Fire alarm cable is ordered as though it were one product with one rating. It is three families with three sets of letters, and the code keeps them apart on purpose. A specification that says "fire alarm cable, plenum" has narrowed almost nothing, because whether that means FPLP, NPLFP or OFNP depends on a decision nobody has made yet.
The decision is not about the cable. It is about the circuit.
One name, three families
The article that covers fire alarm systems settles a power question before it settles anything about fire. A fire alarm circuit is 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 system, and the code then states the split directly: fire alarm circuits are classified as either non-power-limited or power-limited.
Those two classes are not two grades of the same cable. They are two divisions of the same article with separate power source rules, separate conductor rules and separate listing families. A non-power-limited fire alarm circuit, abbreviated NPLFA, is one powered by a source complying with the clauses for non-power-limited supply. A power-limited fire alarm circuit, PLFA, is one powered by a source complying with the power-limited clause.
Optical fiber fire alarm circuits are a third case again, because the article routes them out to the fiber article rather than keeping them in.
Circuit class | Listing family | Tiers, from plenum down to general purpose |
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Power-limited fire alarm (PLFA) | FPL | FPLP / FPLR / FPL |
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Non-power-limited fire alarm (NPLFA) | NPLF | NPLFP / NPLFR / NPLF |
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Optical fiber fire alarm | OFN | OFNP / OFNR / OFN |
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Three families, each with the same three-tier structure, each tier naming the space it is qualified for. The structure repeats because the question repeats: how much smoke and flame the cable contributes where it sits.
Three families with three tiers each
The split comes first: power-limited and non-power-limited
The reason the split matters more than the space is that it changes which clauses apply. The article has a part for non-power-limited circuits and a part for power-limited circuits, and the requirement clause sends each class to its own.
The two classes also diverge on things a purchaser would notice. In the non-power-limited family the conductors must be 18 AWG or larger, solid or stranded copper, and insulated conductors rated for 600 volts. In the power-limited family the conductor rules come from elsewhere in the article and permit smaller constructions.
The power source clauses differ in character as well. In the non-power-limited family the branch circuit supplying the fire alarm equipment must supply no other loads, and the branch-circuit overcurrent protective device must be permanently identified at the fire alarm control unit. The disconnecting means must have red identification, be accessible only to qualified personnel, and be identified as "FIRE ALARM CIRCUIT." Then a requirement that surprises people who have not read the clause: that branch circuit shall not be supplied through ground-fault circuit interrupters or arc-fault circuit interrupters.
The scope also draws a narrower boundary than most people assume. Circuits for elevator capture, door release, damper control and fan shutdown are inside the article only where they are powered by and controlled by the fire alarm system, so a damper that happens to be a fire damper is not a fire alarm circuit.
If the question is | The article that answers it |
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Which listing family applies | The fire alarm article, chosen by power limitation first |
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What the plenum or riser requirement is | The air-handling space clauses the article references |
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Whether a building control circuit belongs here | The building control circuits article, unless the alarm system powers and controls it |
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What a fiber fire alarm circuit must use | The optical fiber article |
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What applies in a classified location | The hazardous location articles |
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The power-limited family and its three tiers
For power-limited fire alarm cable the article does not leave the tiers to convention. It requires cables to comply with one of three location clauses, or with the substitution table.
Space | Tier required, and what else that clause permits | Circuit integrity variant |
|---|
Ducts, plenums and other spaces used for environmental air | FPLP, with FPLP, FPLR and FPL also permitted where installed in compliance with the air-handling clause | FPLP-CI, for a two-hour circuit integrity rated cable |
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Vertical runs penetrating more than one floor, or in a shaft | FPLR | FPLR-CI, on the same basis |
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One- and two-family dwellings | FPL, the residential allowance rather than a general one | FPL-CI |
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Other building locations, including raceways | FPL | FPL-CI, for a two-hour rating |
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Read the middle column downward and the structure is the same as the communications family: a tier named for the space, with the more demanding space naming the more demanding cable.
The non-power-limited family, which is a different family
The non-power-limited family has its own listing clause and its own tier names, and this is where a specification written from memory usually goes wrong. The tiers are NPLFP for the air-handling space, NPLFR for risers, and NPLF for general use.
The listing clause sets out what each tier must demonstrate. NPLFP must be listed as suitable for use in the air-handling space, and must also be listed as having adequate fire-resistant and low smoke-producing characteristics. The clause’s note gives one method of defining those, and the numbers matter because they come from the same test the communications family is measured against: a maximum peak optical density of 0.5 or less, an average optical density of 0.15 or less, and a maximum flame spread distance of 1.52 m (5 ft) or less.
Cable used in a wet location must be listed for use in wet locations or have a moisture-impervious metal sheath.
