Adding a Bath Electrical Circuit

Discussion in 'Electrical Forum discussion & Blog' started by diydude, Jul 30, 2012.

  1. diydude

    diydude New Member

    Messages:
    62
    Location:
    Seattle,WA
    Hi,

    I'm new here, but I've fished around for info on occasion. I'm remodeling a small bathroom (about 5' x 10'), which includes adding a recessed light in the shower and radiant heat for the floor (considering 10 sq ft of SunTouch mat: 1-amp draw). My house is 36 years old, and the wiring is a bit funky. There's one 15-amp circuit powering the bathroom that has the following loads:

    Lights fixtures:
    - kitchen (2)
    - chandelier (1)
    - downstairs bathroom (1)
    - deck (1)
    - downstairs bedroom (2)

    Outlets:
    - downstairs bathroom GFCI (1)
    - downstairs bedroom (1)
    - upstairs bathroom GFCI (1) - probably not necessary that it be GFCI, since it feeds off the downstairs GFCI. Anyway.
    - living room (1)

    Other:
    - downstairs bathroom fan
    - kitchen range hood

    Phew!

    Through my investigation of this circuit, I also found that one of the receptacles has a 12/3 wire from a 20-amp circuit running to it that feeds a kitchen receptacle a few feet away. This second receptacle has 14/2 wiring feeding off the 12/3 wire; seems dangerous, but that's another story and something I'll address while I have the wall open by upgrading from 14/2 to 12/2.

    (1) So, I'm trying to think through the best way to deal with the bathroom circuit. My thought was to add a 20-amp circuit for the bathroom that would power the following:

    - GFCI outlet
    - A switch for the shower's recessed light: As a matter of design, are shower recessed lights usually on a separate switch from vanity lights?
    - Radiant floor heater
    - I thought about moving the fan to the new 20-amp circuit - not sure.

    (2) Since the GFCI upstairs is fed off the one downstairs, I was going to swap the 1-gang box downstairs out for a 2-gang to give myself more space to keep the 15-amp wiring as-is in the box. The GFCI upstairs would pigtail directly off the 15-amp circuit in the new 2-gang box and I'd run the 20-amp wiring to the downstairs GFCI in the same 2-gang box.

    [​IMG]

    Does this make sense? Something better?

    Thanks.
    Last edited: Jul 30, 2012
  2. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,532
    Location:
    North Carolina
    In stalll a new 20 amp circuit for nothing but the two bath recptacles.
    Read the installation insturctions for the mat heater as it may call for a circuit for it.

    All the lights can remain on the 15 amp circuit
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,534
    Location:
    Cave Creek, Arizona
    IF your analysis of the bathroom circuit is correct and you really do have all those items connected to it, then it must have been installed by a very incompetent electrician, a handyman, or a DIY homeowner. At the very least you MUST run a new circuit for the items you are installing. A 1 amp draw for the floor mat is about a tenth of what a toaster uses, so I would not expect too much heat from it.
  4. diydude

    diydude New Member

    Messages:
    62
    Location:
    Seattle,WA
    I believe that's how the electrical was originally installed. The baths had/have their original fixtures. I also have a garage circuit that is wired to a living room receptacle; breaker trips when I'm using the miter saw or the table saw and the plasma tv is turned on. I wired a 20-amp circuit in the garage last year.

    Moving the upstairs GFCI to a new 20-amp circuit as jwelectric suggested would probably mean opening a wall, which I'm not sure I want to do. I was going to run a separate 20-amp circuit for the upstairs bathroom later.

    Edit: I could just fish the 12-amp wiring to the GFCI upstairs without tearing into the drywall, but I was worried about the 12" stapling requirement. Is that still a concern?
    Last edited: Jul 31, 2012
  5. Homeownerinburb

    Homeownerinburb New Member

    Messages:
    525
    Location:
    Los Angeles, CA USA
    Regarding the SunTouch mat, absolutely find the manufacturer's installation instructions on that stuff.

    If I did not KNOW for a fact that the mat was correctly installed, I'd certainly not ever use it.

    I would be very reluctant to install that sort of stuff without a GFI to protect people walking over it.
  6. diydude

    diydude New Member

    Messages:
    62
    Location:
    Seattle,WA
    The instructions I saw mentioned a 20-amp circuit with GFCI. The SunStat therm apparently has GFCI. I'll review the instructions included with the actual mat I end up buying to make sure.
    Last edited: Jul 31, 2012
  7. diydude

    diydude New Member

    Messages:
    62
    Location:
    Seattle,WA
    Never mind, I got my answer about the stapling. My understanding is that since the upstairs GFCI is housed in a finished space, I don't need to staple the new wires running to that outlet to the framing.

    My current plan is to run two 20-amp circuits: One for the two GFCI outlets in the bathrooms and a second circuit that runs lights and floor heat in the downstairs bathroom. I want to get the downstairs bathroom off the messy 15-amp branch circuit.

