Can the bathroom light be on the same circuit as the receptacle?

Only if that 20 ampere circuit supplies a single bathroom and nothing outside it. The exception to NEC 210.11(C)(3) permits it, and 210.23(B) limits fastened-in-place equipment to 10 amperes on a 20 ampere circuit.

Does a bathroom circuit have to be 20 amps?

Yes. NEC 210.11(C)(3) specifically calls for a 20 ampere branch circuit for bathroom receptacle outlets, which means 12 AWG copper.

How far from the sink does a bathroom receptacle have to be?

NEC 210.52(D) requires a receptacle within 3 feet of the outside edge of each basin, and it cannot face up in the countertop.

What are the code requirements for dedicated circuits in a bathroom?

Section 210.11(C)(3) requires at least one 20 ampere branch circuit to supply bathroom receptacle outlets, and that circuit shall have no other outlets. You have two legal ways to wire it, and the choice determines whether the lights and fan can share it.

Option one: one circuit, all the bathrooms

Run a single 20 ampere circuit that feeds nothing but the receptacles in every bathroom in the dwelling. No lights, no fan, no heater, no outlets in any other room. This is the literal reading of the main rule and it is the version most inspectors expect to see when a house has three bathrooms.

Option two: one circuit, one bathroom, everything in it

The exception to 210.11(C)(3) permits a 20 ampere circuit that supplies a single bathroom to also supply other equipment within that same bathroom, provided the circuit complies with 210.23(B). That is the rule that limits fastened-in-place utilization equipment to 50 percent of the branch circuit rating when the circuit also supplies luminaires or receptacles. On a 20 ampere circuit that ceiling is 10 amperes, or 1,200 volt-amperes.

So one 20 ampere circuit can carry the receptacles, the vanity lights, and the exhaust fan for one bathroom, as long as the fan and any other hard-wired equipment stay at or under 10 amperes combined. A 1,500 watt fan and heater combination is 12.5 amperes and blows past that limit, so it needs its own circuit.

The other bathroom rules that ride along

Section 210.52(D) requires at least one receptacle outlet installed within 900 mm, or 3 feet, of the outside edge of each basin, located on the wall or partition adjacent to the basin, on the countertop, or on the side or face of the basin cabinet not more than 300 mm, or 12 inches, below the countertop. Receptacles are not permitted in a face-up position in the countertop or work surface.

Section 210.8(A)(1) requires GFCI protection for all 125 volt through 250 volt receptacles rated 150 volts or less to ground in a dwelling bathroom. Section 210.8(D) adds GFCI protection for outlets supplying specific appliances, and 210.8(E) covers crawl space lighting outlets. In the 2023 code, 210.8(F) covers outdoor outlets for dwelling unit outlet boxes serving equipment.

Do not forget the definition. Article 100 defines a bathroom as an area including a basin with one or more of a toilet, a urinal, a tub, a shower, a bidet, or similar plumbing fixtures. A powder room with a basin and a toilet is a bathroom. A laundry room with a sink is not.

Field takeaway

Minimum is one 20 ampere circuit with 12 AWG copper for the receptacles. If you want lights and fan on the same circuit, that circuit can serve only one bathroom and the hard-wired load must stay at or under 10 amperes. When budget allows, run two circuits per bathroom anyway, one for receptacles and one for lighting and ventilation, so a tripped hair dryer does not leave the room dark.