Fire alarm cable types: FPL, FPLR, FPLP, 14/2 and when each is used

The table summarizes the UL product standard's scope in our own words. The installation rules for each space sit in NFPA 70 Article 760, below.

Select fire alarm cable in three passes: route suitability, circuit survivability and electrical compatibility. A jacket color or conductor size does not settle all three.

This guide uses NFPA 70 (2020) for NEC navigation, matching NICET's cited Level II reference list. Use the edition enforced by the AHJ on an actual project; do not transfer section numbering into another edition without checking it.

FPL, FPLR and FPLP

The three markings identify power-limited fire alarm cable categories. Use Article 760, particularly §760.179(D)–(F), for the listing references:

• FPL identifies the general-purpose category.
• FPLR, the riser category, is covered on its own page for where it is required and what it substitutes for.
• FPLP, the plenum category, is covered on its own page for where it is required and what it substitutes for.

Determine the actual use of each space along the route before choosing a category. A suspended ceiling alone does not establish an environmental-air space. Record transitions and any additional wet-location, outdoor or burial requirements in the cable schedule.

The route and wiring-method reference is §760.135; cable substitution is addressed in §760.154(A). Within these fire alarm categories, FPLP can replace FPLR or FPL, and FPLR can replace FPL. The reverse substitutions do not work: an FPL cable does not acquire a riser or plenum rating because it carries fire alarm signals. The replacement still needs to satisfy the full route conditions and the equipment's electrical limits.

For example, a fictional cable schedule reading only “red 14/2” is incomplete. Add the required listing category, route conditions, conductor construction and the selected equipment's cable requirements before evaluating a substitution. No real cable is specified by that example.

NPLF, NPLFR and NPLFP: the non-power-limited cables

FPL, FPLR and FPLP are power-limited cables. NPLF, NPLFR and NPLFP are their non-power-limited counterparts for circuits that exceed the power-limited limits, and they are covered in Part II of Article 760. The last letter reads the same way: NPLF is general-purpose, NPLFR is riser and NPLFP is plenum. Do not assume a cable works for a circuit because the letters look alike; check the substitution rules in Article 760 first. Confirm the circuit class on the drawings first, then pick the cable category for the route.

Fire alarm terms, one page each

Each of these pages takes one cable marking or circuit term, draws it, and covers how to read it and the mix-ups that trip new installers.

Twenty more terms, from smoke detector types to Class X and battery backup, are in the fire alarm terms glossary.

Read actual product specifications

These sourced products illustrate cable markings and construction. They are not equipment selections for the fictional calculation exercises:

• Southwire's 41581008 direct-burial fire alarm cable identifies an FPL category and product-specific burial suitability. FPL alone does not establish burial suitability.
• Belden's 5020UL identifies an FPLR riser cable with two solid 12 AWG copper conductors. Its riser suitability does not make it a plenum product.
• Southwire's FPLP stranded non-shielded family, SPEC13025, identifies a UL 1424 FPLP listing. The plenum category and stranded construction describe different aspects of that cable.
• Belden's 5120FL and 6100FL both have two 14 AWG conductors and an overall shield. The 5120FL uses solid conductors and FPLR construction; the 6100FL uses stranded conductors and FPLP construction. “14/2 shielded” alone does not distinguish them.

CI and two-hour protection answer another question

A plenum or riser marking addresses a cable category; it does not by itself establish continued circuit operation during fire exposure. Review NFPA 70 (2020), §760.179(G) and NFPA 72 (2022), §12.4, including §§12.4.3–12.4.4, for the relevant navigation points.

Distinguish CI cable, a listed fire-resistive cable system, and an electrical circuit protective system. “CI” concerns circuit integrity; the selected product or system listing establishes the installation conditions and time rating. A two-hour design needs evidence for the complete proposed method. A cable trade name alone is insufficient.

When reviewing a two-hour proposal, identify the listing/system reference and compare the proposed cable, supports, raceway, splices and terminations with that installation. If the design instead relies on a rated enclosure or protected route, identify the construction details and approval basis. Use §12.4 to evaluate the chosen arrangement; do not assume that two different protection methods can be mixed without review.

NFPA's Article 760 development record provides background on these distinctions. It is not a replacement for the final adopted provisions or the specific system listing.

Conductor size and shielding

Read a size such as 14/2 as two 14 AWG insulated circuit conductors; the construction schedule supplies the remaining details. The notation alone does not identify shielding, strand construction or the fire-performance category. Identify any drain wire separately. Solid means a single wire per conductor; stranded means several smaller wires form each conductor. The shield and drain wire are not spare circuit conductors.

