I'm having my main bath renovated and will have the old (BX-type) wiring removed. Do I need a 20 amp circuit for the GFI? Do I need more than one circuit, e.g. a 15 amp for the lights and fan, or can it all run off the GFI?

Also, I think I remember something about having the lights on more than one GFI so they don't all go out at once. Is that right? The contractor will do what I want, but I wanted to check on your recommendations.

Thanks

It is ideal to have 2 circuits. One for the GFI outlet and another for the lights and fan.

U can have other outlets on GFI if u want. The same is true for the lights.

Chuck

You can have all of it on one circuit by bringing the home run into the GFCI box first,
Continue the circuit back out (to feed the light/fan switch box) by wirenutting the in and out wires (in the trade these are called line and load) with pigtails to feed the line side of the GFCI. This makes the light/fan switches not GFCI protected (which is not necessary) and they won't go off when/if the GFCI trips.

If you landed the hot and neutral wires (going out/load side) on the Load side of the GFCI switch, (always plainly marked) then the light/fan would go out when/if the GFCI trips.
If you have two circuits sharing a neutral as the home run(14-3), bring it in to the GFCI box and land either the red or the black on the GFCI and pigtail out the neutral(white) and the ground wires to take the remaining circuit out as a (14-2) wirenutting that to the remaining hot wire and the shared neutral and ground.

If you want 20 amp circuit(s) use 12-3 and 12-2 wire

This circuit could also be arranged in a different manner, what I described has the fewest wires at the light/fan switch box.