Wiring Diagram for Bathroom

Discussion in 'Electrical Forum discussion & Blog' started by nelsonba, Dec 2, 2007.

  1. nelsonba

    nelsonba Member

    Sep 28, 2005
    I would like to run a new bathroom on one 20 amp circuit. The shortest route for cables would follow this order.

    Panel to GFCI outlet (12/2)
    GFCI outlet to 1st wall sconce (12/2)
    1st wall sconce to 2nd wall sconce (12/2)
    2nd wall sconce to vent fan/light combo (12/2)
    vent fan/light combo to dimmer switch for light and regular switch for fan (12/3)

    Is this possible to do?

    If so, can anyone point me to a wiring diagram or tell me how to do it?

    My other option would be to follow this order, which is easier, just requires more cable.

    Panel to GFCI outlet (12/2)
    GFCI outlet to dimmer switch for light and regular switch for fan (12/2)
    dimmer switch for light and regular switch for fan to vent fan/light combo (12/3)
    vent fan/light combo to 1st wall sconce (12/2)
    1st wall sconce to 2nd wall sconce (12/2)
  2. Alectrician

    Alectrician DIY Senior Member

    Jun 15, 2007
    First, you need a 20 amp circuit (12=2) from the panel JUST for the outlet.

    Your lighting circuits will be seperate. Here (AZ) we can use 15 amp (14 ga wire) for lighting.

    The standard method would be home run from panel (or 120 feed from closest source) to a 3 gang switch box. (sconces/vent light/vent fan)

    From the 3G sw box, run a 2 wire to the first, and then over to the second sconce.

    Again from the sw box run a 3 wire to the vent/light. Black wire light, red wire vent. (you could also use 2, 2 wires...you will have an extra white)

    If you are switching you sconces WITH your light on the vent/light, substitute 3 gang box with 2 gang box. Run the switch legs as described and tie them together in the switch box.

    I am assuming you are using NM or "Romex".

    Use plastic boxes, don't cut your wire too short and TIGHTEN your wire nuts.

    Avoid running power to the light/vent and dropping the switch leg from there as in your origibal plan. You want as little "make up" as possible in the vent fan or lights.
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  4. Bill Arden

    Bill Arden Computer Programmer

    Sep 30, 2006
    computer programmer
    MN, USA
    1. I would not use 14ga on a 20A circuit even if it is allowed.
    It's this kind of thinking that is the source of the whole Arc-fault issue.

    2. I find that making things logical to be a lot easier to understand latter.
    So use the extra wire and large deep boxes. Check the CU(cubic inch) numbers.

    3. You can not (as I understand it) run more than one power source into a box using separate cables. So it's best to use 12-3 or 14-3

    4. Why can't the bathroom have it's own light circuit?
    It would be annoying (and possibly dangerous) if tripping the GFI caused the light to turn off. My house has the bathroom lights wired on the same circuit as the kitchen lights.

    5. I know this is a bit anal, but I like to have the power source enter from the top of the box and have loads exit out of the bottom. I know it makes "make up" a little more complex, but I also tend to use larger boxes.
  5. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Jun 16, 2007
    Licensed Electrical Contractor
    NY State, USA
    Unless a local amendment prohibits it you most certainly CAN have the receptacle and lighting on the same circuit in a bath. That is provided that circuit does not leave the bathroom. This is common in smaller half-baths and such.

    In a full "main" bathroom I would not do it this way. Not for GFI reasons though. There is NO rule that the lighting must be GFI protected, so a tripping GFI is not an issue. It's more a practical issue. Many hair dryers already use most of a circuit, so adding lights and a fan can overload the circuit tripping the breaker, not the GFI.

    I would also run a dedicated 20A circuit for the receptacle. Then I'd run a new (14/2, 15A) circuit for the lighting, unless you can find a lightly used lighting circuit you can tap off of. If there is room in your panel a dedicated lighting circuit is the way to go.
    I promise you, you do not want to have to make up the fan/light with #12 wire. Especially a Panasonic. :mad:
  6. Alectrician

    Alectrician DIY Senior Member

    Jun 15, 2007
    If you were referring somehow to my post, you must have misunderstood something.

    Sure you can.

    Not complex but messy. Running everything in the top allows the wires to be folded in more neatly, giving more room for devices. It also allows for them to be removed/relocated more easily ( I do a LOT or rework).

