A common wiring pattern for smoke detectors is to run a 2-conductor cable, such as 14/2, from the breaker panel to first smoke detector and then 3-conductor cable from each detector to another onward. The third wire is for tripping all of the detectors should one detect smoke.
Which type of cable is used for fire alarm system?
BS 7629 – 1, 300 / 500 V fire resistant electric cables with non corrosive gases and low emission of smoke when affected by fire. Category STANDARD 30 & STANDARD 60 when tested in accordance with BS EN 50200-Method of test for resistance to fire of unprotected small cables for use in emergency circuits.
What size cable do I need for a fire alarm?
“Total cable length between alarms must not exceed 250m (273yds) and be 1.0mm in diameter, 3 core and earth (BS6243Y). Wiring must conform to the IEE regulations – BS7671, or latest edition.”
How many types of fire alarm cables are there?
Fire alarm cables are placed into three broad categories: plenum, non-plenum, and riser. Each of these corresponds to another standardized category, and these terms reflect where the fire alarm cable can be installed safely. Plenum cable, to be used in ducts or other enclosed air spaces, is called FPLP.
Can you join fire alarm cable?
Did you know you can’t connect a fire alarm to just any kind of wiring? Fire alarm cabling needs to be compliant with British Standards; otherwise if something happens within the cabling it could create a fault in the fire alarm.
What is shielded fire alarm cable?
FPLR shielded fire alarm cables include an aluminum polyester foil shield over the conductors to protect against interference. A foil shield is the only type of shield offered in standard riser alarm cables.
What is the difference between 2 wire and 4 wire smoke detectors?
Differences. The key differences between two and four-wire systems are the numbers of wires and how the wiring is connected to the control panel to trigger the alarm. A four-wire system has separate wires, while a two-wire system uses the same wires to power the unit and to trigger the alarm.
Do smoke detectors need to be grounded?
If it is metal, code requires that the box be grounded. If all the external parts of the smoke detector are plastic then a ground is not required (the same is true with light fixtures).