCI Protection: Since 2014, the NEC has required that all outlets serving living spaces in a home, including the bathroom, have a form of protection known as AFCI (arc-fault circuit interrupter). While GFCIs are principally designed to protect against shock, AFCIs serve to protect against arcing (sparking) that can cause fires. AFCI protection is generally provided by special circuit breakers that protect the entire circuit, although there are also special outlet receptacles that provide protection for individual locations.
- Switches must be grounded: Older wall switches often omitted the green grounding screw, but the NEC now requires that wall switches in all locations, including bathrooms, be connected to the system grounding wires.
- Wall switches must be outside tub and shower areas. Unless they are part of the tub or shower manufacturer's assembly, wall switches must be kept outside the confines of a tub or shower area, to discourage users from touching switches while in contact with water.
- A vent fan may be required: The NEC requires that a bathroom must have a vent fan that exhausts to the outdoors if the space does not have a window that can be opened to provide ventilation (providing an opening of at least 1.5 square feet). But some local codes may require a vent fan even if the room does have a window, and it is usually a good idea to include one. The vent fan is often included as part of an overhead light/ heat lamp combination. Many people like to position the vent fan over the toilet area. The NEC does not require that the vent fan have GFCI protection.
The Bottom Line
While older bathrooms were often served by one 15-amp circuit, a new or remodeled bathroom generally requires at least two circuits—a 15-amp or 20-amp general lighting circuit and a 20-amp outlet circuit. A third 20-amp circuit may be required to power the vent fan if it includes a heat lamp.
The NEC offers general guidelines for safe wiring in a bathroom, but remember that local codes always supersede the national code. While many communities base their local codes precisely on the NEC, it is also possible for local requirements to be either more lenient or more stringent, depending on the community.
It is a good idea to check with your local building inspections office to find out the electrical requirements for bathrooms before you plan your new or remodeled bathroom.