BBB Business Review

How do you wire a 2-wire smoke detector versus a 4-wire smoke detector to a DSC PC1616, DSC PC1832, or a DSC PC1864?


While wiring and programming smoke detectors is relatively simple, it can be kind of confusing at first glance. We will try to simplify things for you to make the process as smooth as possible.

2-Wire Smoke Detectors

Wiring a 2-wire smoke to a DSC 1616, 1832, or 1864 is the easier of the two so we will start there. You will first take the negative wire from your first smoke detector and wire it into the PGM 2 terminal on the main DSC control board. It must go to the PGM 2 terminal and not any other PGM terminal for 2-wire smoke detectors. You will then take the positive wire from your first smoke detector and wire it into the AUX+ terminal on the main board.

If you have more than one 2-wire smoke detector, you will need to connect subsequent smoke detectors in parallel. This means that you will wire the second smoke detector to the first connecting + terminal to + terminal and connecting - terminal to - terminal. The third would wire to the second in the same fashion and so on. On the last 2-wire smoke detector in your line you will put the 2.2k ohm resistor that came with your main board across the + and - terminals.

After hooking in your wires from the 2-wire smoke run; you will need to go into programming by entering *8 + 4-digit Installer Code. You will then see ‘Enter Section’ if you’re using an alpha-numeric keypad. (If you’re not using an alpha-numeric keypad then you won’t see much else but lights. We suggest spending the money and getting an alphanumeric to save some headaches, but it is not required.) Enter into the keypad 009 and that will take you into Section 009 which is PGM programming. For your 2-wire smoke programming you will need to get to the second PGM since that is where is connected. The first 2 digits are for PGM 1. You can leave these the same or program them as needed or if you are not using PGM 1 you can enter 00. The next 2 digits are for PGM 2. Here we will need to enter 04. You can then press # to exit programming. That is all there is to 2-wire smoke detector programming.

4-wire Smoke Detectors

The wiring for the 4-wire smokes is very similar in some ways, but with the actual alarm initiating circuit separated out. You should see 4 unique terminals on the smoke detectors. You may see more, but it is common for there to be 2 terminals labeled +. Besides the + terminal(s) you will have -, NO (normally open), and C or COM (common). On your first 4-wire smoke detector you will wire the + terminal to Aux + on the main board. The - terminal will wire to a PGM terminal. It is common to use PGM 2 here as it gives you a greater current draw than PGM 1, but it is not required to use a particular PGM. Those 2 wires will be your power circuit. The NO and C terminals will be for your alarm circuit. These terminals will wire to a zone terminal and corresponding COM terminal on your main board or PC5108 zone expander.

If you have multiple 4-wire smokes you have a couple options on how to wire them. You can wire second one in parallel to your first smoke detector: + to +, - to -, NO to NO, and C to C. Or you can wire the alarm circuit to a different zone. The power wires can also be home run to the PGM and Aux +. If you have a third 4-wire smoke detector you can make the same choice and so on. This is a big benefit to 4-wire smokes because you can know which smoke detector or detectors are going off or at least potentially narrow it down more than 2-wire smokes.

The last 4-wire smoke detector on each zone will need a 5.6K ohm resistor wired across the NO and C terminals.

The programming for 4-wire smoke detectors is also a little more complicated. You will go into panel programming by entering *8 + 4-digit Installer Code. Assuming you used PGM 2, enter into section 009 as you did with the 2-wire smokes. Again, you will just re-enter the first two digits for PGM 1 or enter 00 if not being used. Next for PGM 2 you will enter 03 to set PGM 2 as sensor reset. If you used a different PGM you will need to go to that PGM and enter 03. The reason you will want to set the PGM that your 4-wire smoke detectors are connected to to sensor reset is because the smoke detectors are latching. This means that once they detect smoke they will stay in an alarm state until the power is turned off to them and then turned back on. Sensor reset does this when you activate the output by entering *72 on the keypad.

Next from the top of programming you will need to go to the zone type programming section for your 4-wire smoke zones: Section 001 (Zones 1-16), Section 002 (Zones 17-24), etc. Each zone corresponds to a 2 digit code, in order. You can enter the other zones as needed and when you get to a zone that needs to be set for fire you will enter 08. 

And finally from the top of programming again, you will also want to make sure the zone is toggled on. You can do this in programming sections 202-209. Section 202 is for zones 1-8, 203 is for zones 9-16, etc. In each section you will see -'s and/or numbers 1-8. If the number is there then the corresponding zone is turned on. You can toggle the zone on and off by pressing the corresponding number. For example zone 17: You would enter 203 and then make sure zone 17 is on by looking for the number 7 and pressing 7 if it is not there.

In summary for 4-wire smoke detector programming you will program the PGM and then program the zone or zones that they are connected to.