NFPA 262 and UL 444 Explained: How to Read a Cable Listing Before You Trust It

October 5, 2026

The inspector does not read your submittal. He reads the jacket.

That is the whole argument for understanding NFPA 262 and UL 444. One is the test that decides whether a cable may sit in an air-handling space. The other is the standard behind the mark that says somebody independent actually tested it.

Two Standards, Two Different Jobs

These two documents get lumped together because they both show up on the same jacket. They answer different questions.

NFPA 262 answers: what did the cable do when it burned? It is a fire test method — a procedure, not a recipe for cable construction. It tells you whether flame travel and smoke production fall inside limits a code official will accept for a plenum.

UL 444 answers: who checked it, and against what? It is a safety standard for communications cables, and it is the standard UL names when it explains what its own certification mark means.

The difference matters when something goes wrong. A cable that fails inspection gets measured against NFPA 262. A certificate that turns out to be decorative usually claimed UL 444.

If you are still working out which rating your route actually requires, the CM, CMR and CMP jacket rating guide starts from the route rather than the part number.

What NFPA 262 Actually Measures

The full title is *Standard Method of Test for Flame Travel and Smoke of Wires and Cables for Use in Air-Handling Spaces*. Its stated purpose is to measure and record the fire and smoke characteristics of insulated, jacketed, or both, electrical wires and cables and optical fiber cables that are to be installed in ducts, plenums, and other spaces used to transport environmental air without being enclosed in raceways.

Notice what that scope leaves out. If your cable sits inside a raceway, NFPA 262 is not the test that governs it. The plenum rating exists for cable that is out in the airflow.

Inside the Steiner tunnel

The hardware has not changed much in decades. A cable sample is laid in a tray, one layer deep, inside a 25-foot tunnel with an intake duct, an exhaust duct, and a way to regulate air velocity. Two circular burners sit vertically at the intake end, just ahead of the tray. Methane feeds the flame, a forced draft of 240 feet per minute pulls air through, and the burn runs for twenty minutes before the flame is extinguished.

Measurements run the whole time. Windows spaced at one-foot intervals give flame-travel readings along the tunnel, and an optical device in the exhaust stream measures smoke density.

You will still hear this called the Steiner tunnel test, and older documents may call it UL 910. That number is retired.

The pass criteria

A cable qualifies as plenum-rated when three numbers all land inside their limits:

Measurement	Limit
Flame travel distance	Not exceeding 1.52 m (5 ft)
Peak optical density of smoke	Not exceeding 0.50
Average optical density of smoke	Not exceeding 0.15

Three independent sources state these figures identically, and the reference note in the standard repeats them. Even so, if you are writing them into a submittal, pull them from the standard text rather than from a blog. Including this one.

Cable that passes is described in code language as having adequate fire-resistant and low smoke-producing characteristics. In the market it is called CMP.

Where NFPA 262 sits in the code

NFPA 262 is referenced by NFPA 90A, which governs air-conditioning and ventilating system installations, and by NFPA 70 — the National Electrical Code. The NEC carries the same pass/fail requirements as the basis for listing plenum cables, across articles covering Class 1-3 circuits (725), fire alarm (760), optical fiber (770), communications (800), CATV (820) and network-powered broadband (830).

One caution on citing article numbers. The NEC’s communications chapters have been reorganised more than once, and the location of the communications-circuit rules has moved between editions. NFPA documents that restructuring openly. So cite the article number from the edition your authority having jurisdiction actually enforces, and check it rather than assuming it travelled.

What UL 444 Covers

UL 444 is the Standard for Safety of Communications Cables, and it is a binational U.S./Canada consensus standard. The Canadian counterpart is CSA C22.2 No. 214.

UL is direct about the relationship in its own description of its telecommunications cable testing service: the UL Certification Mark signals alignment to the safety standards outlined in UL 444. Keep that sentence in your pocket. The mark is not decorative and it is not self-issued. It points at a named standard.

UL 444 is not a fire test

This is where people get tripped up, and it costs them.

UL 444 covers a communications cable as a product — construction, materials, electrical and mechanical requirements, and the safety provisions applying to cable intended for on-premise voice, data, audio and telephone circuits. It is not the plenum flame test. A cable can be built to UL 444 and still not be plenum-rated. Plenum comes from NFPA 262, on top of that.

Two separate gates: UL 444 as a product, NFPA 262 for a specific installation environment.

The edition trap

UL’s standards catalogue lists UL 444 Edition 5 — published January 2017, last revised and ANSI-approved June 2023 — as superseded. Certificates in circulation may therefore cite editions that are no longer current. Read the edition line. If it points at a superseded edition and the revision history touched anything in scope for your project, ask what changed.

The counterfeit problem

UL has published research into the safety risks created by counterfeit, uncertified and self-certified communications cable. Cable carrying a CMP marking that never passed NFPA 262 removes the entire justification for the plenum requirement — reduced flame travel, reduced smoke — while looking identical in the box. For a buyer the lesson is unglamorous: the jacket print is a claim, and every claim needs a document behind it.

The Other Tests You Will See on a Jacket

Plenum is not the only rating, and the test numbers are not interchangeable.

Rating	Common fire test	What it covers
CMP	NFPA 262 (formerly UL 910)	Plenum and air-handling spaces
CMR	UL 1666	Vertical riser routes
CM	UL 1581 / UL 1685	General-purpose indoor routes
CMX	UL 1581	Limited use, often outdoor or residential

On the Canadian side the equivalent designations are the FT series. FT6 is the NFPA 262 Steiner tunnel test under a different label. FT4 is a vertical tray test — the same procedure as IEEE 1202, both published in UL 1685 — where passing means charred material does not extend more than 1.5 m (5 ft) above the lower edge of the burner face. FT1 is the lightest of the three, a 3,000 BTU/hour flame applied five times for 15 seconds.

The point is not memorisation. It is to notice when a datasheet maps the wrong test to the wrong rating. That mistake turns up in knock-off spec sheets more often than anyone would like.

Which of the four your route needs is a separate decision, and it turns on the space rather than the price. The route-by-route selection guide works through it step by step.

How to Verify a Listing Before You Buy

Five steps. None of them take long.

Read the jacket print on the actual reel. Not the brochure, not the website. The marking on the product is what gets inspected, so photograph it.
Ask which standard and which edition each marking cites. "CMP" on its own is not enough. You want the standard number and the edition behind it.
Ask for the listing document, not a certificate of compliance. A listing from a recognised testing organisation means the product is under ongoing follow-up. A one-page letter means somebody tested one sample once.
Confirm the marking matches the project specification. If the spec names NFPA 262 and the supplier cites a different test, that conversation belongs before the container ships, not after.
Request the report for the reel you are buying — not the report for the product family.

Any manufacturer running a real testing programme can produce all five without stalling. If the answers come back as a marketing PDF, you have your answer.

Our own certifications page lists what we hold and to which standard.

The Short Version

NFPA 262 is the test; UL 444 is the product standard behind the mark. Plenum-rated cable passed the first, a certified cable passed the second, and neither substitutes for the other.

Check the marking on the reel, the standard and edition behind it, and whether the report belongs to the cable you are actually buying. Those three checks are the ones buyers skip most often, and the ones that cause the most trouble.

If your project documents name a standard and you want confirmation that we can supply against it, send us the specification and we will tell you what we can certify and to which edition.