The substitution table only runs one way
The article does not only say which cable each location needs. It also permits substitutions, in a table, and the shape of that table is the most useful thing in the article.
Cable type | Clause it is tied to | Cable that may be used in its place |
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FPLP | Plenum | CMP |
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FPLR | Riser | CMP, FPLP, CMR |
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FPL | General purpose | CMP, FPLP, CMR, FPLR, CMG, CM |
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Read the rows downward and the hierarchy appears. A plenum-rated cable appears in the substitution list for the riser row and for the general purpose row, so it can stand in for either. A riser-rated cable appears in the general purpose row but not in the plenum row, so it cannot stand in for a plenum cable. A general purpose cable appears in no other row at all.
The direction is what matters. A cable rated for the more demanding space substitutes for one rated for a less demanding space, and never the reverse. No row lets an FPL take the place of an FPLR or an FPLP, and a substitution made in the wrong direction is not an alternative compliance path. It is the wrong cable.
One sentence in the clause is easy to skim past. Where substitute cables are installed, the wiring requirements of the article’s first two parts still apply. Substituting a cable does not import the rules of the family it came from.
Substitution runs downward only
Why a communications cable is in a fire alarm table
Look again at the substitution column. Every entry in it belongs to the communications family. No row offers another fire alarm cable type as the substitute, and none needs to, because the rows are already ordered by space. What the table is doing is telling an installer that a communications cable of the correct tier satisfies the fire alarm requirement for that space.
That is not a loophole. The communications family and the power-limited fire alarm family are both listed against the same air-handling space test, which is why the substitution is coherent: a plenum-rated communications cable has demonstrated the same fire and smoke performance as a plenum-rated power-limited fire alarm cable. The article even points the reader at the communications listing clause for the definitions of CMP, CMR, CMG and CM.
The consequence runs against intuition. On a power-limited fire alarm circuit a CMP communications cable may be installed in place of an FPLP cable. On a non-power-limited circuit nothing in this table applies, because the table lives in the power-limited part of the article. The crossing exists on one side of the split and not on the other.
The crossing exists on one side of the split
Where general purpose cable may not go, even when it fits
Three clauses narrow the general purpose tier further, and each catches a different mistake.
Riser penetrations. Where a floor penetration requires Type FPLR, the penetration shall contain only cables suitable for riser or plenum use. Installing an FPL cable through the same penetration because the penetration is already firestopped is not permitted, and the clause is written to close that argument. Where cables other than FPLR are used in a vertical run, they must be installed in metal raceways or located in a fireproof shaft with firestops at each floor.
Exposed length. In nonconcealed spaces, cables meeting the conductor requirements may be installed where the exposed length does not exceed 3 m (10 ft). Ten feet is a distance, not a judgment.
Dwellings. Type FPL is permitted in one- and two-family dwellings. The allowance is written for that occupancy, which is another way of saying the general purpose tier is not freely available everywhere a general purpose cable would physically fit.
FAQ
Is fire alarm cable the same as plenum-rated communications cable?
They are different listing families with separate clauses, but the substitution table permits a communications cable of the matching tier to stand in for a power-limited fire alarm cable. A CMP cable may be used in place of an FPLP, and a CMR in place of an FPLR or an FPL. The substitution does not run in the other direction, and it does not extend to non-power-limited fire alarm cable.
Can a plenum-rated fire alarm cable be used in a riser?
Yes. The substitution table lists FPLP among the cables permitted in place of FPLR. The reverse is not permitted: FPLR is not listed among the cables that may replace FPLP.
Which family does a given installation need?
The circuit decides first, not the space. A non-power-limited fire alarm circuit takes the NPLF family, with a minimum conductor size of 18 AWG copper and 600 volt insulated conductors, and the substitution table does not apply to it. A power-limited circuit takes the FPL family, where the substitution table applies.
Conclusion
Fire alarm cable is not one product. It is a power-limited family, a non-power-limited family and a fiber family, each with its own article clauses and its own three-tier structure, and the tier letters differ between them.
The order of the questions is fixed. First, is the circuit power-limited or not, because that selects the family and decides whether the substitution table is even in play. Second, which space is the cable in, because that selects the tier. Third, is a substitution being used, and if so is it running in the permitted direction. The cable is named at the end of that sequence, and a specification that starts with the cable is answering the third question before the first two have been asked.
Fire alarm and life safety cable
ZONG Cable builds cable assemblies and states, before an order, which construction and which marking a cable will carry and what listing basis it is built against, so the tier letters on the reel match the clause the design was drawn to. Send us the circuit class, the space and the listing basis you are working to, and we will set out the construction that satisfies them. The range sits under cable, the communications family the substitution table draws on is covered in the guide to CM, CMR and CMP, the air-handling space the plenum tier is defined against is explained in what counts as a plenum space, the test behind the plenum listing is set out in the guide to NFPA 262 and UL 444, floor penetrations are covered under firestop and cable penetration, and private-label marking and labeling programs sit under OEM support.
