I am remodeling my bathroom and replacing the old HVL with a new Broan 100HL. Rather than use the Broan switch which has 3 switches in 1 gang, I am using a standard switch and a combo switch. I'm not sure my diagram is correct. Would a hot wire need to jump over to the combo switch? It seems to me that the combo switch won't have power in from the panel, therefore it would not have a circuit to break. I'm thoroughly confused and would appreciate any help! Thanks in advance!! wiringdiagram

2 Answers 2


Since the three switches & devices are all in one circuit, they need to share hot (panel to the switches) and neutral (from the devices back to the panel).


Take the hot wire off the vent switch. Typically there is a jumper/bridge connecting the two hots (i.e., to make a common hot connection) on the double switch. Assuming that is the case, connect two short pieces of black wire with a wire nut to the hot wire that you removed from the vent switch. Connect one of those pieces to the vent switch and the other to the double switch (heat or light screw, doesn't matter which one).

If there is no jumper/bridge between the two hots on the double switch, then connect three short pieces of black wire with a wire nut to the hot wire that you removed from the vent switch. Connect on to each of the 3 switches (vent, heat & light screws of double switch).


Based on your diagram, you appear to be using either separate wires in conduit or a /4 cable - black/white/red/blue, and joining the two separate neutral connections of the HVL together to the white (neutral) wire going back to the panel. If so, that's fine.

However, if you actually have two separate cables - one black/white from vent switch and one black/white/red from the double switch then you have a bit of a problem. Each neutral in a cable has to match the loads in the cable. Based on the diagram, the light & vent (which each typically use < 100W) share a neutral and the heat (typically ~ 1500W) has its own neutral. You can't mix & match neutrals. Either they all get combined and the neutral wire runs next to all the switched hot wires in conduit or in a single cable, or then must be kept matched together. To keep them matched together in cables, the white (neutral) for the light & vent must be together with the switched hots for those devices and only combined together with the heat's neutral in the switchbox - not combined at the device.

  • Thanks for the help! I actual have a /3 piece of Romex (BK/R/W) and also a single strand of Blue running from the switch to the HVL. If I understand correctly, all I need to do is add a jumper/pigtail from the Vent switch to one of the black screws on the combo switch? The combo switch is bridged. I sincerely appreciate your help!!
    – Mark
    May 5, 2019 at 20:23
  • You have two separate issues. Hot can be solved by (conceptually) a jumper from Vent to one of the black screws on the combo switch. But normally you can't put two wires under one screw, so you make a pigtail (as I described) to connect the extra wires. But the much bigger problem is the neutral - /3 + 1 is not equal to /4. You need either /4 or /3 + /2 wired correctly. "Correctly" in this case meaning "neutral (white) matched to switched hots based on device configuration and not switch configuration". May 5, 2019 at 20:32
  • Thank you!! That's exactly what I needed to hear!!
    – Mark
    May 6, 2019 at 5:12

You're likely violating local building codes and the NEC with this. If your bathroom is 100% supplied by a single branch circuit then your upgrades must split this into two separate circuits unless a very specific set of circumstances exist here... with this device you are prohibited from installing it if that condition exists..

Have you pulled a permit?

Have you read the installation guidelines from the manufacturer?

Whenever the manufacturer specifies that the device be contained on it's own branch circuit then you can't install this fixture unless it's supplied by it's own branch circuit!

This fixture CLEARLY states it must be installed on a separate 20A branch circuit.


If this is the typical bathroom remodeling job I'd advise you to immediately STOP and assess the existing branch circuits and before you proceed, you must fully understand the codes and rules designed to protect you and your family (and subsequent homeowners) from installing this dangerously inappropriately.

  • 1 - No indication that this is the only branch circuit in the bathroom or that it is supplying receptacles - i.e., no reason to jump to the "violating NEC" statement; 2 - permit - when/where that is required is location dependent; 3 - the device as a whole - heat, vent & light together needs a 20A circuit. Again, no indication that OP is doing anything other than exactly that; 4 - no indication this is a remodel - sounds just like a replacement of the fan/light - nothing more, nothing less. May 6, 2019 at 4:09
  • 1
    My bathroom is actually supplied by 3 circuits. I have not pulled a permit, because our rural area doesn't use permitting. If they did, none would be required for this replacement. I have in-fact read the guidelines. This HVL is supplied by a separate 20A circuit. None of this addressed my question, but your multiple cautions are duly noted.
    – Mark
    May 6, 2019 at 5:00
  • This is illogical and I can't conceptualize how someone would run three different circuits into a bathroom, especially one that's being renovated right now. May 6, 2019 at 5:04
  • 1
    It was wired that way when I bought the house. With recessed lighting, wall lighting, 7 receptacles, floor heat and a HVL, I guess the electrician that did the original wiring felt differently.
    – Mark
    May 6, 2019 at 5:09
  • 1
    I'm not sure where I said a dedicated 20A circuit isn't available. IT IS presently on a dedicated 20A circuit. I am only replacing an existing HVL with 3 function single gang switch with a new HVL with a standard single switch and a combo switch. I am not re-wiring the neighborhood.
    – Mark
    May 6, 2019 at 5:27

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