(206) 949-5683, Top Rated Plumber, Seattle
Page 1 of 2 12 LastLast
Results 1 to 15 of 18

Thread: Circuit Planning Basics

  1. #1

    Default Circuit Planning Basics

    About to take on rewiring my house in preparation for a panel upgrade which an electrician will do. Local code allows me to do the wiring for the circuits.

    Been reading a bunch, with a book titled "Wiring a House" as one well referenced book. It's by Rex Cauldwell, a master electrician, published by Taunton. I like a lot of his info, but am unclear on part of the basic circuit planning.

    In talking about the guages of wire he uses, he says he usually reserves 14-3 for one circuit which would have the hard-wired smoke alarms on it and any 3-wire switching items. Ok, that sounds easy. But then he also mentions that all hard-wired smoke alarms must be wired together so that when one goes off, they all go off. Again, no problem, except ...

    He then mentions that it's best to put smoke alarms in the bedrooms, rather than just outside them as code allows. His mapped 2 bedroom circuits, which require AFCI protection, appear to be individual circuits, though.

    Of course, individual houses require individual design of circuit maps. But how can all the smoke alarms be wired together and have the bedrooms be on isolated circuits - not to mention also have the other 3-way switched items on the same circuit?

    My house is small, just 2 BR, 1 bath. If I put the smoke alarms, BR lights for both BR's and other 3-way items on one 14-3 circuit, then I have to make that entire circuit AFCI protected, right? Then, if I do the receptacle circuits for the BR's as two separate circuits, each of these must be AFCI also. Am I thinking of this correctly?

    I guess my confusion is that it seems like on one hand he's showing everything in each BR on it's own AFCI circuit, yet if that includes a smoke detector, then those have to be on the same circuit as the other smoke detectors in the house, which means they can't be on the individual BR circuits.

    Any insight is appreciated.

  2. #2
    Electrician Chris75's Avatar
    Join Date
    Aug 2007
    Location
    Litchfield, CT
    Posts
    608

    Default

    Bedrooms do not have to be on an individual circuit, but they must be AFCI protected, and I usually install my smokes on an individual circuit... FYI, smokes are a building code, so make you check your local requirements...

  3. #3

    Default

    So - to clarify what you're saying - your smokes are then also on an AFCI if they are in the BR?

  4. #4

    Default

    1. One smokie in each BR and one outside the entrance to the bedroom(s). This is USUALLY the hallway.

    2. I don't think the author meant that the 3ways and smmokies should be onthe same circuit but they would use the same wire (14/3)

    3. I THINK they made a changes in 2008 and anything in the BR's must be AFCI. Before it was just recepticals. Not sure.

    4. Forget the notion of a 14/3 circuit. You will have one circuit for both bedrooms including smokies. The 14/3 just runs between the smokies to give them poer (black) and to interconnect them (red). You feed the first smokie with 14/2 and run 14/3 to the others.

    If you WANT to put both bedrooms on seperate circuits fine, but all the smokies have to be on one or the other.

  5. #5

    Default

    Thanks for the input so far. I think I kind of like the notion of doing the lighting and smokes for the BR's all on one circuit, but possibly doing the BR receptacles on separate circuit(s) to allow the possibility of using at least one of the BR's for an office with enough capacity for computer/pro audio equipment. I'd use 12-2 on those circuits.

  6. #6
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,447

    Default

    I know copper is expensive, but consider running heavier gauge wire to the outlets in case you decide you need the extra amperage. An alternative is to run multiple runs to a room. If you don't have central air, also consider a dedicated 20A circuit for a room a/c unit(s).
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  7. #7
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
    Join Date
    Nov 2005
    Location
    Central Florida
    Posts
    2,687

    Default Don't use AFCI or GFCI circuit for fire alarms

    2005 NEC 760.21 says non-power-limited fire alarm circuits shall not be supplied through GFCI or AFCI. Don't know what 2008 says.

    Also, Firex (an alarm manufacturer) recommends you use a "single dedicated AC branch circuit", which would preclude including lighting on the same circuit. Rules and recommendations for new construction are more stringent than for old work.
    Last edited by Mikey; 11-06-2007 at 05:45 AM.

  8. #8

    Default

    Quote Originally Posted by jadnashua View Post
    I know copper is expensive, but consider running heavier gauge wire to the outlets in case you decide you need the extra amperage. An alternative is to run multiple runs to a room.
    Are you saying heavier than 12 guage to the receptacles? That's not common is it? I had considered maybe a dedicated circuit for sensitive electronics, though I'm not sure I'll do that just due to cost. This isn't my dream home by any stretch. My first house and first refurb. A very small house overall.

  9. #9

    Default

    Quote Originally Posted by Mikey View Post
    2005 NEC 760.21 says non-power-limited fire alarm circuits shall not be supplied through GFCI or AFCI. Don't know what 2008 says.

    Also, Firex (an alarm manufacturer) recommends you use a "single dedicated AC branch circuit", which would preclude including lighting on the same circuit.
    I'm guessing "non-power-limited fire alarm" = hard wired smoke alarm? :-)

    So, how can one live up to both parts of the code? My understanding is that everything in a BR must be on an AFCI. Which rule does a person follow when the code seems to be saying 2 conflicting things?

