Short for Security Industry Association. Also refers to a communications protocol used by alarm panels to transmit events over a standard POTS line.
SIGNALLING LINE CIRCUIT (SLC) or DATA COMMUNICATION LINK (DCL) The means employed by an ADDRESSABLE type control panel to communicate with compatible devices in the field. These may include INPUT DEVICES, OUTPUT DEVICES, ANNUNCIATORS, and remote TRANSPONDERS.
SIREN/BELL : This is an OUTPUT DEVICE installed at the protected premises to audibly signal an alarm to the building's occupants.
SMOKE ALARM : A combined smoke detector and audible alarm device designed to sound an alarm within the room or suite in which it is located upon the detection of smoke within that room or suite. There are two different types of sensing technologies utilized: photoelectric and ionization (with photoelectric being preferable in most residential settings).
SMOKE DETECTOR : This is an INPUT DEVICE used as part of a FIRE ALARM or SECURITY SYSTEM to sense the presence of smoke and products of combustion. There are two different types of sensing technology utilized: photoelectric and ionization (with photoelectric being preferable).
STANDPIPE SYSTEM : An arrangement of dedicated piping, valves, hoses and associated equipment installed in a building with the hose connections located in such a manner so as to facilitate controlling (or extinguishing) a fire. Only individuals trained in its use should operate this type of equipment.
STI : Speech Transmission Index - a measure of a sound system’s intelligibility.
STROBE LIGHT : An OUTPUT DEVICE that employs an intense pulse of visible light to alert the building's occupants to an alarm, trouble or fault condition.
SUPERVISED : A term which refers to an alarm circuit that when cut or tampered with will initiate a fault or trouble signal to alert the building occupants.
SUPERVISORY FAULT (or SUPERVISORY SIGNAL) : Refers to a condition in which a device supervised by a fire alarm system is moved from it's "normal" state such as would be the case when you close a "normally open" sprinkler valve, or the air pressure in a sprinkler dry system falls below a pre-set level, or the power is interrupted to a sprinkler heat trace controller (these are only three examples of supervisory type signals). In many jurisdictions supervisory signals must be "latching" (that is where a return to the "normal" condition for the supervised device must be followed by a systemwide RESET). A supervisory fault (or signal) is different from a "COMMON TROUBLE".
SWINGER : In the security alarm industry, this is a fault on a communicator zone usually attributed to a malfunctioning field device or relay that ultimately causes a large number of the same signals to be transmitted to the central monitoring station. Also called a nuisance alarm.
SWINGER SHUTDOWN: Is a programmable feature of most modern alarm communicators enabled by an installer to limit the number of events transmitted on a specific zone or circuit during either a twenty-four hour period or an ARMED cycle. Normally this is utilized to prevent repeated false signals being sent to the central station from a defective field device or common service issues like a loose door contact or an intermittent connection in a sensor. The more common setting is three "events" in a twenty-four hour period. Multiple alarm trips from a device (or zone) is called a "swinger" and when you get dozens of events in a short period the station may also refer to the account as a "runaway". Fire alarm communicators cannot employ SWINGER SHUTDOWN and technicians performing annual testing of monitored fire alarm systems should be confirming this. You can read more about the procedure in our TIPS section.