    You can still be anal if you like. Just run the line in the left and the load(s) out the right :)
  7. nelsonba

    nelsonba Member

    Sep 28, 2005
    How about this...

    OK. So I'll wire just the 20 amp circuit to the GFCI outlet with 12/2.

    For the rest, what should I do?

    1) I'll run a separate 15 amp line for the lighting/vent. Do think I'll be able to chain the sconces on to the vent/light combo? It's a Nutone. I'd like to control all the lights with one switch.

    2) There is a bedroom adjacent to the new bathroom. I had to reconfigure some of the walls and now I need to add some outlets. These need to be ARC-Fault correct? Is 15 amp fine?

    3) I'll have a new closet adjacent to the bedroom as well. Can I just tie into the new bedroom outlet circuit for the light?

    4) I'll also have an unfinished storage space and would like to put in a light.

    5) I'll also be adding an outlet to a landing area just outside the bathroom. Can I tap into the bathroom lighting circuit for this?

    6) When running a wire to a switch and then continuing on to anther light or receptacle can I run the power source into the switch box, wire the switch to the wire running to the light, and then pigtail in an outgoing wire that would continue on as a power source to another switch or outlet? If so, is a standard single gang deep box sufficient if it's 14ga wire?

    7) I'll also have an electric heater on it's own 20 amp circuit.

    Can I do the following?

    Circuit #1: 20 amp to bathroom GFCI outlet

    Circuit #2: 20 amp to bathroom heater

    Circuit #3: ARC-Fault 15 amp to bedroom outlets and new closet light

    Circuit #4: 15 amp to storage space light, bathroom lighting, landing outlet.

    I have two open spaces in my breaker box. I'd have to replace an existing 15 amp breaker with a 15 amp cheater, add a 20 amp cheater, and add the 15 amp ARC-Fault Circuit.

  8. 480sparky

    480sparky In the Trades

    Oct 8, 2007
    Electrical Contractor
    Let's get a few items straightened out first.

    1. It is absolutely permissible to have the lights and receps on the same 20a bath circuit. Required bath circuits are covered in 210.11(C)(3)... but there are strings attached.....read & follow the exception. You can put the lights in line before the GFI to keep the GFI tripping from taking out the lights. BUT, once you have something other than the receps on the bath circuit, that circuit cannot leave the bathroom.

    2. It is not permitted to have 14 NM on a 20 amp circuit. Period. At least not in 99.99% of residential applicatons. Ampacity for NM ("romex") starts in 334.80. Putting 14ga on a 20a breaker has nothing to do with arc fault requirements.

    3. You can have as many circuits as you want in a box, as long as box fill (Article 314) is properly applied, as well as 210.4(B).

    To the OP:

    Sounds like your suggestions in your last post are the way to go. Just keep in mind you can't use AFCI breakers on a multi-wire circuit.
  9. Alectrician

    Alectrician DIY Senior Member

    Jun 15, 2007

    Good idea.

    Yes but tie them together at the sw box.



    Yes, provided you went with the seperate lighting circuit.

    Yes but there isn't a standard size. Go with the deepest box you can find (22ci?)


    The AFCI will need a full space.

    I wouldn't put a heater on a twin breaker.

    I would put all the 15 amp stuff together.

    If you have to relocate wires to make room, make sure none of the wires are red. That's a whole nother issue.
  10. frenchie

    frenchie Jack of all trades

    Dec 30, 2006
    Brooklyn, NY and Fire Island, NY
    In addition to what Alectrician said... check the inside panel of the breaker box, it should tell you how many circuits it's rated for. There's a limit to how many cheaters you can use.
  11. nelsonba

    nelsonba Member

    Sep 28, 2005
    Couple more questions

    Why not put a heater on a twin breaker? The heater draws 1500 watts.

    The boxes I got for the sconces are metal. Do I need to pigtail a ground wire to them?
    Are you talking about a double breaker? I realize I'll need a full pole just for the AFCI breaker.

  12. Alectrician

    Alectrician DIY Senior Member

    Jun 15, 2007
    I don't feel that the twin breakers handle bigger continuous loads well.

    Plastic boxes are non conductive=safer. You must bond the metal box. Use one of the NM grounds instead of adding a ground pigtail.

    Stay away from red wires in panel....multi wire branch circuits...two hots, one neutral. Hots must be on seperate phases (legs)
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