Long time reader, first time poster… so I thought I had my bathroom wiring layout pretty well nailed but the guy in the electrical department at the local big box store made me rethink my entire plan.
My original plan:
20A feed to bathroom from breaker box. That goes to the same wall box as GFCI outlet. The feed line from breaker is pigtailed to both the GFCI outlet above the sink (plus one normal outlet fed off this GFCIs LOAD) and the other feed goes to vanity light/fan/ceiling light 3-gang switch box. Inside 3 gang I would have a dead-front GFCI, a combo vanity light/fan switch, and a dimmer switch for the lights. The ceiling light/fan need GFCI because the manufacturer says so above the shower (broan 744).
Now the issue: The guy at (big box store) said you cannot have two GFCI on the same circuit at all because it will make neither of them trip and to just run the light/fan/vanity light all off the one GFCI. I feel like this is a big no-no because if anyone trips the GFCI while they are in the shower (like a curling iron left on sliding into the sink) the lights will be off and they will have to get out of a slippery wet shower in the dark or even if they were just using a curling iron while in front of the sink they wouldn't be able to see to set it down. I think my original plan would eliminate this because if the GFCI on the outlet plug blows then the lights (on a different GFCI) would not blow. He also said I cannot use canned IC recessed lighting in a bathroom at all without a glass shower trim ring. I was under the impression that you could use normal baffled recessed lighting in a bathroom as long as it was not above the shower.
Is my proposed setup unsafe? I don't care if I am wasting money on an extra dead-front GFCI if it means the lights stay on when my girlfriends ancient favorite blow dryer starts. Also, I know I could just run another 15A lighting circuit to the breaker box but I am all out neutral lugs (generator transfer switch install, it's a mess I didn't do it). Thanks for your time 🙂
Best Answer
The bloke at the big-box store is out of his mind. Having multiple GFCIs fed from the same feed is not a problem whatsoever -- it's something that's done all the time (just imagine a panel loaded with GFCI breakers). Furthermore, the requirements for fixtures in 410.10(D) only hold for a zone that extends 3' beyond the edge of the tub or shower stall and 8' high. Ordinary fixtures can be used outside this boundary.
In your case, given that your choice of fan/light combination apparently must be GFCI protected in order for it to be used in a damp environment, your solution is a reasonable compromise given that you are using a dimmer here. However, it is possible to make it so that the shower light is GFCI protected while the cans are not, while dimming them both synchronously, but that requires a fair bit of extra hardware.
In particular, you'd need to use a 3-wire fluorescent dimmer such as a Lutron Maestro MAF-6AM or Skylark SF-103, as well as two Lutron PHPM-WBX-120-WH units mounted in their own two gang or 4" square boxes to go with the 3 gang box you're already called for. (Other manufacturers make similar products, but both the Leviton and Eaton/Cooper versions are FCC Class A devices i.e. not intended for residential use.)
If you're curious as to how such a crazy setup is wired up, see the wiring diagram below. If you're not comfortable following the diagram below, ask your nearest electrician to follow it for you.