    Thanks to everyone for the responses.
  8. kreemoweet

    kreemoweet New Member

    Messages:
    371
    Location:
    Seattle. WA
    You may well come to regret putting both bath GFCI's on the same circuit. It's been my experience that two blow dryers operating at the
    same time will frequently trip a 20A breaker.
  9. diydude

    diydude New Member

    Messages:
    62
    Location:
    Seattle,WA
    There's only one hair dryer in the house, with no plans for others, so it should be ok.
  10. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,532
    Location:
    North Carolina
    You meant to say one for the receptacles and one for the heat and put the lights on a 15 amp circuit, right?
  11. diydude

    diydude New Member

    Messages:
    62
    Location:
    Seattle,WA
    Ok, please educate me. With the assorted loads on the current 15-amp circuit, I was thinking that I could put the lights and the floor mat on a 20-amp circuit of their own. I didn't read anywhere that the mat needed to be on a dedicated circuit, so I figured this was ok.
  12. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,532
    Location:
    North Carolina
    The lights are okay like they are. It has been working for a while now so no need to mess with them.

    I typed one thing thinking something different above. Although it is hardly legal I would install one 20 amp circuit for one bath receptacle then install one 20 amp circuit for the other baths receptacle. I would then install from the load side of the receptacle to the thermostat for the heat. This way the heat is GFCI protected.

    In most cases it would be okay to figure the heat at 15 watts per square foot. 25 times 15 equals 375 watts. Now 125% will bring this to 468.17 now divide by 120 volts and we have 3.9 amps.

    Once the heat fails then simply disconnect it from the line side of the receptacle.
  13. diydude

    diydude New Member

    Messages:
    62
    Location:
    Seattle,WA
    One thing I forgot to mention is that I'm going to be moving from an overhead vanity to two wall sconces, in addition to the recessed light I'm installing. I believe the draw by the two wall sconces will be equivalent to the current vanity lighting, so I'm thinking it shouldn't be a concern; just need to install two new boxes in place of the vanity box. The radiant floor supposedly only draws 1 amp (I'm only installing 10 sq ft), which is why I was thinking to move the lights to the 20-amp circuit with the floor mat and put both GFCIs on the other 20-amp circuit to make things legal. Also, the thermostat I'm buying for the floor mat has built-in GFCI protection.

    We'll be remodeling the kitchen later, and we have receptacles and switches for the kitchen on the current 15-amp bath circuit, so I wanted to move all the bath items off that 15-amp circuit. A 20-amp circuit does exist for the kitchen in case I need to tap into it for the kitchen additions as an option (most likely recessed lights and maybe a couple other upgrades).
    Last edited: Aug 1, 2012
  14. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,532
    Location:
    North Carolina
    Could you post a link to that thermostat and heat pad?
  15. diydude

    diydude New Member

    Messages:
    62
    Location:
    Seattle,WA
    Sure.

    Here's the owner's manual for the thermostat. I read the instructions a little closer, and they call for a 15-amp breaker max. at the panel to connect the thermostat for the size mat I'm using (10 sq ft). The mat instructions mention a 20-amp circuit - I'm guessing this is for headroom considerations: http://www.warmyourfloor.com/media/thermostats/WR_SunStat_Manual_Programmable_500670-EN.pdf

    SunTouch 4' x 30" mat I plan on installing: http://www.warmwire.com/products/su...-sq-ft/suntouch-120v-mat-30-x-4-12000430.html
    Last edited: Aug 2, 2012
  16. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,532
    Location:
    North Carolina
    When you open that link for the thermostat look at the left of the screen and read line 5

    Edited to add;

    Also look at the bottom of the first page at line 4
  17. diydude

    diydude New Member

    Messages:
    62
    Location:
    Seattle,WA
    Yes, those were the two bullets I noticed when I looked through the manual. I just reread it, and I've got it now. I've decided to stick with my plan to install the two 20-amp circuits:

    - Circuit #1: Two GFCIs
    - Circuit #2: Floor heat, downstairs bathroom fan and lights
    Last edited: Aug 2, 2012
  18. diydude

    diydude New Member

    Messages:
    62
    Location:
    Seattle,WA
    Ok, I have a couple requests for confirmation. I'm running my wiring through the crawlspace. I was reading through Chapter 296-46(B) WAC as is referenced by my city's electrical code (fun reading - NOT!)

    Link to Chapter 296-46(B) WAC: http://apps.leg.wa.gov/wac/default.aspx?cite=296-46B&full=true#296-46B-334

    (1) The "015 Exposed work" section mentions that the NEC protection standards for NM cable in crawlspaces do not apply in Washington; no need to bore holes in floor joists or use running boards when running cable perpendicular to floor joists. I just wanted to confirm and make sure I didn't miss something.

    (2) The other thing I read in section "015 Exposed work" was about a 2 1/2" requirement for cable protection. It appeared to not apply to installations being covered by drywall. The NEC 1 1/4" requirement would apply instead for drywall. Please confirm.

    Thanks!
    Last edited: Aug 4, 2012
  19. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,532
    Location:
    North Carolina
    I think that the link you posted calls for a circuit no larger than 15 amps and for it to be all by itself if possible.
    Being that you are installing this new then it is possible for it to be on a deciated circuit
  20. diydude

    diydude New Member

    Messages:
    62
    Location:
    Seattle,WA
    Yeah, the instructions seem ambiguous. The mat instructions mention the following:

    Maximum Circuit Overload Protection 20 A Breaker
    Maximum Circuit Load 15 Amps

    One other thing I saw, which led me to think that they were providing general NEC-type guidelines for residential circuit wiring, is step 1.2 of the mat instructions. Also, see page 19, which mentions a typical 20A circuit for one mat: http://www.warmwire.com/media/SunTouch-Mat-Do-It-Yourself-D12-Installation-Manual-Current-WYF.pdf

    Also, why would you have a cap on the breaker size if everything is being wired in parallel?
    Last edited: Aug 4, 2012
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