2 circuits on a 3 wire

[vdotmatrix]

This is a continuation of the same project, different issue.

BACKGROUND:

• (2) new 20 amp 12/2 circuits (each with own breaker of course), coming from the panel to the switch box in the bathroom.
• New Bathroom exhaust ceiling unit with HEAT, LIGHT, NIGHT LIGHT, and FAN. ( Panasonic FV-11VHL2 )
• (2) 12/3 wire coming from the ceiling unit to the switch box.

• FAN, LIGHT and NIGHT light will share neutral wire from circuit (a) pigtailed in the ceiling unit and in the switch box.
• 4-20A single pole switches in the box will each get their respective BLACK wires from the ceiling unit.

QUESTION:

1. (1) 3-wire cable from ceiling unit back to the box, will control the light (black wire) and night lite(red wire) on circuit (a).
2. the 2nd 3-wire from the ceiling unit will control the FAN (black wire and nuetral from circuit A) and Heat (red wire and neutral from circuit B).

So, if you can follow this narrative, my concern is:

Can I have 2 different circuits within the same 3-wire cable (#2)?

This is OK right?

[HayZee518]

two different circuits on the same three wire cable constitutes a multi-wire circuit and is fed with a two pole breaker common trip. if one side shorts out it will trip the other side also. no seperate circuits here. ask your inspector as you said you pulled a permit for your job

[vdotmatrix]

the heat ,on it its own circuit, has its own switch and it has a separate breaker.
the heat, on its circuit, has its own neutral and black and shares nothing with the other circuit except the YELLOW cable covering.

the fan and lights share their neutral and all have separate switches and a separate breaker on that circuit.

as a last resort i'll call for a survey and have the inspector look at it.

[BBurger]

Put the entire unit on 1 of the 20A circuits, as the manufacturer expects you to do.

Use the other circuit only for receptacles and vanity (if the vanity is no longer on the old circuit).

[vdotmatrix]

I did exactly that!
Circuit (a) was split into 2 branches in a j-box.
One branch supplys the CFGI outlet and vanity light; the vanity light box is now a pass-through for the old circuit!

The other branch continues to the bathroom switch box to supply the ceiling unit with (2) 3-wires switch legs. The FAN,LIGHT and NIGHTLIGHT, use the black(s) and the red from the (2)3-wires on circuit (a).

The HEAT, requires a dedicated 20A circuit, per NEC 2008, uses the red wire from circuit (b); the neutral wires are not shared on this circuit like the are on the other fan circuit. This way, I'd only have (2) switch leg cables of ROMEX coming or going to the ceiling unit instead of (4)!

I went to city hall and showed the electrical code enforcement supervisor this diagram and I am happy to report to the forum that my electrical scheme and assumptions on wiring were correct! Now I am waiting on the special 20A switches and timer! Thanks to everyone for their responses and taking the time!!!

[vdotmatrix]

My Bathroom Project passed ELECTRICAL and MECHANICAL (for the vent) FINAL inspections this morning from the city!!!!!

Hip hip Hooooray!

I want to thank all who consistently help everyone on this forum help us save money and keep our families safe in the dangerous world of DO-IT-YOURSELF!!!