Most wire and cable used in electrical installations in the United States includes a print legend — a line of text printed, embossed, or otherwise marked on the cable's outer surface that identifies what the cable is, who made it, and what it's rated for. Cable marking requirements are defined by product safety standards such as UL® and referenced by the NEC® to verify the cable type and ratings during installation and inspection. Some exceptions exist — very small gauge hookup wire, certain appliance wiring material (AWM), and some specialty or military-spec cable may carry minimal markings or rely on spool labeling and documentation instead of jacket printing.
The challenge is that print legends are not standardized in a single universal format. Different manufacturers arrange the information in different sequences, use different abbreviations, and apply the markings using different methods. This guide explains what each element of a print legend means, how to decode the most common formats, and how marking methods vary across cable types.
What Information Does a Cable Print Legend Contain?
While the exact sequence varies by manufacturer and cable type, most print legends contain the same core elements. Here's what to look for and what each element tells you.
| Element | What It Tells You | Example |
|---|---|---|
| Manufacturer name or trademark | Who made the cable | SOUTHWIRE, CERRO, GENERAL CABLE |
| UL listing mark | The cable has been tested and listed by Underwriters Laboratories for the stated application | (UL), UL, or the UL logo followed by a file number like E12345 |
| Cable type designation | The NEC® wire type and rated environment | THHN/THWN-2, NM-B, XHHW-2, MC, USE-2, SER |
| Conductor size | Wire gauge or cross-section | 12 AWG, 4/0 AWG, 250 kcmil, 2/C #14 |
| Conductor count (multi-conductor cables) | Number of insulated conductors, sometimes with ground noted separately | 3/C, 2/C + GND, 12/3 W/G |
| Voltage rating | Maximum rated voltage | 600V, 300V, 5 kV, 15 kV |
| Temperature rating | Maximum operating temperature for the insulation | 90°C, 75°C, 105°C, 150°C |
| Conductor material | Copper or aluminum | CU, COPPER, AL, ALUMINUM |
| Ratings and approvals | Fire ratings, environmental ratings, and additional listings | CMP, CMR, FPLP, SUN RES, DIR BUR, OIL RES, (FT4), c(UL) |
| Footage or meter markings | Sequential length markers showing how much cable has been paid out | 1000 FT, 0500 FT, or descending numbers |
| Date or batch code | Manufacturing date or lot number for traceability | 2025, 03-2025, LOT 4417A |
| Standards compliance | Industry standards the cable meets beyond UL | CSA, IEEE 1202, NFPA 262, ICEA S-95-658, ASTM B3 |
How to Read a Print Legend: Real-World Examples
The best way to understand print legends is to decode actual examples. The format, abbreviation style, and information order differ between manufacturers — there is no single universal standard for how the elements are arranged. Here are typical print legends you'll encounter on common cable types.
Example 1: THHN/THWN-2 Building Wire
SOUTHWIRE® (UL) E12345 12 AWG THHN/THWN-2 CU 600V 90°C SUN RES GAS/OIL RES — 0750 FT
- SOUTHWIRE® — Manufacturer
- (UL) E12345 — UL Listed, file number E12345
- 12 AWG — Conductor size (12 gauge)
- THHN/THWN-2 — Dual-rated wire type (90°C dry and wet)
- CU — Copper conductor
- 600V — Voltage rating
- 90°C — Temperature rating
- SUN RES — Sunlight resistant (suitable for outdoor conduit)
- GAS/OIL RES — Gasoline and oil resistant
- 0750 FT — Footage marker (750 feet remaining on the reel, counting down)
Example 2: NM-B (Romex) Residential Cable
ROMEX® SIMpull® 14/2 WITH GROUND TYPE NM-B (UL) 600V COPPER E34567 — 0225 FT
- ROMEX® SIMpull® — Brand name and product line
- 14/2 — 14 AWG, 2 insulated conductors
- WITH GROUND — Includes an equipment grounding conductor
- TYPE NM-B — Non-metallic sheathed cable, 90°C rated
- (UL) 600V — UL listed, 600V rated