The Notifier SLC Wiring Manual, §2.1, differentiates recommended wire types by loop-controller model. Some listed controllers use twisted unshielded pair; others use twisted shielded pair. Its §§3.2–3.5 address shield termination. Follow the exact controller instructions rather than assuming that shielding is always an improvement.

Fire alarm wire color code: use the project legend

Separate jacket color from conductor insulation color. Belden's 5120FL specification identifies black and red conductor insulation; its ordering list includes both a red-jacket option, 5120FL 0021000, and a blue-jacket option, 5120FL D151000. Those are product choices, not a universal rule assigning circuit function from jacket color.

The project legend, cable schedule, terminal markings and equipment instructions establish identification and polarity. Carry those identifiers through splices and records. Resolve a mismatch between installed colors and drawings before connecting the circuit. Color alone does not identify an SLC, NAC, polarity or permitted wiring method.

On a NAC, use the wire-size calculator to explore conductor choices and include outgoing and return conductor resistance in the voltage-drop calculation. On an SLC, also check the controller's resistance, capacitance, total-length and topology limits. A NAC voltage result cannot establish reliable SLC communication.

Use the NAC vs SLC guide for circuit roles and SLC troubleshooting guide for fault isolation. Tie the cable schedule to the riser and calculations in the submittal package. Return to Alarm Ladder or take the free Level II check.

FAQ

What is the difference between FPL, FPLR and FPLP?

The fire test and the space each is rated for. FPL is general-purpose cable, FPLR passes a riser test for vertical runs between floors, and FPLP passes a plenum flame-and-smoke test for air-handling spaces.

Can FPLR be used in a plenum?

Not on its riser rating. A riser rating does not make a cable plenum-rated, so check §760.135 in the edition your AHJ enforces for what an air-handling space allows before you pull cable.

Can FPLP be used anywhere FPL or FPLR is allowed?

As a cable category, yes: FPLP can replace FPLR or FPL. It still has to meet the route's other conditions and the equipment maker's electrical limits.

Is FPL cable rated for outdoor or underground runs?

Not by the FPL marking alone. Wet-location or burial use needs a product listed for it, like the direct-burial example above.

Is plenum fire alarm cable the same as 2-hour cable?

No. A plenum or riser rating describes how the cable resists spreading flame and smoke. Keeping a circuit working during a fire is a separate rating, met with CI cable, a listed fire-resistive cable system or a rated enclosure; NFPA 72 §12.4 is the place to start.

What color should fire alarm cable be?

No universal rule assigns circuit function by jacket color. Belden sells the same 5120FL cable with a red or a blue jacket, so follow the project legend and cable schedule.

Sources

Show the list

• UL 1424, Cables for Power-Limited Fire-Alarm Circuits, UL Standards & Engagement; scope, cable types and the fire test named for each, summarized in our own words. Checked 26 Oct 2026.
• Direct-burial fire alarm cable, 41581008, Southwire. Retrieved 17 Oct 2026; FPL designation and burial suitability.
• 5020UL, Belden. Retrieved 17 Oct 2026; solid 12 AWG construction and FPLR category.
• FPLP stranded non-shielded cable, SPEC13025, Southwire. Retrieved 17 Oct 2026; plenum category and UL 1424 listing.
• 5120FL, Belden. Retrieved 17 Oct 2026; 14/2 solid shielded FPLR construction, conductor colors and jacket-color ordering options.
• 6100FL, Belden. Retrieved 17 Oct 2026; 14/2 stranded shielded FPLP construction.
• NFPA 70 (2020), NFPA, §§760.135, 760.154(A), 760.179(D)–(G), referenced by number only. Access route retrieved 17 Oct 2026; final section text was not accessible in the public reader.
• NFPA 70 Article 760 development record, NFPA, public inputs 2180 and 299, using the 2020 edition as the revision baseline. Retrieved 17 Oct 2026; CI terminology and section-navigation background, not an adopted replacement edition.
• NFPA 70 technical-session agenda, NFPA, Article 760 material. Retrieved 17 Oct 2026; fire alarm cable substitution background; directional substitutions stated in our own words, with no tables or figures reproduced.
• NFPA 72 (2022), NFPA, §12.4, referenced by number only. Access route retrieved 17 Oct 2026.
• SLC Wiring Manual, 51253 Rev U9, Notifier, §§2–3. Retrieved 17 Oct 2026; cable electrical characteristics and shielding.
• Level II Selected General References, NICET. Retrieved 17 Oct 2026; study editions only.