Smoke Detectors

tom baker

tom baker

First Chief Moderator & NEC Expert
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Location
Bremerton, Washington
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Master Electrician
Just finished replacing my smoke snd smoke/co detectors with sealed battery ten year lithium, Kiddie is what I used. 120 volt interconnected.
For those wiring houses, is hardwired interconnect required?
Using standard replaceable battery or sealed battery?
It was about $10 more for the lithium version but ten years of 9 volt batteries would be more than that
 
As long as it is not new construction and not commercial, you can use battery only and WITHOUT hardwired interconnect as long as the detectors are listed to be used as such.

Here is what the WAC says about both (see R314.4 & R314.6 W/ exceptions 1 & 2):

WAC 51-51-0314:

app.leg.wa.gov app.leg.wa.gov
 
tom baker said:
I wired mine with 14-3 on a separate ckt. Today I would consider using CCA 14 gage
Click to expand...
It actually better to connect them to a frequently used lighting circuit. If the dedicated circuit trips or gets shut off you may never know until a low battery signal is triggered. That get expensive with the 10Y models since you need to replace the device when the battery is dead.
 
curt swartz said:
It actually better to connect them to a frequently used lighting circuit. If the dedicated circuit trips or gets shut off you may never know until a low battery signal is triggered. That get expensive with the 10Y models since you need to replace the device when the battery is dead.
Click to expand...
I always put them on a lighting circuit that would be a PIA or at least noticeable when Off.
I replaced the 10-year units, when they started failing, with the typical battery backup ones. I thought the lithium units would outlast me. Nope, and it came sooner than I thought.
 
curt swartz said:
It actually better to connect them to a frequently used lighting circuit. If the dedicated circuit trips or gets shut off you may never know until a low battery signal is triggered. That get expensive with the 10Y models since you need to replace the device when the battery is dead.
Click to expand...
Is also one more $50+ AFCI breaker if you put them on their own circuit, if that matters to you.
 
New smoke alarms always require 120v power. They can be interconnected with either wire or wirelessly. They must have battery backup.

The only time that you can go with the battery power only without 120v power is when you are adding the smoke in a remodel situation and you don't have access to get power there without damaging finishes. This is not as clear in the code as it is in the commentary for the code.

Don't forget carbon monoxide detection too... you need one alarm outside of each bedroom group.
 
The combo CO and smokes are nice as they announce what the alarm is, I have one on each floor.
With thr replaceable battery ones, every time I replaced batteries, one would start chirping somewhere, but only at night
 
curt swartz said:
It actually better to connect them to a frequently used lighting circuit. If the dedicated circuit trips or gets shut off you may never know until a low battery signal is triggered. That get expensive with the 10Y models since you need to replace the device when the battery is dead.
Click to expand...
When I wired for smoke alarms in 85, I had a relay that would connect to my X-10 system and flash house lights, so I used a separate circuit. Curt might know what X-10 is.
 
curt swartz said:
It actually better to connect them to a frequently used lighting circuit. If the dedicated circuit trips or gets shut off you may never know until a low battery signal is triggered. That get expensive with the 10Y models since you need to replace the device when the battery is dead.
Click to expand...
I agree it's better to put the smokes on with another circuit. But if on their own circuit and the circuit trips, or is turned off, the smokes will work on battery but you still get a chirp every minute or so telling you they lost power. Only way to stop the chirping is to either turn the circuit back on or take the batter out.
I found this out when wiring a new house. The circuit was turned off and the smokes were wired into that circuit. The HO asked why the alarms were chirping. I saw the green light on the alarm was not on so I turned the breaker back on and the chirping stopped.

I can't say all the different brands work this way, but the brand I was using did.
 
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