- COPPER — Conductor material
- E34567 — UL file number
- 0225 FT — Footage marker
Example 3: Plenum-Rated Category Cable
GENERAL CABLE® GenSPEED® 6000 4PR 23AWG CAT6 CMP (UL) c(UL) CMG ETL VERIFIED E56789 ANSI/TIA-568-C.2 — 0312M
- GENERAL CABLE® GenSPEED® 6000 — Manufacturer and product line
- 4PR 23AWG — 4 pairs, 23 gauge conductors
- CAT6 — Category 6 performance rating
- CMP — Communications Plenum rated (NEC® Article 800)
- (UL) c(UL) — UL Listed for U.S. and Canada
- CMG — Canadian general-purpose communications rating
- ETL VERIFIED — Third-party performance verification
- ANSI/TIA-568-C.2 — Standards compliance reference
- 0312M — Footage marker in meters
Example 4: Fire Alarm Cable
CERROWIRE 14/2 SOLID FPLR (UL) 300V CU RED — 1000 FT P/N 123-4567
- CERROWIRE — Manufacturer
- 14/2 SOLID — 14 AWG, 2 conductors, solid copper
- FPLR — Fire Power Limited, Riser rated (NEC® Article 760)
- (UL) 300V — UL listed, 300V rated
- CU — Copper
- RED — Jacket color
- 1000 FT — Footage marker
- P/N 123-4567 — Manufacturer part number
Example 5: Tray Cable (VNTC)
MANUFACTURER 10/3 W/G VNTC TYPE TC-ER THHN/THWN-2 600V 90°C (UL) SUN RES DIR BUR E78901 — 0480 FT
- 10/3 W/G — 10 AWG, 3 conductors with ground
- VNTC — Vinyl-Nylon Tray Cable construction
- TYPE TC-ER — Tray Cable, Exposed Run (permitted outside cable tray per NEC® 336.10)
- THHN/THWN-2 — Individual conductor rating within the assembly
- 600V 90°C — Voltage and temperature rating
- SUN RES DIR BUR — Sunlight resistant and direct burial rated
How Are Print Legends Applied? Marking Methods Explained
The physical method used to mark a cable varies depending on the cable's construction, jacket material, and intended environment. Not all cables are marked the same way, and understanding the marking method can help you locate and read the legend on unfamiliar cable types.
Surface Inkjet Printing
The most common method for general-purpose cable. A high-speed inkjet printer sprays ink directly onto the outer jacket surface as the cable exits the extrusion line. The ink is typically white or yellow on dark jackets, and black or dark blue on light jackets for maximum contrast. This is how most building wire (THHN/THWN-2), NM-B, data cable, fire alarm cable, and low-voltage cable is marked. The ink sits on the surface and can wear off over time if the cable is pulled through rough conduit or handled extensively, though modern UV-cured inks are significantly more durable than older formulations.
Print Wheel (Hot Stamp / Indent Printing)
A heated print wheel or die presses the legend into the jacket material, creating raised or indented characters. This method is common on power cords (SPT, SJT, SJOOW types), appliance wire, and some portable cordage where the marking needs to survive repeated flexing, abrasion, and contact with oils or chemicals that would dissolve surface ink. The characters are embossed or debossed directly into the thermoplastic jacket during or immediately after extrusion while the material is still warm. Because the marking is physically part of the jacket, it cannot wear off — though it can be harder to read on dark or heavily textured cables. Look for it by running your finger along the jacket and feeling for the indented or raised text.
Marker Tape (Under-Jacket Tape)
Some cables use a printed marker tape applied beneath the outer jacket rather than printing on the jacket surface. The tape is typically a thin, printed film or ribbon that wraps longitudinally or helically under the jacket. This method is common on fluoropolymer-insulated cables (FEP, PFA, ETFE, PVDF) and other specialty cables with translucent or semi-translucent jackets — the print legend on the tape is visible through the jacket material. It's also used on some medium-voltage cables and cables where the jacket material doesn't accept ink well. When you see markings that appear to be "inside" the jacket rather than on the surface, you're looking at marker tape.
