There are many different kinds of fire alarm cables currently in use today. Each kind meets specific needs, and they can be broken into larger categories and subcategories. The broad range of different kinds of fire alarm cables ensures that each building or structure receives a specific kind of fire alarm system, customized to take all kinds of hazards into account.
A power limited fire alarm cable is one of the main categories of cable. This kind of cable is run through enclosed tracks or tubes. By law they are not allowed to extend more than 10 feet (3.048 m) outside of an enclosure. There are three main kinds of power limited fire alarm cables in use today.
A fire power limited (FPL) cable is a type of fire alarm cable that is commonly used and suitable for most applications. These cables are not allowed to be used in vents, ducts or other air passageways. Fire power limited plenum (FPLP) cables are a form of fire alarm cable designed for use in air passageways between rooms on a floor. Fire power limited riser (FPLR) cables are power limited cables that run vertically between floors.
The other major classification of fire alarm cables is non-power limited cables. There are two main types of these. Non-power limited fire alarm cables (NPLF) are general use cables, suitable for most forms of installation. There are also the non-power limited fire protective (NPLFP) cables which are suited for use in air passageways.
FPLPs can be classified further depending on the material they use for insulation. They can use either a fire and smoke retardant form of PVC or a flouropolymer based insulation. If an FPLP also complies with the regulations for limited combustibility as established in the U.S. by the National Fire Protection Association, it may be classified as “limited combustible.”
Some fire alarm cables may not be shielded at all. These can be either a power limited fire alarm cable or a non-power limited fire alarm cable. Unshielded fire alarm cables are usually located within the fire alarm itself and may connect the alarm to the warning siren. These cables can be damaged in a fire which accounts for their limited use. It is acceptable to use them on the alarm itself since the alarm would have sounded before this happened and would still be sounding on other alarms attached to the system.
Due to the large number of ways in which a fire may threaten a structure such as a house or business, there need to be different ways of making sure that the warning is conveyed to people in the area. These specialized cables ensure that the warning system is not damaged by the fire itself. Knowledge of how a fire progresses has led to the development and implementation of these specialized lifesaving devices.