smoke detector interconnection

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  #1  
Old 04-06-06, 02:48 PM
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How is the trip wire on hard-wired smoke detectors typically connected?

Is it of a particular gauge? I presume it's a low-voltage wire, right?

Thanks,

Antun
 
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  #2  
Old 04-06-06, 03:09 PM
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Antun,

I made a new post for you. Please start a new post when your question is new.

No, smoke detectors are interconnected using three conductor cable. This means they are all on the same circuit, using either 14-3 or 12-3.
 
  #3  
Old 04-06-06, 03:34 PM
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OK - thanks. I was not sure if it was more convenient to continue on a similar thread but I'll start new threads in the future.

Does that mean that I use 12/2 cable (or 14/2 if appropriate) to go from the circuit breaker box to the first smoke detector?

-Antun
 
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Old 04-06-06, 04:33 PM
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right
the source from the panel would be a 2 wire.
The practice [now required] is to tie the circuit for the smokes to some annoyance load that you will IMMEDIATELY notice doesn't work [so you know the power failed]
and since you are going to the bedrooms [if you are thorough] use an arc-fault breaker for the circuit, as well.

regards
 
  #5  
Old 04-06-06, 04:45 PM
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Thanks - I called the city and they confirmed the detectors need not be on their own circuit. There's a general lighting circuit *right* next to where I want to place them, so I'll use that.

I guess I'll have to replace the breaker with the arc fault one. Is that all I have to do for the breaker?

-Antun
 
  #6  
Old 04-06-06, 08:20 PM
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Originally Posted by antun
Thanks - I called the city and they confirmed the detectors need not be on their own circuit. There's a general lighting circuit *right* next to where I want to place them, so I'll use that.

I guess I'll have to replace the breaker with the arc fault one. Is that all I have to do for the breaker?

-Antun
Sounds like we have two different methods (dedicated circuit vs. shared circuit).

The shared circuit makes sense from a safety standpoint. I'll add one more question. I've got an attached garage that contains the washer/gas dryer, gas water heater, and nothing else. The garage is not used for a car, just storage, etc.

When I wire up my interconnected fire/CO alarms, I plan to have the first one in the series in the garage, then move into the house.

I don't see any reason why this would cause an issue, and I've been trying to think of a possible way that the alarm in the garage could sound in error, but can't come up with one.
 
  #7  
Old 04-06-06, 08:44 PM
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Originally Posted by fuente
Sounds like we have two different methods (dedicated circuit vs. shared circuit).
Where did you see dedicated circuit?


> I've got an attached garage that contains the washer/gas
> dryer, gas water heater, and nothing else.
> When I wire up my interconnected fire/CO alarms, I plan to
> have the first one in the series in the garage, then move into
> the house.
>
> I don't see any reason why this would cause an issue, and
> I've been trying to think of a possible way that the alarm in
> the garage could sound in error, but can't come up with one.

I can. Close proximity to a clothes dryer can result in a false alarm from moisture and dust as with a bathroom.

But this affects only placement of the SD. The order in which you connect them makes no difference.

I like to start from a the circuit lighting a dark hallway or stairwell where lights are likely to be used and preferably this circuit has no receptacles.

Yes, the signal wire is high impedance / low voltage, but there is no problem with running it as the third conductor.
 
  #8  
Old 04-06-06, 08:53 PM
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oops my bad. It said need NOT be on a dedicated circuit..

yeah I know the order doesn't matter, but the circuit would be coming from the panel in the garage into the house, so I could hit the garage detector.

I think it would be valuable to have one in the garage, so I'll just put it away from the dryer. Thanks bolide.
 
  #9  
Old 04-07-06, 01:04 AM
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Antun & all,

Be carefull, just because YOU don't put a car in the garage the inspector(fire) may not see it that way, They often look at potential or intended use. Some areas will require a heat det. interconnected in that area on battery back up. Check into Photo elec and Ionization smokes to find the one that best fits the needs of the area. CO detectors will soon follow..... 3/31/06 In Ma are now required on all floors and outside bedrooms. In all dwellings with fossil burning fuels or inside attached parking areas. It's comming to all.
 
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Old 04-07-06, 06:07 AM
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what about gas alarms, etc?

Maybe I haven't looked enough, but are there gas alarm heads for simple interconencted detectors like this? I've seen both kinds of smoke and combo smoke/CO, but no gas. Since I have an all-gas house, for CO detectors I use combination units that also do gas. I'd like to add interconnected, but probably not when I need to have other detectors around anyway.
 
  #11  
Old 04-08-06, 09:07 AM
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I have heard of jurisdictions requiring smokes to be placed on dedicated circuits, and also heard of different jurisdictions requiring them to be on circuits that would definutely be missed if de-energized. Check with your local building department for details.

If you're under the 2002 or 2005 NEC, then you must AFCI protect the circuit feeding a new outlet in a bedroom, so you'd need to AFCI protect the circuit supplying the new smokes. Just swap out the breaker as you guessed.

Firex may make gas detectors that interconnect with their smokes, you'd need to check with your local supply house (maybe a box store would carry some, but I doubt it.) They'd likely need to be special ordered.

Interconnecting would be a good idea, because if you have a large house, and the gas leak occurs at night, your smokes would go off with the gas detector, alerting you to the danger in time to do something about it.

Firex recommends heat detectors in the garage, I'm not sure if a CO or smoke detector would be a good idea, as they'd probably tend to nuisance alarm like crazy. I've never installed anything in the garage, it's not a requirement in my area.
 
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