We are in the planning stages of an addition to our home. Total square footage is about 150 sq. ft. spread out over 3 floors, or 50 sq. ft. per floor. The addition will include 1.5 bathrooms. I am trying to figure out how many circuits we will need and how best to wire this up. I know as far as bathrooms go I have two options, right? I can either run a dedicated 20 amp circuit to each bath and run everything from that circuit (fan, lights, outlets, etc.) or I can run power all of the outlets from the baths on 1 20 amp circuit and use a separate circuit for the combined lights, fans, etc. Right?

So, I am trying to figure out the best/most efficient option and would appreciate your help. In addition to the bathrooms, each of which will have standard flush mount light, exhaust fan and gfci outlets), the addition will also include electric under floor radiant heat in the full bath, a handful of standard outlets, 2 standard flush mount lights, 3 exterior lights and 2 exterior outlets.

My current plan is the following:

1) 20 Amp Circuit for the full bath (basin outlet, 2 sconces, flush mount light, fan, 2 standard outlets)
2) 20 Amp circuit for half bath (basin outlet, flush mount light, fan, 1 standard outlet)
3) 20 Amp circuit for in floor radiant heat
4) 20 Amp circuit for remainder of use (2 flush mount lights, 3 exterior lights, 2 exterior outlets

Is this sufficient? Overkill? Do you suggest an additional circuit? Can I somehow get away with one less circuit? Is there a better way of organizing it?

Thanks!

I seems you've got the gist of what the code requires.

Assuming you are correct about what the heat requires, those circuits are fine. Yes, there is a way to get away with one less circuit but I would not recommend it. The way to do it would be all bathroom receptacles on a single 20 amp circuit, floor heating on another and the last covering everything else.

I might put the lighting from the bathrooms on the 4th circuit and leave the receptacles by themselves but I'd still have the two bathroom circuits. 2 Hairdryers and fan and lights and curling iron pushes the limits of a 20 amp circuit so I like to keep as much off the circuit as possible.

Also, make sure ALL bathroom receptacles are protected with GFCI. Not just the ones near the basins.

Tev - Thanks! I agree, would prefer to make sure we have sufficient coverage for all possibilities.

Do you think that the 4th circuit will be at risk for being overloaded? Do I need a 5th circuit? Would prefer not to, but don't want to screw myself here.

No, the 4th circuit should be fine even with the bathroom lights on it. Also, don't forget that the outdoor receptacles need GFCI protection.