Laser Marking
A laser etches or discolors the jacket surface to create the print legend. Laser marking produces high-contrast, permanent text that won't smear, fade, or wash off. It's used on specialty and high-performance cables where permanence and legibility in harsh environments are critical — including some military-spec cable, aerospace wire, and high-temperature industrial cable. The laser can also mark through clear or colored jackets with precision that inkjet printing cannot match.
Extruded Ribs or Ridges
Some cables, particularly certain utility and industrial types, use extruded ribs or ridges on the jacket surface as an identification method. Rather than printed text, the number and pattern of ribs identify the cable type or phase. This is more common on medium-voltage utility cables and is typically used in conjunction with, not instead of, a printed legend.
Understanding Footage Markers
Most cable includes sequential footage (or meter) markings as part of the print legend. These markers tell you how much cable is on the reel or in the box, which is critical for estimating remaining stock, verifying put-up lengths, and measuring run lengths during installation.
How Footage Markers Work
Footage markers are typically printed at regular intervals — every 1 foot, every 2 feet, or every 5 feet depending on the cable type and manufacturer. On most building wire and low-voltage cable, markers appear every 2 feet. The numbers usually count down from the total put-up length (e.g., 1000, 0998, 0996...) so the installer can see how much cable remains without doing math.
However, not all manufacturers use the same footage marking conventions:
- Descending footage — The most common format. Numbers count down from the total reel length. When you see "0250 FT" on the jacket, there are approximately 250 feet left on the reel. This is standard on most building wire and NM-B cable.
- Ascending footage — Some manufacturers count up from zero. The number tells you how many feet have been produced from the start of the reel, not how many remain. You'll need to know the total put-up length and subtract.
- No sequential footage markers — Some cable types, particularly specialty, imported, or custom-manufactured cable, may not include sequential footage markings at all. The print legend repeats at regular intervals but without a changing number. In these cases, you'll need to measure cable length manually or rely on the reel tag for the total put-up.
- Meter markings — Cable sold internationally or manufactured to metric standards may use meters instead of feet. Look for "M" after the number (e.g., "0312M").
Footage Accuracy
Footage markers are applied during manufacturing and are generally accurate to within ±1% on quality cable. However, they should be treated as estimates, not precision measurements. Factors that can affect accuracy include printer calibration drift during long production runs, cable stretch during spooling, and the fact that the marker is applied at the time of manufacture before the cable is wound onto a reel under tension. For critical length measurements, always use a cable measurer or pull the cable through a calibrated measuring device.
UL Listing Marks: What They Mean
The UL (Underwriters Laboratories) mark on a cable print legend is one of the most important elements for code compliance. It tells you the cable has been independently tested and certified to meet specific safety standards.
Common UL Marks on Cable
- (UL) or the UL logo — UL Listed for the United States. The cable meets the applicable UL standard (e.g., UL 83 for building wire, UL 444 for communications cable, UL 1277 for tray cable).
- c(UL) or (cUL) — UL Listed for Canada (meets CSA standards evaluated by UL).
- UL file number (e.g., E12345) — The manufacturer's UL file number. This can be looked up on UL's Product iQ database (iq.ulprospector.com) to verify the listing is valid and see exactly what the cable is listed for.
- ETL — Intertek's ETL mark is an alternative to UL listing. Both are NRTLs (Nationally Recognized Testing Laboratories) accepted by OSHA, and ETL-listed cable is accepted by inspectors the same way UL-listed cable is.
- CSA — Canadian Standards Association mark. Required for cable sold in Canada.
Cable without a recognized NRTL listing mark (UL, ETL, or equivalent) will fail electrical inspection in virtually all U.S. jurisdictions. Always verify the listing mark is present and legible before installing cable on a permitted project.
