BBB Business Review
Smoke Detectors

Smoke Detectors

2-wire and 4-wire smoke detector varieties can be used with any hardwired alarm system. 2-wire smokes use just two wires for data and power and must all be chained on the same run. 4-wire smokes use separate two wire pairs for power and zone data and can be separated on their own zones.

More About Smoke Detectors

All of the hardwire alarm systems we sell can accept either 2-wire or 4-wire type, but there are some things to keep in mind when making this decision. A couple of things are:

1. Generally speaking, you are limited to a maximum of about 12 2-wire smokes per system (the exact amount is determined by loop resistance). Whereas the 4-wire type allows you to have many times this amount, only limited by the current available from the board or power supply.

2. The 2-wire type offers full supervision of the line between the panel and smoke, whereas the 4-wire type only supervises the detection circuit by default. 2-wire type smokes are the latest technology, however, the 4-wire type are the universal standard and should be used when in doubt.

There are different styles of 2-wire and 4-wire smoke detectors. If you need a simple smoke detector then we carry those in the 2W-B and 4W-B models. There are also the 2WT-B and 4WT-B models which are a combination of smoke and heat detector. Then there are the 2WTA-B and 4WTA-B models which are detectors that combine smoke and heat as well as a built-in sounder for local notification of emergency.

We also carry the System Sensor COSMO2W and COSMO4W model smoke detector combined with a carbon monoxide sensor. These smoke / CO combination units use an intermediary module that goes between the detector and the panel called the COSMOD2W and COSMOD4W respectively. The modules connect to the system to separate the smoke and CO zones, and the COSMO units are run in a chain from the module. The COSMOD modules can also operate the 2WT-B or 4WT-B model smokes allowing you to chain a variety of coverage on one smoke run. 

Not only do we carry the 2-wire and 4-wire smoke detectors but we also carry accessories for them. For the smoke detectors that contain sounders, we carry the System Sensor RRS-MOD Reversing Relay and the DSC PRM4W. These relays will set off sounders in all the other smokes in the line if one is triggered.

We also feature power supervision relay models DSC RM-1, DSC RM-2, and SYS-EOLR1. These supervise the power of smokes and will make you aware if the smokes lose power or the line is cut.

And lastly, we carry canned smoke for you to use to test your smokes after installing them. When testing smokes, be sure to have a method of clearing the smoke (such as canned air) from the detector so you don't have multiple alarms triggered during a single test.