    I probably need to recheck the local codes to make sure.

  10. #10
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
    Join Date
    Nov 2005
    Location
    Central Florida
    Posts
    2,687

    Default

    Quote Originally Posted by cakins View Post
    I'm guessing "non-power-limited fire alarm" = hard wired smoke alarm? :-)

    I probably need to recheck the local codes to make sure.
    Basically, yes. As I understand it, "Non-power-limited" means the kind you and I might install, hard-wired to building power. "Power-limited" means a much fancier version that a pro fire-alarm guy would install, with a transformer or other intervening device between building power and the device. At least, that's what I infer from the Code (760.41). Maybe one of those pros can enlighten me.

    And yes, I think you've figured out how to resolve the conflict -- ask your local guy. The Code clearly says all "outlets" in bedrooms must be AFCI protected, and an "outlet" is any point from which power is taken, so the box on which you mount the alarm would seem to be an outlet. Given the history of AFCIs, if I installed an AFCI on my alarm circuit, I would replace it with a standard breaker as the inspector drove away.

  11. #11
    Electrical Contractor/Instructor jwelectric's Avatar
    Join Date
    Jun 2007
    Location
    North Carolina
    Posts
    2,523

    Default

    Quote Originally Posted by cakins View Post
    So, how can one live up to both parts of the code? My understanding is that everything in a BR must be on an AFCI. Which rule does a person follow when the code seems to be saying 2 conflicting things?
    Quote Originally Posted by NEC
    760 FPN No. 1: Fire alarm systems include fire detection and alarm notification, guard’s tour, sprinkler waterflow, and sprinkler supervisory systems. Circuits controlled and powered by the fire alarm system include circuits for the control of building systems safety functions, elevator capture, elevator shutdown, door release, smoke doors and damper control, fire doors and damper control and fan shutdown, but only where these circuits are powered by and controlled by the fire alarm system. For further information on the installation and monitoring for integrity requirements for fire alarm systems, refer to the NFPA 72®-2002, National Fire Alarm Code®.
    What you are installing in your dwelling unit are “smoke” alarms.

    Each and every “outlet” in bedrooms are required to be Arc-Fault protected.
    Quote Originally Posted by NEC
    210.12(B) Dwelling Unit Bedrooms. All 120-volt, single phase, 15- and 20-ampere branch circuits supplying outlets installed in dwelling unit bedrooms shall be protected by a listed arc-fault circuit interrupter, combination type installed to provide protection of the branch circuit.
    Don’t confuse the word “outlet” and think that it means a receptacle outlet only. In the bedroom you will have receptacle outlets, lighting outlets as well as smoke alarm outlets and they all have to have arc-fault protection.

  12. #12
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,447

    Default

    No, instead of running 14-2 for the outlets, consider maybe using 12-2 in case you decide you need some more current...you could go with a 20A breaker instead of a 15A one. It's easier to do now than redo it later. Course, sometimes having a second 15A circuit is sufficient. A home office can be an energy hog...laser printer, maybe a small frig, computers, shreader, coffee pot, etc.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  13. #13
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
    Join Date
    Nov 2005
    Location
    Central Florida
    Posts
    2,687

    Default

    Quote Originally Posted by jwelectric View Post
    What you are installing in your dwelling unit are “smoke” alarms.
    Yeah, but... my Firex Smoke/CO installation instructions say they're governed by 760. Maybe they've got delusions of grandeur?

  14. #14
    Electrical Contractor/Instructor jwelectric's Avatar
    Join Date
    Jun 2007
    Location
    North Carolina
    Posts
    2,523

    Default

    Quote Originally Posted by Mikey View Post
    Yeah, but... my Firex Smoke/CO installation instructions say they're governed by 760. Maybe they've got delusions of grandeur?

    Could you post these installation instructions

    I couldn't find anything about the "FIRE" alarm in their installations found here nor did they say anything about 760 in this one either.

    EDIT

    Change the word Fire above to Smoke
    Last edited by jwelectric; 11-06-2007 at 10:20 AM.

  15. #15
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
    Join Date
    Nov 2005
    Location
    Central Florida
    Posts
    2,687

    Default

    Here you go... page 4, under "Warning" toward the bottom.

    http://www.firexsafety.com/NR/rdonly...glish12000.pdf

    Quote: "Smoke alarm wiring to be used shall be in accordance with the provisions of Article 210 and 760 of the National Electrical Code..."


    The promo pub (dated 2005) doesn't mention 760, as you pointed out. The installation instructions (which do reference 760) are dated 2006. Whether it's called a "fire alarm" or "smoke alarm" it's clear to me they want it wired i/a/w 760. I just talked with a nice lady in Firex Tech Support, who says that "NFPA is requesting" that they follow 760 in the installation of their smoke/co alarms, which (I assume) is why the instructions were updated and are so worded.

    When all is said and done, I'm not sure how else you would install it, anyway.
    Last edited by Mikey; 11-06-2007 at 07:08 AM. Reason: Added some verbiage

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •