Smoke Alarms and Outlets

Discussion in 'Electrical Forum discussion & Blog' started by ScottTENN, Dec 2, 2008.

  1. ScottTENN

    ScottTENN New Member

    Messages:
    19
    2 questions.

    #1
    I know I need smoke alarms and CO2 alarms in the basement but I cant fine any thing on how many. See image.

    I figured a CO and smoke alarm (and I know there are different kinds) in the furnace room, far from the ignition source of the furnace and hot water heater.

    Does the theater room need its own smoke alarm? It is about 12x25. The yellow dots are approximate locations of installed can lighting or fluorescent strips.

    Is it also true that you just tie the alarms to well used circuits? Just tap the lighting circuit? That way if the lights are not working then I know the alarm is not working too right. They dont need their own ciruit I guess is what I'm asking.

    [​IMG]
    (not to scale and generalized)


    #2
    Is it acceptable to wire outlets in a "T" shape where the leg of the T is the source and the top of the T are the outlets? I'm guessing it doesn't matter. The source comes in and then is branched out along the wall. Illustrated by the thin red line.

    Thanks
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,323
    Location:
    New England
    All of the smoke detectors I've seen specify a dedicated circuit. They also require them to be interconnected so if one goes off, it trips the others. This interconnection circuitry usually requires the detectors to be from the same manufacturer, but some do offer an extra cost compatibility adapter. The industry standard recommendation is to replace the smoke detectors every 10-years, so it might be time to do them all in the house. Recent changes to the codes require more detectors than previous code releases...you'd need to find out what code your town is currently using. You could always do it per the newest set of code. Don't quote me, but I think it now requires one in each bedroom and at least one on each floor, all interconnected and a/c powered (so people can't steal the batteries and make the non-functional!). My personal preference is to also have battery backup and a momentary alarm suppression button. The time you may need them most is possibly during a lightning storm when the power is out...a fixable deficiency in a/c powered detectors (add a battery backup!). Many allow you to use a lithium battery that could last the entire 10-years without ever having to change it out (depends on how often and long power outages are).

    The bathroom requires a dedicated 20A circuit, and might need more than one depending on what you have planned for it.

    A home theater room could be drawing a lot of power...I think you'd want more than one circuit there as well. Your panel may not have enough spare slots...time to bite the bullet and either add a subpanel, or replace with a larger panel.
  3. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,566
    Location:
    North Carolina
    Smoke alarms are an issue of the building code and are not in the electrical codes. The one thing I am sure of is that all the smoke alarms are required to be hard wired and battery back up type that interconnect. There shall be one inside each bedroom and imediently outside each bedroom and one on each floor level.

    I am assuming that by the word outlet you are referring to receptacles. The receptacles can be fed in any manner you desire as this is a design issue and not a code issue as long as all splices and joints are in an enclosure.
  4. ScottTENN

    ScottTENN New Member

    Messages:
    19
    I had read about the interconnective issue. I will have to see how the rest of the house is wired for this. The house is ~20 years old. At least I would be able to wire the basement one together. This is a two story house with a basement. I have read that in the case of an addition, which this is, the alarms must by interconnected, but not necessarily to the rest of the house. Maybe I can drop a line some where and pickup the remote trigger. Can you even buy an alarm without a battery backup?

    All the outlets/recepticals are 20 amp and lighting 15. The bathroom is on its own 20amp and CFI circuit at the sink. 2 light fixtures and 1 receptical on same circuit.

    The electical room is the 100amp sub panel for the basement, ethernet, cable...

    There are no "bedrooms" though I can see the theater being used as a guest room. That is why I put in a shower in the bathroom, not just a vanity. I figured an alarm in the theater room (since it can be closed off and possible future bedroom), furnace room and in the opposite corner from the theater. (bottom left corner of the image)
  5. jar546

    jar546 In the Trades

    Messages:
    432
    Location:
    USA
    Smoke Alarms

    *One Inside Every Bedroom
    *One Outside the Bedrooms in a common area such as bedroom hallway.
    *One on each floor INCLUDING the basement
    *Hardwired and interconnected with battery backup so that if one goes off, they all go off

    So a ranch house with a basement and 3 bedrooms would have 5 smoke detectors.

    A two story house with a basement and 4 bedrooms will have 7 smoke detectors
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,323
    Location:
    New England
    Note, if you put in CO2 detectors, they'll be going off constantly...too much CO2 could kill you, but CO, carbon monoxide will do it a lot quicker!
  7. seaneys

    seaneys New Member

    Messages:
    192
    Location:
    Chicago Suburbs
    I think he is preparing for global warming :).
  8. seaneys

    seaneys New Member

    Messages:
    192
    Location:
    Chicago Suburbs
    In our village they 'like them to be on a dedicate circuit', but it is not required. They can share a circuit BUT they must not be switched.

    As far as locating the units, my smoke alarms specify one every 30 feet.

    Steve
  9. ScottTENN

    ScottTENN New Member

    Messages:
    19
    Not at all, just some excited fat fingers. CO (carbon monoxide) is what I meant.

    Thanks for the help
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,323
    Location:
    New England
    Most things the inspectors want installed per the manufacturer's instructions, and it is those that often say put the detectors on a dedicated circuit. Local rules prevail, though, so do whatever they want. Functionally, they'll work fine tied into something else, but I'd be wary about putting it on something with a recepticle that could overload the circuit and kill your safety net. Same thing about GFCI, I certainly wouldn't want it on one of those...in fact, when they did trip, it probably would trip a GFCI, since some current has to go out the trigger line, and would no longer be balanced hot to neutral.

    I make typos all of the time! Just wanted to nix perpetuating CO2 verses CO. CO is pretty nasty as it attaches itself to the red blood cells and won't let go - basically, asphixiating you. CO2 is pretty inert, and is a byproduct of us just living.
  11. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,566
    Location:
    North Carolina
    Jim

    The ICC (building code) requires that the smoke alarms be tied to a circuit that has other items on them so the end user won’t be inclined to turn them off and the battery die.

    As far as them being arc fault or ground fault protected each unit has a battery that takes over in the event of a power failure.
    Again should either trip out and the smokes are tied on a circuit with other items the user will be alerted of the problem where as if they were on a circuit to their self the user might not be aware of the issue and the battery die.

    Smoke alarms will be required to be on arc fault, under the 2005 code because they are required to be in the bedroom and the 2008 code simply because they are 120 volt.
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