Sources
- NFPA 70, National Electrical Code, 2011 edition, Article 760, Fire Alarm Systems. Read directly for this article: 760.1 Scope, including the statement that the article covers the installation of wiring and equipment of fire alarm systems including all circuits controlled and powered by the fire alarm system, and Informational Note No. 1 listing fire detection and alarm notification, guard’s tour, sprinkler waterflow and sprinkler supervisory systems and the building systems safety functions circuits including elevator capture, elevator shutdown, door release, smoke doors and damper control, fire doors and damper control and fan shutdown, qualified by the condition that these circuits are covered only where powered by and controlled by the fire alarm system; 760.2 Definitions, including abandoned fire alarm cable, fire alarm circuit defined 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 system together with the statement that fire alarm circuits are classified as either non-power-limited or power-limited, fire alarm circuit integrity cable, non-power-limited fire alarm circuit, and power-limited fire alarm circuit; 760.3 Other Articles, including the statement that only those sections of Article 300 referenced in the article apply, (C) hazardous (classified) locations referring to Articles 500 through 516, (E) building control circuits referring to Article 725, and (F) optical fiber cables referring to Article 770; 760.24 Mechanical Execution of Work; 760.25 Abandoned Cables; 760.30 Fire Alarm Circuit Identification; 760.32 Fire Alarm Circuits Extending Beyond One Building; 760.35 Fire Alarm Circuit Requirements; 760.41 NPLFA Circuit Power Source Requirements, including (A) the output voltage limit of 600 volts nominal and (B) the requirement that the branch circuit supply no other loads, that the location of the branch-circuit overcurrent protective device be permanently identified at the fire alarm control unit, that the circuit disconnecting means have red identification and be accessible only to qualified personnel and be identified as FIRE ALARM CIRCUIT, that the red identification not damage the overcurrent protective devices or obscure the manufacturer’s markings, and that the branch circuit not be supplied through ground-fault circuit interrupters or arc-fault circuit interrupters; 760.154 Applications of Listed PLFA Cables, including (A) Plenum and the FPLP requirement together with the permission for Types FPLP, FPLR and FPL and for FPLP-CI to provide a 2-hour circuit integrity rated cable, (B) Riser and the FPLR requirement for vertical runs penetrating more than one floor or in a shaft together with the statement that floor penetrations requiring Type FPLR shall contain only cables suitable for riser or plenum use, the permission for FPLR-CI, the metal raceway or fireproof shaft alternative with firestops at each floor, and the permission for Type FPL in one- and two-family dwellings, (C) Other Wiring Within Buildings including the permission for Type FPL, installation in raceways, the nonconcealed space allowance where the exposed length does not exceed 3 m (10 ft) for cables specified in Chapter 3 and meeting 760.179(A) and (B), the portable fire alarm system provision, and the permission for FPL-CI, and (D) Fire Alarm Cable Substitutions; Table 760.154(D) Cable Substitutions in full, giving CMP as the permitted substitution for FPLP, CMP, FPLP and CMR for FPLR, and CMP, FPLP, CMR, FPLR, CMG and CM for FPL, with the accompanying statement that cable A shall be permitted to be used in place of cable B; and the informational note referring to 800.179 for communications cables CMP, CMR, CMG and CM. https://archive.org/details/gov.law.nfpa.nec.2011
- NFPA 70, 2011 edition, Article 760, Part IV, Listing Requirements. Read directly for this article: 760.176 Listing and Marking of NPLFA Cables, including the requirement that non-power-limited fire alarm cables installed as wiring within buildings be listed in accordance with 760.176(A) and (B) and as being resistant to the spread of fire in accordance with 760.176(C) through (F) and be marked in accordance with 760.176(G), and the requirement that cable used in a wet location be listed for use in wet locations or have a moisture-impervious metal sheath; 760.176(A) NPLFA Conductor Materials, requiring conductors of 18 AWG or larger, solid or stranded copper; 760.176(B) Insulated Conductors, requiring a rating of 600 volts and referring conductors of 14 AWG and larger to Table 310.104(A) and conductors of 18 AWG and 16 AWG to 760.49; 760.176(C) Type NPLFP, requiring the cable to be listed as suitable for use in other space used for environmental air as described in 300.22(C) and as having adequate fire-resistant and low smoke-producing characteristics, together with its informational note giving one method of defining those characteristics as a maximum peak optical density of 0.5 or less, an average optical density of 0.15 or less, and a maximum flame spread distance of 1.52 m (5 ft) or less when tested in accordance with NFPA 262-2007. https://archive.org/details/gov.law.nfpa.nec.2011
- ZONG Cable range. https://zh-zong.com/cable/
