What are Power-Limited Fire Alarm System Cables

Currently there are three types of power limited fire alarm cables in use but before we get to those let’s touch on National Electric Code (NEC) article 760.

NEC Article 760 covers the installation of wiring and equipment of fire alarm systems including all circuits controlled and powered by the fire alarm system. These systems are defined in the NEC as the portion of the wiring system between the load side of the overcurrent device or the power limited supply and the connected equipment of all circuits powered and controlled by the fire alarm systems.

To comply properly with article 760, selecting the right cable for your fire alarm installation sounds like half the battle. Let’s check out the first of our three cables.

1) Type FPL – This type of power-limited fire alarm cable is listed by the NEC as being suitable for general purpose fire alarm use. This list “excludes” installation in riser, ducts, plenums and other space used for environmental air unless the cable is installed in conduit. All FPL cables are listed as being resistant to the spread of fire and must pass both UL test 1424 and the vertical flame test UL 1581.

2) Type FPLR – This type of cable is listed as being suitable for use in a vertical run in a shaft or from floor to floor. All FPLR cables are listed as having fire-resistant characteristics capable of preventing fire from traveling from floor to floor. Riser cables must pass both UL test 1424 and vertical riser test UL 1666.

3) Type FPLP – The FPLP rating is suitable for use in ducts, plenums and other space used for enviromental air. All FPLP cables are listed as having adequate fire resistant and low-smoke producing characteristics and must pass both UL test 1424 and UL stiener tunnel test 910.

Here’s a quick look of a FPLP cable from our YouTube Channel.

Now that you have a better idea on which cable may be a better fit for your installation let’s check out section 760-71 of that National Electric Code that specifies where Power-Limited circuit conductors are to be installed.

– Installed in raceways or exposed surfaces

– Protected against physical damage

– In metal raceways or rigid non metallic conduit where passing through a floor or wall to a height of 7 feet above the floor, unless adequate protection can be afforded by the building construction.

– In rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit or electrical metallic tubing where installed in hoistways

These cables are power limited for 300V and power limited is inherently limited by the power supply of the transformer and other power supply devices. You’ll also notice that some cables offer a shield for protection against interference created from other cables or other electronic/electrical and mechanical devices and the shield is a 100% Aluminium foiled wrap.

If your new to fire alarm cables this is a good start and you should read the entire NEC article 760 so your install is correct the first time.