Wiring Questions For Small Bath Remodel

Discussion in 'Electrical Forum discussion & Blog' started by bosscogg, Oct 9, 2013.

  1. bosscogg

    bosscogg New Member

    Messages:
    11
    Location:
    So Cal
    Hi all, first time poster here. Gotten lots of good advice through the search function, but I've finally hit a wall. And man, what a wall.

    I'm remodeling a small bath and have upgraded the existing fixtures and added a couple more. Previously there was a ceiling light and a medicine cabinet with integrated lights and single outlet, all fed by a single circuit that appears to be 40 amps. I say "appears" because the only way I can kill the power to that bathroom is by flipping a 40a breaker in the main panel. This also kills power to several outlets in other rooms that I know of, and likely others that I don't. There is a sub panel in the house, but none of those breakers affect this particular bathroom. So as far as I can tell, this room is on a 40a circuit. Can this possibly be correct, or is there something I must've missed? My house is almost 80 years old, and it definitely shows in the crazy variety of wires in the attic.

    Clearly I'll need to get this bathroom on its own circuit(s), but how many and what amperage? It now has an LED can in the shower stall, a fan/ light combo in the ceiling, and a vanity light controlled by a single 15a gfci outlet/ switch combo at the sink. As I understand it, bathroom outlets now require dedicated 20a circuits, though there seem to be exceptions (such as when the circuit feeds nothing but the particular room). Does this negate my plan to use the single 15a outlet/ switch? Because also as I understand it, you can attach a 15a outlet to a 20a circuit, but only if there's more than one. That isn't the case here, as my plan only includes a single outlet. Short of adding a duplex outlet or sourcing a 20a outlet/ switch (which doesn't appear to exist in the style my wife wants), is there any safe workaround to this requirement? And further, am I able to wire any/ all of the other fixtures into this circuit as per the exception I noted above? Running an additional circuit is not a big problem, only added work and expense I hope to avoid if at all possible.

    Whew. I'm asking a lot, I know. If anybody's still reading this, thanks for your time and any guidance you might provide.
  2. Reach4

    Reach4 Active Member

    Messages:
    2,219
    Location:
    IL
    I think you want to find the other sub panel.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,990
    Location:
    New England
    Today's code requires a bathroom to have a GFCI circuit for the outlet(s) and be 20A. It can also feed the lights in the room.

    If those things are on a 40A circuit, ALL wiring should be sufficient for 40A, and I doubt that's true! This is a safety (and code) issue. For example, it would be hard to get the wire size required for a 40A circuit to fit onto a 15 or 20A receptacle or switch!

    FWIW, I find the need for more than one duplex receptacle in the bathroom. Charger for my toothbrush, shaver, and a couple of other things keep all of my outlets full pretty much all of the time. I've thought about expanding it to add another!
  4. bosscogg

    bosscogg New Member

    Messages:
    11
    Location:
    So Cal
    I get what you're saying. I mean, this simply doesn't make sense. Thing is, after 9 years here I'm confident there is no other exposed panel...perhaps some ancient who-knows-what buried in a wall somewhere? Circuit mapping by a qualified electrician is definitely in order.

    The wire is ungrounded 12g in a woven sheath, so clearly not rated anywhere near 40a. There's something else in the system I'm just not catching. However, good to hear I can run other fixtures in the room on a new circuit. We have a main bathroom where all the charging, hair drying, etc. takes place, and all I've ever plugged into this back bath in all these years is a shaver. Still, we probably won't be here forever, so surely some expandability will be appreciated by the next guy.

    Thanks for the responses, guys.
  5. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,534
    Location:
    North Carolina
    Is it 12 at both ends? Are there one or two 12s in the 40?
  6. bosscogg

    bosscogg New Member

    Messages:
    11
    Location:
    So Cal
    As obvious as it seems now that you've asked, it didn't even cross my mind to check. I'll do so this afternoon after work and report back.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,607
    Location:
    Cave Creek, Arizona
    NO matter HOW MANY #12 wires are in th e40 amp breaker it is unsafe and "illegal".
  8. Reach4

    Reach4 Active Member

    Messages:
    2,219
    Location:
    IL
    Is the breaker feeding the known sub-panel a tandem (240 volt) breaker? How about the bathroom 40 amp breaker?
  9. dj2

    dj2 Member

    Messages:
    411
    Location:
    California
    The 40 amp breaker was probably installed by someone who didn't have a 20 amp at that moment.
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,990
    Location:
    New England
    The CB is there to protect the wiring. When the CB is larger than the wire's ability to transfer power without heating up too much, it cannot do that. This means, that before the CB would sense a fault from overload, the wire in the wall could have overheated and burned the house down. Except maybe to feed a subpanel, no typical branch circuit with receptacles or lights would use a 40A breaker in a home.
  11. bosscogg

    bosscogg New Member

    Messages:
    11
    Location:
    So Cal
    Thanks for your interest, guys.

