CL2 vs CL3 HDMI Cable: What the Rating Permits
Quick answer / TL;DR: Short answer: CL2 and CL3 are Class 2 and Class 3 cable ratings under NEC Article 725. An HDMI cable carries an extremely low-power signal and is normally installed as a Class 2 circuit, so CL2 is the applicable rating for in-wall use. CL3 permits higher voltage and power and is not required for HDMI, though a CL3 cable is acceptable where CL2 is required. Neither rating describes signal quality; for plenum air spaces the relevant rating is CMP, which is a different requirement.
The jacket ladder: each rating unlocks a route – general, riser, plenum, exterior.CL2 and CL3 appear on HDMI cable listings as if they were quality tiers. They are not. They are jacket ratings from the National Electrical Code's Article 725, describing what voltage and power class the cable is permitted to carry in a given location.
For an HDMI cable the practical question is simpler than the label suggests: the cable carries a low-voltage signal, so it needs a class rating appropriate for in-wall installation, and the highest available rating is not automatically necessary.
What CL2 and CL3 Actually Classify
Article 725 divides low-voltage circuits into Class 1, Class 2 and Class 3 based on the power available and the voltage. The cable rating follows the circuit class, so a CL2 cable is listed for Class 2 circuits and a CL3 cable for Class 3.
| Rating | Circuit class | Typical use | Applies to HDMI? |
|---|
| CL2 | Class 2, limited power | low-voltage signal and control cable | yes, normal case |
| CL3 | Class 3, higher power than Class 2 | audio, control with more power | acceptable but not required |
| CMR | riser location | vertical shafts between floors | separate requirement |
| CMP | plenum air space | return-air ceilings | separate requirement |
The two axes are independent. A cable can be CL2 and CMR, or CL3 and CMP, and the markings are usually printed together. Reading only the CL number tells you half of what the installation requires.
Why HDMI Is Normally CL2
An HDMI cable carries a signal at a few volts and very low current, plus a small amount of power for the source electronics. That places it comfortably inside Class 2 limits. A CL3 rating permits higher power, which an HDMI cable does not need.
So the practical answer to the comparison is that CL2 is sufficient and CL3 is harmless. A listing that charges more for CL3 on an HDMI cable is not selling a better cable; it is selling a rating the application does not use.
The Rating That Often Matters More
Location decides the required jacket, and location requirements are stricter than circuit class in many buildings. A cable in a return-air ceiling must be plenum rated regardless of its CL number.
- In a wall between studs: aCL2 or CL3 rating is typically required for the cable to be installed without conduit
- In a riser between floors: CMR, the riser rating
- In a return-air ceiling: CMP, the plenum rating
- In a raceway or conduit: the raceway may satisfy the requirement, but the cable still needs a listing
- Under carpet or in a floor: specific listings apply, and standard CL2 may not be acceptable
The reason is fire behaviour rather than signal. Plenum cable uses low-smoke, low-toxicity materials so a fire in a return-air space does not distribute combustion products through the building.
What This Means When Buying
| Claim on the listing | What it tells you | What to ask |
|---|
| CL2 rated | listed for Class 2 circuits | jacket print showing CL2 plus any location rating |
| CL3 rated | listed for Class 3 | whether the application actually needs it |
| In-wall rated | often means CL2 or CL3 | which rating, printed where |
| Plenum | CMP jacket | test standard and listing number |
| No rating stated | unverified | jacket print, and a listing reference |
The jacket print is the evidence. A cable described as in-wall rated without a printed CL2, CL3, CMR or CMP marking should be treated as unverified, because the rating is a listing rather than a design intention.
Real-World Applications
Television mounted on a wall with cables in the cavity
The run inside the wall needs a CL2 or CL3 rated cable, sized for the format. Confirm the rating is printed on the jacket before the cable disappears into the cavity, since it cannot be checked afterwards without removing the display.
Office with a return-air ceiling
The ceiling void is a plenum, so CMP is required whatever the circuit class. This is the single most common code failure in commercial AV work: a CL2 cable installed in a plenum ceiling because the installer read only the CL number.
Riser between floors in a house
A vertical run between floors is a riser, which calls for CMR. Many CL2 cables are also CMR rated, and the jacket print will show both markings. Check before ordering, because not all are.
Standards and Verification
Jacket ratings come from the electrical code and from the listing standards, which is what makes the marking meaningful.
- NFPA 70, National Electrical Code, Article 725: Class 1, 2 and 3 circuit definitions and cable requirements
- NFPA 70, Articles 800 and 820: communications and coaxial cable requirements, including riser and plenum rules
- UL 444: communications cable safety standard referenced by the listings
- UL 1685 and NFPA 262: flame and smoke test methods behind CMR and CMP ratings
- IEC 60332 series: the international flame propagation test methods
Verification is a physical read before installation. Check that the jacket print shows the circuit class and the location rating, and record a photograph of the print for the handover file. After installation the print is inaccessible, so the record is the only evidence that the correct cable was used.
Related reading: Plenum cable: CMP ratings and where they apply — blogs/news/plenum-cable
Related reading: Cat6 plenum vs riser: choosing the jacket — blogs/news/cat6-plenum-vs-riser
Related reading: HDMI cable guide: versions, bandwidth and limits — blogs/news/hdmi-cable
Frequently Asked Questions
Do I need a CL3 HDMI cable?
No. An HDMI cable carries a low-power signal and is normally a Class 2 circuit, so CL2 is the applicable rating. CL3 is acceptable but not required, and it does not improve signal quality.
What is the difference between CL2 and CL3?
They are circuit class ratings under NEC Article 725. CL2 covers Class 2 circuits with limited power, CL3 covers Class 3 with higher power. Both are low-voltage cable ratings, not performance grades.
What rating do I need for a ceiling?
If the ceiling is a return-air plenum, you need CMP. A CL2 rating alone does not satisfy a plenum requirement, which is a separate and stricter condition.
Is in-wall rated the same as CL2?
Often the phrase means CL2 or CL3, but it is not a defined rating. Ask for the actual marking printed on the jacket, and confirm it matches the installation location.
Does CL2 affect picture quality?
No. The rating describes fire and circuit behaviour, not electrical performance. Picture quality depends on the cable's bandwidth class, such as Premium High Speed or Ultra High Speed.
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