Smoke Detectors, 2-wire vs. 4-wire

rcharris

Member
Hello All:

I need to start pulling wire for smoke detectors (retro-fit) in my home. These will be connected to an Elk M1G. I will have a total of 6 now and possibly up to 8 down the road.

What are the trade-offs of 2-wire versus 4-wire detectors? Are there any specific brand and models that you all can recommend?

thanks for the help!

Regards,
Rod
 
2 Wire Smokes:
System Sensor - 2Wxxx series
Compatibility ID: A

4 Wire Smokes:
System Sensor
GE
or anyones will work that uses 12 VDC.
 
My personel choice was 4 wire so I could have them on seperate zones to take advantage of the Voice announcement features of the M1. My panel will announce where the detector is that tripped. I have about 7 zones for smokes and a few for thermals (overkill but nice). If one goes off I know where it is without going to a keypad.

I did the same with CO Detectors, flod detectors (as a non alarm zone) and some day as time and money permit more "toys".

There are many good smoke detectors out there. For the 2 wire you need to use those recommended by the manufacturer (and you cannot ever mix the 2 wire detectors). For the 4 wire any 12 Vdc detector would do and you can mix them. Some have built in sounders and or thermals as well (the sounders would make them a bit more pricey).

I used the system sensor 4W-B which are photoelectrics which are less likely to false alarm but some people like ionization detectors better.

Caddix also makes wireless smokes that work with the wireless receiver that is recommended for use with the ELK panels. I used one where I forgot to run wire to and didnt want to rip out the sheetrock to get there.

I admit I bought my detectors via EBAY and was careful who I bought them from and always made sure when they were received that they were indeed brand new. I got some good deals on lots of devices that way.
 
Don't forget the 2-wire smokes have the "clean me" feature that shows up on the keypads. Then, you do a visual search of the smokes to find the dirty one.
 
Thanks for all the response:

Let me see if I can summarize this:

If one uses 2-wire smokes, then they can only go on zone 16, and there is no way to tell from the Elk end of things which one alarmed?

The 4-wire can all be wired to separate zone inputs (a plus) but they will all have to be powered by the switchable power +SAUX to do verification? This will also use up more inputs.

4-wires require an EOL Relay, and don't have the "clean-me" support that is possible with System Sensor 2WT series, (with accessory module)

The 4-wires seem to cost a bit more.

Are there any other significant differences? Is one type more inherently reliable? durable? cuter? :)

Are the Caddx wireless reliable? do they require annual battery replacement?

Again, thanks for the input
-Rod
 
The system sensor 2WB and 4WB are almost identical in appearance. They are a popular detector but there are many good detectors out there but for 2 wire the system sensors are what ELK recommends (due to extensive testing). I beleive that they plan on testing other models in the future (its a long process).

The caddix use Lithium batteries I think which should last a few years.

The relays arent cheap either!

Its what you prefer and what your budget will allow.
 
If one uses 2-wire smokes, then they can only go on zone 16, and there is no way to tell from the Elk end of things which one alarmed?

The detector that triggered the alarm will have it's red light illuminated during the alarm condition, so you can tell by visual inspection.

4-wires require an EOL Relay, and don't have the "clean-me" support that is possible with System Sensor 2WT series, (with accessory module)

Correct, and the 2-wire ones require an EOL resistor on the last detector (the one that comes with the Elk). A note on the 'clean-me' support, I tried setting that up (the 2W-MOD2) when I put my last detector in, and it appeared to work (walk test worked, indicators were correct) but I got some false alarms. I also had added the RRS-MOD as well. I have since taken them out and have not had any so far. Mind you, my issues may be the result of an issue of my own doing. I'm not done yet with it.

I have 5 of the 2WTAB detectors with integral sounder in right now, and aside from the issue above they have worked fine (I had 4 of them in for about a month for before adding the 2W-MOD2). When I had the false alarm, I was briefly wishing I had a log of which one was triggering it. I had a theory that you might be able to run a wire from the remote annunciator outputs on the 2WTAB to inputs on the elk to get 2-wire smokes and get an indication on the panel which one triggered it, but I've had enough fun so far with accessories and am still working on my basic install so have not given it much thought.

The 4-wires seem to cost a bit more.

Depending on the wire you get, 4 wire could cost you more there as well (remember the discussions on firewire). That's not including the EOL relay (which from earlier posts were $12-$20 I think).
 
rcharris said:
4-wires require an EOL Relay, and don't have the "clean-me" support that is possible with System Sensor 2WT series, (with accessory module)
According to my last discussion with ELK tech support there is no need for an accessory module for the M1 to use the "clean me" feature. The M1 goes into trouble and the keypads read "Clean Me Det". You then do a visual of each detector and the red led on the detector should show which one needs cleaning. Anyone correct me if I'm wrong. I'd like to know since I'm doing a 2-wire smoke install this weekend.
 
The M1 goes into trouble and the keypads read "Clean Me Det". You then do a visual of each detector and the red led on the detector should show which one needs cleaning.
If this is true then I am leaning towards 2-wire:

Advantages:
Slightly lower detector cost
Lower wire cost
No end of line relay, just a resistor
Only uses one zone (and I kept zone 16 open just in case)

Drawbacks:
Not knowing explicitly which detector caused the alarm without walking around.
Limited to certain approved models.

Thanks
-rod
 
rcharris said:
The M1 goes into trouble and the keypads read "Clean Me Det". You then do a visual of each detector and the red led on the detector should show which one needs cleaning.
If this is true then I am leaning towards 2-wire:
I just spoke with Brad at ELK. My recollection was correct. Everything I wrote in my earlier post about 2 wire System Sensor detectors is correct.
 
That is surprising, I wonder if this is new (the elk supporting the cleaning signal from System sensor detectors). I thought when this was reviewed a few months back, the clean me signal was only supported by GE (I think) models (clean-me is proprietary from how I remember it).

Guess I have no need to worry about the 2W-MOD2 anymore....
 
what are these relays called and where can i find them online does someone know please?
another question what is the "clean me" feature is it like a sensor for when it cleaning like in removing dust and wiping or what it means?
 
Please be aware that you posted to a thread that is over six years old! Things may have progressed over time.
 
Pull a four and use two and you can't go wrong. After all nobody looks at a wire coming out of the ceiling and says "damn, it has to many conductors"

Sent from my Galaxy Nexus using Tapatalk 2
 
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