5.3 Fire Alarm Cable Types, Plenums, Risers, and Abandoned Cable

Fire alarm cable is not "low-voltage wire." The jacket marking tells you whether the cable is listed for power-limited or non-power-limited fire alarm use, and whether it may occupy a plenum, a riser, or only general-purpose space. Independent OpenExamPrep study material that helps candidates prepare for the NY DOS Security or Fire Alarm Installer exam treats those markings as field language you must read on the reel, not as decorations.

Typical PLFA markings

For power-limited fire alarm (PLFA) circuits, the markings you will see on jackets and cut sheets are:

• FPL — general-purpose power-limited fire alarm cable. Not a riser listing. Not a plenum listing.
• FPLR — power-limited fire alarm riser cable. For vertical runs in shafts between floors, as generally taught.
• FPLP — power-limited fire alarm plenum cable. For spaces used to transport environmental air.

Typical NPLFA markings

For non-power-limited fire alarm (NPLFA) circuits the parallel family is:

• NPLF — general-purpose non-power-limited fire alarm cable
• NPLFR — non-power-limited fire alarm riser cable
• NPLFP — non-power-limited fire alarm plenum cable

The "P" is plenum. The "R" is riser. There is no "P means power." Power-limited versus non-power-limited is the FPL versus NPLF prefix. Using NPLFP on a PLFA circuit, or FPLP on an NPLFA circuit, is the wrong family even if the space rating looks impressive.

Substitutions

The substitution rule the exam likes is directional. Plenum-rated fire alarm cable may be used where riser or general-purpose fire alarm cable is allowed. Riser-rated cable may be used where general-purpose is allowed. You do not substitute downward into a more severe space. FPL does not become legal in a return-air plenum because the run is short. FPLR does not replace FPLP in an environmental-air plenum because "both are fire alarm cable."

Some communications listings appear on 760 substitution lists in trade teaching. That is still a 760 substitution question, not a free pass to install CATV plant as a notification circuit. When in doubt on this exam, choose the fire alarm marking that matches the space: FPLP or NPLFP in a plenum, FPLR or NPLFR in a riser, FPL or NPLF only in general-purpose space.

Circuit-integrity cable (preview)

Circuit integrity (CI) cable is listed to continue functioning during fire for a specified time, commonly taught as a two-hour survivability tool. Jackets may read FPLP-CI, FPLR-CI, or similar. CI is about pathway survivability — keeping notification, firefighter communications, or similarly critical circuits alive while the building is under fire attack. It is not the same thing as a plenum smoke rating and not the same thing as a two-hour fire-rated shaft. A later chapter on pathways and survivability covers when CI or a two-hour enclosure is the method. This section only requires you to recognize CI as a survivability listing, not as a substitute for choosing FPLP in a plenum.

Plenums versus two-hour risers

An air-handling plenum is a space that transports environmental air. Typical examples are a return-air cavity above a hung ceiling, and ductwork used as an air path. Cable in that space must be listed for plenum use (or installed in a method 760 treats as acceptable in plenums). Plenum listing is a low-smoke, limited-flame jacket listing so a fire in the air stream does not send ordinary-cable smoke through the building. Not every hung ceiling is a plenum. If the cavity is not used for environmental air, it may be ordinary space for cable-listing purposes. If the mechanical drawings and the AHJ treat it as a return-air plenum, it is a plenum — even when the room below is only a corridor.

A two-hour fire-rated riser or shaft is a construction assembly. It is a vertical opening protected by fire-resistance-rated walls, not an air-handling cavity by definition. Cables in a rated shaft still need the correct riser or plenum cable listing for that occupancy of the shaft. Separately, if the pathway must survive fire for occupant notification, you may need CI cable or a two-hour protective enclosure — a survivability choice, not a plenum choice.

Do not answer "use two-hour riser cable" when the stem describes a return-air plenum. Those are different occupancies of space. Do not answer "FPLP" when the stem is a wet underground duct just because FPLP sounds like the most serious marking on the reel.

