Thread: new home bathroom branch circuit

Was not clear to me in reading NEC, but is a seperate circuit required for lighting and one for recepticals in a new construction home or is one 20 amp adequate. Also does each bathroom need its own?

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Nevermind, got it.

The NEC is quite clear on this:

A single 20A branch circuit (GFCI protected) is required to service the receptacles in a bathroom. The NEC also allows for that same circuit to be extended to another bathroom's receptacles. (Why, I'm not real sure. Just the possibility of having two women drying hair at the same time using the same circuit and having it trip the breaker is frightening to me. )

Also, the NEC allows for a single 20 amp branch circuit in a bathroom to service other loads in the bathroom, providing you do not exceed the 50% rule.

It is never a good thought to service lighting on the same circuit that uses GFCI protection from a breaker. If the breaker trips, out go your lights and there you sit in the dark.

I'd have to go get my code book to see it is prohibited or not, but I don't think it is. I know it is not recommended to service lighting from a GFCI breaker.

Mike, I see you got it but for others interested EC&M just had an article that covers this subject very well.

Branch Circuit Requirements and the NEC - Part 1#

Originally Posted by Donald Farrell

The NEC is quite clear on this:

A single 20A branch circuit (GFCI protected) is required to service the receptacles in a bathroom. The NEC also allows for that same circuit to be extended to another bathroom's receptacles. (Why, I'm not real sure. Just the possibility of having two women drying hair at the same time using the same circuit and having it trip the breaker is frightening to me. )

Also, the NEC allows for a single 20 amp branch circuit in a bathroom to service other loads in the bathroom, providing you do not exceed the 50% rule.

It is never a good thought to service lighting on the same circuit that uses GFCI protection from a breaker. If the breaker trips, out go your lights and there you sit in the dark.

I'd have to go get my code book to see it is prohibited or not, but I don't think it is. I know it is not recommended to service lighting from a GFCI breaker.

Only the receptacles need GFCI protection, the NEC does not care if the GFCI is a receptacle or a circuit breaker for it. There is no requirement that lighting be GFCI protected unless the manufacturer requires it in certain locations(it may be required in a shower). The NEC allows the required 20A circuit to serve receptacles in other bathrooms but serve no other loads, or it may supply the receptacles & lighting in a single bathroom.

Chris, Excellent article, thanks.

Originally Posted by Donald Farrell

....Just the possibility of having two women drying hair at the same time using the same circuit and having it trip the breaker is frightening to me. ) ....

Bathrooms are often big enough for two to use at the same time (e.g. those with two basins) in which case there could easily be two hairdryers plugged into one bathroom outlet at the same time (the outlets are duplex), so limiting the circuit to serve one bathroom isn't going to eliminate the possibility of breaker tripping due to two hairdryers. Any multiple-outlet or single-duplex-outlet 15A or 20A circuit can be overloaded by plugging in two 10 or 12 Amp devices. In effect this is how we all learn not to plug in that extra 1200 Watt fan heater when the electric kettle is on. The code requirements, e.g. for kitchen counters, reduce the incidence of such nuisance trips but cannot eliminate them unless it required every outlet to be a simplex outlet with a home run to the breaker panel, which is not going to happen. What I would find it frightening is if the breaker failed to trip, not if it trips.