Connect 4-wire smoke detector to Elk


Active Member
I have a fairly new 4-wire (red, green, black, yellow) smoke detector left over from my old system - no documentation - that I want to connect to my Elk M1. I see on page 6 of the installation manual that a 2200 ohm resistor needs to be across the terminals that go to a zone. What is the supervision relay and do I need it? How exactly shoujld this be connected?
Someone out there must know how to connect a 4-wire smoke detector? I have no documentation on the smoke detector.
Power from your panel goes to smoke detector power in. Relay coil goes on smoke detector power out. Panel zone wire goes on smoke detector zone in. One side of relay contacts to smoke detector zone out. Other side of relay contacts to one side of EOL resistor. Other side of resistor to other zone out on detector.

If the detector loses power the relay will de-energize and break the loop so the panel no longer sees the resistor. This will cause the panel to show a zone trouble so you know there is a problem with the fire zone.

When the smoke detector is triggered it puts a short across the zone which initiates the fire alarm.
4-wire smoke detectors require an end-of-line power supervision relay (1 per zone) to alert the panel if the detectors stop getting power. It is the coil of that relay that I was referring to.
I checked my smoke detector. It is a Sentrol 449CT. Where do I purchase the supervision relay?