    I took a few pics and learned a couple things.


    First, the wires coming from the 40a breaker (lower left in pic) are in fact not #12, they're #6:

    Main Panel.jpg


    They feed through the lower left conduit to a pair of small boxes about 6' away. Was aware of these, but didn't think they were the sub panel(s) Reach4 suggested I find:

    Sub Boxes.jpg


    Had to chip through several layers of paint and mortar to open the right hand box, and found several splices inside. Not pretty, but all wires exiting the box appear to also be #6:

    Box Open.jpg


    It will take some heavier demo to pop the left hand box open, and will do so when I have a bit more time. Wires from the right box enter it, so need to see if that's where they reduce to #12. These boxes are on what was originally the back wall of the house, but a bedroom and bathroom were added years ago. Above these small boxes is a section of wall that has apparently been patched in a different texture pattern. Not too clear in the pic, but quite obvious in person. Perhaps the site of the original, or at least an earlier, main panel?

    Wall Repair.jpg


    Where the wires step down in size is still eluding me.
  12. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,534
    Location:
    North Carolina
    At this point we know that the 40 amp breaker that is controlling the circuit has proper sized conductors. Now awaiting what you find in the other box
  13. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,990
    Location:
    New England
    EVERYTHING that that 40A breaker feeds should have wire capable of safely carrying 40A. Since you have 12g on some of the things controlled by that breaker, unless there's a subpanel somewhere and some more breakers, it is very wrong.
  14. Reach4

    Reach4 Active Member

    Messages:
    2,219
    Location:
    IL
    That is a tandem breaker. That is almost certainly feeding a sub-panel.
  15. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,607
    Location:
    Cave Creek, Arizona
    quote; installed by someone who didn't have a 20 amp at that moment.

    He probably wished they were plug fuses so he could use a penny instead.
  16. bosscogg

    bosscogg New Member

    Messages:
    11
    Location:
    So Cal
    Really appreciate the interest so far, guys. Have to head out of town for a couple days, but will jump on that other box first thing Sunday.
  17. bosscogg

    bosscogg New Member

    Messages:
    11
    Location:
    So Cal
    Finally had a chance to crack open that other box. Found a small fuse panel with one 30a fuse in place. The wires leaving the fuse appear to be #10, but I can't say for sure. Also, if I didn't mention it before, the right hand box has #6 wires exiting through the top that bypass the left fuse box altogether.

    fusebox 1.JPG fusebox 2.JPG

    There doesn't appear to be another junction before the wires head up to the attic. I tried to track the wires once in the attic, but it's an absolute rat's nest of mixed types--knob and tube, metal conduit, older sheathed cable, and Romex. I now doubt I'll be able to find where (or if) the wires step down properly and safely to #12, so have to assume they're at least on that 30a fuse, or worse yet on that 40a breaker.

    We've never had a hint of electrical problems in our 9 years here, but this is obviously a bit worrisome. I'll be contacting a pro soon to get to the bottom of this thing.
  18. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,990
    Location:
    New England
    The only time you'd probably notice a problem is if the wire became overloaded and then started to overheat. Depending on your usage, that may not happen. It's still wrong, and potentially dangerous, and, should be fixed. Having a known fault gets messy with insurance and claims, and, whenever you want to sell the place.
  19. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,534
    Location:
    North Carolina
    Now you are on the right track
  20. bosscogg

    bosscogg New Member

    Messages:
    11
    Location:
    So Cal
    I think you're exactly right (if this turns out to be an actual issue and I simply haven't missed something). We don't have many outlets in this old house, which is what that 40a breaker appears mainly to control...with the known exception of my current bath project. Most of our high-draw items are on dedicated circuits, which could explain why there hasn't been an issue. Yet.

    Yup, when I got a good look in the attic I realized this was a couple notches above my pay grade.

    As for my current bath project, I'd like to move forward in the meantime if possible. I plan to tap into the sub panel in the house, which is properly powered and has plenty of capacity. It is unaffected by the breaker in question, so I feel reasonably comfortable moving forward on that front. Referring to my original post and what I plan to run fixture-wise, am I better off installing a gfci breaker at the panel, or simply a gfci outlet in the bathroom itself? Both? I know there are myriad threads out there on bath wiring, but was hoping for a suggestion specific to this project if at all possible.
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