Question regarding my System Sensor 4W-B

Okay, so I’m in need of some advice for those who own System Sensor i3 smoke detectors, preferably the 4 wire version, which I just purchased used, so I don’t have the data sheet for it. My question is: Can you wire up a 4W-B using only 2 wires or not? For the record, it will be running off a 24 VDC power supply, as I don’t really see the need for a panel for my purposes. There are 5 terminals on the detector, and I’d like to hook it up to the power, and to 2 notification appliances. At this moment I do not believe I have to hook it up to my silence switch (just a light switch), but maybe I do. For the record my system setup will be as follows:
2 notification appliances wired to go off together with the activation of either initiation device (the smoke detector and the pull station) and the silence switch will silence both notification appliances. I assume you just wire it like you would with 2 pull stations, but if I’m wrong, any help would be nice. Unfortunately my power supply won’t get to my house until Saturday, but everything else gets here today. I’m just going to experiment with the schematic for now though. Any help would be appreciated. Thanks.

There’s a good diagram of the system wiring available at the bottom of page 2 in this manual: System Sensor | Honeywell Building Technologies

You will need four wires running to the device, two for power and two for the contact on the detector. The power feeds connect to the IN/OUT terminals, and you will want to be able to temporarily cut this power in order to reset the detector. The wiring for the contact will pass through the NO and COM terminals.

Thanks for the help!

I expanded on Nick’s nice drawing to be more specific to your question. Add up the current draw on the notification appliances you plan to use to be sure they total 0.5 amp or less. That is the contact rating on the 4W-B.

Thank you. While I was making the drawing I forgot he wasn’t using a panel.

So I can’t use my 2901-9846 and 4903-9105 strobe plate and my Cerberus Pyrotronics MC-S17-S? Because the -9846 is .065 amp and the 9105 is like 200mA or something…and I don’t know that the other one is…but it’s a 4 wire alarm…I’ll look when I have time (I have the data sheet).

Unless you mean the contact rating is 0.50 amp, because that would make more sense.

0.5 amp = 0.50 amp = 0.500 amp = 500 ma = 1/2 amp. They are all the same.

00.200 A = 200ma
+0.065 A = 65 ma

=0.265 A = 265 ma which is less than 0.5 amp.

Thanks for the clarification! I just got my power supply so hopefully I’ll get a test of it done soon.

Here is another possibility. Add a relay to the circuit to control the NA load. This takes the NA current load off of the internal contact in the 4W-B and the manual station. The maximum NA current is now controlled by the relay contact rating and how much current the power supply can produce. Might want to consider adding a fuse to protect the power supply against overload.

I’m thinking about adding something to protect from overload, but it’s plugged into the outlet on my furnace which is a GFCI outlet. I do have a three prong plug for it too so it will be grounded. I may add a surge protector/power strip in the future though, although I might end up using the first diagram since my Pyrotronics horn strobe came DOA (the strobe works, but the horn is broken).

Send me a PM and we’ll see if we can get it working.

Sorry for bumping this, but it’s my own thread and I had a question again. If I hook the negative from the power into one side of the IN/Out terminal and the negative from the NACs on the other side of the terminal, would it still work or would I have to use 3 wires and connect them separately (I.e. Using a wire nut to connect the 3 wires or could I eliminate this step by using two wires as I mentioned above)? Or would that short circuit the detector?

You can connect the negative side of all the devices together any way you want to. They are all common at the same potential so using the negative SD terminal as a tie point will not cause a problem. The drawing is done in a way that makes it clear what connects together.

Ok. That’s what I thought; thanks!

Ok ladies and gents,

I need help badly.
I charter school with no money asked for help after their FACP caught fire. It was an NX8CF panel now is a 9050UD
With 4 wire smokes.
I’m putting MMF-301’s at every existing smoke and pull station until the raise enough money to do a complete upgrade to fully addressable brand new.
My question to you all is how do I reset power to these smoke detectors? I also have an existing altronix AL300ULXB on site that I will use if I can. I’m 35 hours deep in 2 days and can’t see the Forrest through the trees anymore. I know someone can help get this done tomorrow.
Thank you

Greetings all. I have an old Ademco 623m12 smoke detector that is integrated into my security system. I broke the clip that holds it to the mounting plate and I’m trying to wire a System Sensor 4w-b replacement. The system is low voltage. The old detector has a 12 pin connector with 4 wires leading into it and I’m going to have to clip off the connector and connect the wires it to the terminals on the 4w-b.

I’m not an electrician so reading a wire diagram is confusing. Basically, I have the following wires:


Can some tell which wire should be connected to which terminal on the 4w-b? The old detector does NOT produce sound - when it’s activated, an alarm is produced via my security system. Also, the old detector is the last detector in a “chain” of 2.

Thanks you - any help would be appreciated. I have 4 pictures and can only one picture per post so should I reply to my own post the other 3?


Not sure if that would work but I’d wire it up that way:

(left side is from the 623-12 harness, right the i3’s terminals)

  • red wire → i3 positive terminal

  • black wire → i3 negative terminal

  • contact terminal #1 (purple wire) → i3 “NO” terminal

  • contact terminal #2 (white/red wire) → i3 “COM” terminal

Let me know if that works :blush:

(on a random tangent, I have the same detector, although yours looks to be slightly newer than mine is!)

Thank you so very much! Since there are 2 positive terminals on the i3, I assume it doesn’t really matter which one I use?

Google said Ademco was acquired by Honeywell, so I called them and they suggested this i3 model should work, but their support could only send me the wiring diagram, which didn’t help a newb like me.

I will try it and respond here - might be a little while though. Thanks again!