Fire and Environmental Ratings on Print Legends
Beyond the basic wire type designation, print legends often include additional ratings that indicate fire performance, environmental suitability, or special approvals. Here are the most common ones you'll encounter.
| Marking | Meaning |
|---|---|
| CMP | Communications Plenum — rated for air-handling spaces (NEC® Article 800) |
| CMR | Communications Riser — rated for vertical runs between floors |
| CM / CMG | Communications General Purpose (CMG is the Canadian equivalent) |
| FPLP | Fire Power Limited Plenum — fire alarm cable for plenum spaces |
| FPLR | Fire Power Limited Riser — fire alarm cable for riser applications |
| FPL | Fire Power Limited — general-purpose fire alarm cable |
| CL2P / CL3P | Class 2 or Class 3 Plenum — power-limited cable for plenum spaces |
| CL2R / CL3R | Class 2 or Class 3 Riser |
| SUN RES or SUNLIGHT RESISTANT | UV-stabilized jacket suitable for outdoor exposure |
| DIR BUR or DIRECT BURIAL | Rated for underground installation without conduit |
| OIL RES | Oil resistant jacket (per UL 1277 or applicable standard) |
| GAS/OIL RES | Gasoline and oil resistant (common on THHN with nylon jacket) |
| W or WET | Rated for wet locations |
| TC-ER | Tray Cable — Exposed Run (allows exposed runs between cable tray and equipment per NEC® 336.10) |
| (FT4) | Canadian flame test rating (vertical tray flame test per CSA C22.2 No. 0.3) |
| LSZH or LS0H | Low Smoke Zero Halogen — produces low smoke and does not release halogenated acids when burned. Common on transit, marine, and enclosed-space applications |
| RoHS | Restriction of Hazardous Substances — complies with EU directive limiting lead, mercury, cadmium, hexavalent chromium, and certain flame retardants in cable materials. Common on electronics and export cable. Not required by the NEC® for U.S. installations. RoHS compliance may appear in the print legend, on the reel label, or only in the product spec sheet |
For a detailed explanation of plenum and riser ratings, see our Plenum vs. Riser Cable guide.
Why Print Legends Matter for Inspections and Compliance
Electrical inspectors rely on print legends to verify that the installed cable meets the requirements of the electrical permit, the NEC®, and any local code amendments. During a rough-in inspection, the inspector will physically look at the cable jacket to confirm the wire type, voltage rating, listing mark, and fire rating match what the plans and specifications call for.
If the print legend is illegible, missing, or doesn't match the required specification, the inspector can and will fail the inspection. Common issues include:
- Worn or rubbed-off ink — Aggressive pulling through conduit can wear away surface-printed legends. Use pulling lubricant and avoid dragging cable across rough surfaces.
- Wrong cable type — Installing CMR (riser) cable in a plenum space, or THHN-only wire in a wet location. The print legend is the proof.
- No UL listing — Unlisted cable or cable with a listing mark from a lab not recognized by the AHJ.
- Counterfeit or mislabeled cable — Unfortunately, counterfeit cable with fake UL marks does exist in the market. If something looks wrong — misspellings, unusual formatting, unfamiliar manufacturer name — verify the UL file number at UL Product iQ before installing.
On existing installations, the print legend is also how you identify what's already in the wall or conduit when adding to or troubleshooting a system. This is why legibility and permanence of the marking method matters long after the initial installation.
Why Print Legends Look Different Across Manufacturers
There is no single mandatory format for how print legend elements must be sequenced. UL and the NEC® require that specific information be present on the cable marking, but they do not dictate the exact order, spacing, or abbreviation style. As a result, you'll see significant variation between manufacturers.
Common differences include:
- Element order — Some manufacturers lead with the brand name, others with the UL mark or wire type. There is no "correct" sequence.
- Abbreviations — One manufacturer may print "SUNLIGHT RESISTANT" while another prints "SUN RES" or "SR." Both are acceptable.
- Footage marker format — Leading zeros, trailing "FT" or "M" labels, ascending vs. descending count, or no sequential markers at all.
- Repeat interval — The print legend typically repeats every 2 to 5 feet on small cable and every 5 to 10 feet on larger cable, but the interval varies by manufacturer and cable type.
- Additional marketing text — Some manufacturers include brand names, product line names, or patent numbers alongside the required markings.
- Color and font — Ink color, character size, and font vary. White ink on dark jackets is most common, but some cables use yellow, blue, or even multi-color printing.
The important thing is that the required information is present and legible — not that it matches a specific template. When in doubt about what a marking means, look up the UL file number or contact the manufacturer directly.
Frequently Asked Questions
What does the number on my cable mean?