Abandoned cable

Abandoned fire alarm cable in accessible locations — including accessible ceiling cavities — is generally taught as cable that is not terminated at equipment and not identified for future use. Accessible abandoned cable is to be removed. Leaving a dead pair in a plenum adds fuel and smoke. Tagging a spare, identified for future use, is the usual teaching exception; unlabeled leftovers are not "spares." Cut ends stuffed above tiles are still accessible abandoned cable if someone can reach them from the occupied space by lifting a tile.

Support, not the ceiling grid

Suspended-ceiling grids are not a wiring method. Do not drape fire alarm cable on the grid, and do not treat the tile as a shelf. Support cables independently with listed straps, hangers, or independent support wires identified for cable support — not the wires that only hold the ceiling. Independent support is still required in a plenum. Plenum listing answers smoke production; it does not answer sagging cable on tiles. A neat J-hook path that never rests on the grid is the picture the exam wants. A "temporary" loop laid on the tiles until the painter finishes is still using the grid as a wiring method.

Grounding

Metal raceways, metal cable armor, and metal equipment enclosures used on fire alarm work are grounded. Provide an equipment grounding path back to the electrical system as generally taught for metal wiring methods. Do not use earth or a sprinkler pipe as the equipment-grounding conductor. Shield drain wires terminate per the listed equipment instructions; that is signal reference, not a substitute for raceway grounding. The 120-volt supply to the control unit carries its own equipment-grounding conductor on the Chapter 3 side of the job. Bonding bushings, jumpers, and listed fittings exist so the metal path is continuous through boxes and concentric knockouts.

Wet, damp, and dry listings are not plenum listings

Dry-location cable belongs indoors where it is not subject to moisture. Damp locations (some basements, protected outdoor overhangs) and wet locations (underground, outdoors exposed to weather, slabs on grade, wash-down) need cables listed for wet (or wet/damp) use. FPLP is a fire/smoke listing for plenums. It is not automatically a wet-location listing. An underground notification run in a wet duct needs a wet-listed method even if you correctly refused FPLR. Outdoor weatherproof horns do not make indoor-only cable legal on the wet side of the wall. Read both listings: space (plenum/riser/general) and wet/damp/dry.

Worked example: FPLP versus FPLR above a corridor

A listed PLFA notification circuit will serve horn-strobes in a corridor. The cable will be pulled in the space above a hung ceiling. The mechanical drawings show that cavity as a return-air plenum serving the corridor.

Step 1 — Classify the circuit. Listed PLFA source → PLFA family → FPL-type markings, not NPLF.

Step 2 — Classify the space. The cavity transports environmental air. That is a plenum occupancy, not a riser occupancy. A corridor on the floor below does not make the ceiling a riser. A riser is a vertical shaft between stories. A two-hour shaft somewhere else in the building does not change this ceiling's air-handling use.

Step 3 — Choose the marking. FPLP is the PLFA plenum marking. FPLR is a riser marking and is not the listing for an environmental-air plenum. FPL is general-purpose only.

Step 4 — Substitution check. FPLP may also be used in riser or general-purpose space, so using FPLP through a later shaft is acceptable. The reverse is not: you may not leave FPLR in the plenum because the cable later drops down a riser.

Step 5 — Install hygiene. Support the FPLP off the grid. If a previous contractor left an unterminated, untagged fire alarm pair in that accessible plenum, remove it as abandoned cable. Ground any metal raceway used on the same circuit. If the pathway later needs two-hour survivability, that is a CI or enclosure question for the survivability chapter — it does not change the plenum marking required today.

If the same corridor ceiling were a non-air-handling cavity (a ceiling that is not used as a return-air plenum), FPLR or even FPL might be the space listing, depending on whether the run is a riser. The stem's "return-air plenum" is the hinge. Independent OpenExamPrep teaching stops at that hinge. Read the jacket; read the occupancy of the space; do not drape the cable on the tiles.