HDMI cables — length, type and in-wall rating

Wall-mounting changes your cables in two ways: they get longer, and some of them disappear into the wall where you can't easily replace them. Both make the choice matter more than it does on a TV stand.

The certification labels

Ignore words like "premium gold" on the box and look for the official names:

• High Speed: 1080p and basic 4K at 30 Hz. Old.
• Premium High Speed (18 Gbps): 4K at 60 Hz with HDR. Fine for streaming boxes, cable boxes and most uses.
• Ultra High Speed (48 Gbps): 4K at 120 Hz, 8K, variable refresh rate. What current game consoles and high-end sources want.

Certified cables carry a scannable label on the packaging. If the cable is going inside a wall, buy Ultra High Speed — it costs little more and you won't be re-pulling it for the next device.

How long can it be?

Signal weakens with length, and higher data rates weaken faster.

• Up to about 10 feet: any certified passive cable works.
• 10 to 15 feet: passive Ultra High Speed cables exist but quality varies; buy certified.
• 15 to 25 feet at 4K60: good passive Premium High Speed cables usually work.
• Beyond that, or long runs at 48 Gbps: use an active or fibre-optic (AOC) HDMI cable.

Active and fibre cables

• Active cables have a small chip that boosts the signal. They're directional: one end is marked "Source" and the other "TV/Display".
• Active optical cables carry the signal as light and run 50 feet or more at full speed. Thin and flexible, also directional, and they don't like sharp bends.

Label the ends before pulling a directional cable through a wall. Installed backwards, it doesn't work.

In-wall ratings

Cables inside walls should be rated for it. Look for CL2 or CL3 (or CMR/CMP) printed on the jacket. This is about fire safety — how the jacket behaves in a fire — not picture quality. Many "in-wall" HDMI cables are CL3.

Leave yourself a way out

• Pull one more cable than you need (or a pull string) while the wall is open.
• Better: a conduit between the TV and the equipment, so cables can be changed in minutes.
• Don't bend cables sharply at the wall plate; leave a gentle loop.

Connectors and tight spaces

A straight HDMI plug needs about 2 inches behind the TV. With slim mounts, use right-angle adapters or ports that face sideways. See flush and ultra-slim mounts.

eARC and soundbars

For a soundbar using eARC, use at least a Premium High Speed cable between the TV's eARC port and the soundbar; older cables can cause dropouts. More in connecting a soundbar with ARC and eARC.

Do expensive cables look better?

No. HDMI is digital: a cable either delivers the data or it produces sparkles, dropouts or a blank screen. A certified cable of the right type and length is as good as it gets.

Symptoms of a marginal cable

Flashing black screens, "no signal" at 4K120 but fine at 4K60, sparkling pixels, or HDR that won't switch on. Try a shorter or certified cable before blaming the TV.

We can supply a certified 4K HDMI cable with your install for $15.