If you see a changing number along the length of the cable (like 0500, 0498, 0496...), that's the footage marker — it tells you how many feet are left on the reel (if counting down) or how many feet have been produced (if counting up). If the number doesn't change, it's likely the conductor size (e.g., "12" for 12 AWG) or voltage rating (e.g., "600" for 600V). Look at the surrounding text for context.
Why can't I find the print legend on my cable?
The marking method depends on the cable type. If you don't see surface printing, check for embossed or indented characters by running your finger along the jacket — this is common on power cords and portable cordage. On fluoropolymer cables (FEP, PFA, ETFE), look through the translucent jacket for marker tape underneath. On some flat cables and cords, the legend may be on only one side.
The print has worn off my cable. Is it still code-compliant?
The cable itself hasn't changed — it's still the same product with the same ratings. However, an inspector may require you to verify the cable type through other means if the legend is illegible. Some options include: checking the reel tag (which should match the cable), looking up the manufacturer and part number, or pulling a section from deeper on the reel where the print is intact. For new installations, use pulling lubricant and handle cable carefully to preserve the legend.
What does "(UL)" vs "UL" vs the UL logo mean on cable?
All three indicate UL listing. The parenthetical (UL) is the most common format on cable print legends simply because the UL logo is difficult to reproduce with high-speed inkjet printing. The key is the presence of a UL file number (the "E" number) which you can verify online. The format of the mark itself is less important than its presence and verifiability.
How do I verify if a UL listing is real?
Go to UL's Product iQ database at iq.ulprospector.com and search for the file number from the cable's print legend. The database will show the manufacturer, the product categories covered under that listing, and the specific standards the product is listed to. If the file number doesn't exist or doesn't match the cable type, the listing may be counterfeit.
Why does my cable say both THHN and THWN-2?
Because the cable is dual-rated — it meets the requirements of both designations simultaneously. Most modern building wire is manufactured this way, giving you 90°C performance in both dry and wet locations. See our THHN vs THWN Building Wire guide for a detailed explanation of what each designation means.
What does "c(UL)" mean on cable?
The "c" prefix indicates Canadian certification. c(UL) means UL has evaluated the cable to Canadian standards (CSA). Cable marked with both (UL) and c(UL) is listed for use in both the United States and Canada. This is common on cable sold throughout North America.
Do all cables have footage markers?
No. While most U.S.-manufactured building wire, NM-B, and structured cabling includes sequential footage markers, some cable types do not. Specialty cables, imported cables, short custom runs, and some industrial cable may have a repeating print legend without any changing footage number. In these cases, check the reel tag for the total put-up length and measure cable during installation if precise lengths are needed.
Related Resources
- THHN vs THWN Building Wire: Ratings & Applications
- AWG Wire Gauge Guide: Sizes, Ampacity & Selection
- Plenum vs. Riser Cable: CMP, CMR, CL2P & CL3P Ratings Explained
- How to Choose the Right Cable for Your Project
- Fire Alarm Cable: Types, Ratings & NEC Requirements
Need Help Identifying a Cable?
If you've got a cable and can't figure out what it is from the print legend, our sales team can help. Send us a photo of the marking and we'll identify the cable type, ratings, and whether we carry it or an equivalent. We can also help you specify the correct replacement cable for your application.
Disclaimer: This guide is provided for informational purposes only and is not installation advice. It does not constitute professional electrical, engineering, or code-compliance advice. Installing wire & cable can be dangerous and pose a risk of possible electric shock or other hazards. Building codes, NEC editions, and local amendments change periodically. Always consult a licensed electrician and your local authority having jurisdiction (AHJ) before specifying or installing cable.
The information on this page is provided for general reference only and may contain errors or omissions. Print legend examples shown above are representative and may not match the exact format used by any specific manufacturer. NEC® is a registered trademark of the National Fire Protection Association (NFPA®). UL® is a registered trademark of Underwriters Laboratories. Romex® is a registered trademark of Southwire Company, LLC. All other trademarks, product names, and brand names referenced on this page are the property of their respective owners. Ramcorp Wire & Cable is not affiliated with or endorsed by these organizations unless explicitly stated.