Smoke Alarms & CO2 detectors

Discussion in 'Electrical Forum discussion & Blog' started by Master Brian, Oct 13, 2009.

  1. Master Brian

    Master Brian DIY Senior Member

    Messages:
    368
    Location:
    Kansas
    I have a 1915 1-1/2 story bungalow craftsman, which I'm slowly trying to restore.

    In any case, I've started adding some hard wired smoke alarms and CO2 detectors thoughout the house as I tackle an area. So far, I have a combination smoke/CO2 alarm in the basement utility room, a smoke only in the living space in the basement. On the main floor I have a smoke/CO2 detector in the hallway that feeds three bedrooms and a bath and I have a smoke only at the top of the stairway for the 2nd floor, which is open at bottom, but door at top. These are all wired!

    I plan on installing a wired smoke only in the basement laundry, and either a smoke (possibly a combo) in the study at the top of the stairs and a combo unit in the attic space/future storage closet and possible furnace room on the 2nd floor.

    I then have battery only units in pretty much every other room. Should I try to switch those out to hard wired or is it not worth the effort/cost. I guess the question is should the bedrooms be hard wired or not?

    The other question is are the CO2 alarms really worth the extra cost? I realize the danger and my mom lost her mother to CO2 poisoning during a house fire, when my mother was younger. I've just had several people tell me the CO2 alarms don't really work.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,274
    Location:
    New England
    The critical thing about the alarms is that they should have their trigger wire interconnected, so that if one goes off, they all do. The most reliable way to ensure that works is to use units from the same company. The trigger levels and type may not be compatible if you try to mix and match. I prefer hardwired with battery backup. If you don't have too many power outages, put a lithium backup battery in them, and it should last the 10-years the things are rated before blanket replacement is called for as expressed by the Fire Marshalls Association. Interconnecting them all with the trigger wire adds some wiring complexity, since it obviously needs to run all over the house. It's a good idea to have these on their own circuit so say a hair dryer doesn't trip the circuit and leave you without or running off batteries. Nothing more annoying than the low-battery beep from the things that starts in the middle of the night! As noted, though, if they are infrequent and not too long, the a/c powered units with battery backup, a good lithium battery should last the life of the thing, so this is minimized. I think I've seen some with a rechargable battery, but those don't last forever, either.

    The eariler (10-15 years ago) CO detectors weren't all that great. Read the fine print on them, too, as the sensor may not last forever - 5-years may be close to the life on those, so combining it with a smoke detector would keep the clutter down, but you might want to replace them more often.

    FWIW, if you can find contractor packs of the things, you eliminate the retail packaging, and can get them for about 1/2 of the normal retail pricing, even at the big box stores (HD does carry some in contractor packs).
  3. Master Brian

    Master Brian DIY Senior Member

    Messages:
    368
    Location:
    Kansas
    I have been interconnecting them and I don't see it as much more complex. Just have to run a 14/3 instead of a 14/2 cable and make one extra pigtail connection at each alarm. I guess if I couldn't get to each circuit it might be difficult, but I've found ways to get the wires around.

    I did however install them on the lighting circuit for the downstairs laundry. I didn't figure that would be a common tripped breaker, but one that is used often enough to notice if it lost power. That's what scares me on some "dedicated" circuits. Unless you monitor that circuit, how would you know if it were to trip??

    I have also noticed that the contractor packs are a better deal and have been buying those.
  4. Billy_Bob

    Billy_Bob In the Trades

    Messages:
    422
    I would say that people like you and I who take the care to install smoke detectors and CO detectors all over the place, also take the care to properly maintain things and properly install things and thus will less likely have a problem! :)

    But I feel safer in my house with them. And one time I was running the lawnmower in the back yard with the back door open. The wind was blowing the exhaust into the house. The CO detector went off. So they do work.
  5. iminaquagmire

    iminaquagmire DIY Senior Member

    Messages:
    207
    Smokes

    You need to have one in every bedroom and one in every common area (think hallway) at a minimum. They should also be in utility rooms, laundry rooms, and at the top of the stairwell if its not adjacent to the common area. They should be on the ceiling at the highest part or at least 10 inches from the ceiling if on a wall. Smoke detectors are not all created equal. Combo units are the best bet. You don't want only photoelectric or only ionization as they both detect different types of fires at different rates. Also, even if they are hardwired you should still change the batteries out at least once a year. Its cheap insurance. I would put them on their own circuit. If the circuit is tripped, you will know because they will sound a trouble alarm without power so long as the battery backup is intact. Vacuum your units out when you change the battery. They can clog with dust. I love hardwired units because they don't get taken down when people burn toast and not get put back up.

    CO Detetctors

    One in every common area on every level at a minimum. I like to see them anywhere there is a gas appliance as well. I'd also put one in the major bedrooms. I will say nighthawk is the best manufacturer in my opinion. Their digital readout makes diagnosing problems much easier. They can also datalog previous levels. Adhere to the replacement guidelines as they don't last forever. If there is an alarm, get out and call the fire department. Don't investigate yourself.
  6. Scuba_Dave

    Scuba_Dave Extreme DIY Homeowner

    Messages:
    885
    Location:
    South of Boston, MA
    I bought the Combo CO & SMoek detectors, off **** at almost 1/2 of what HD wanted for a 6 pak
    The ones I bought "talk", they say Carbon Monoxide detected, or "Fire"
    I run 14-3 betweee detectors, no problems
    The one near the stair way I bought one that also has an emergency light

    I thought (maybe only here?) that you could not put them on a seperate circuit
  7. iminaquagmire

    iminaquagmire DIY Senior Member

    Messages:
    207
    Its up to your local building department whether or not they are on their own circuit. Some state that they have to be connected to say a bedroom group so that if the breaker trips, you'll reset it. Either way works as like I said, most will have trouble tones if the hardwire power goes out.
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