14m 30mm Ultra-Bright COB LED Strip (40W/m) – Mains Dimming with Independent 5m Sections

Project overview

This is a typical 14 metre indoor run of Hi-Line’s 30 mm ultra-bright COB LED strip at 40 W per metre, 24 V, 3000 K. The strip is sold as 5 m rolls. For 14 m you order three 5 m rolls and cut the last roll to 4 m on a marked cut point (1 m leftover as spare).

The three lengths sit in one profile so they look like a single continuous line. Electrically they stay three independent sections. There is no 24 V join between the pieces.

A single 300 W driver cannot run this load. Rated power is 14 m × 40 W/m = 560 W. Each 5 m section is about 200 W; the 4 m piece is about 160 W. The correct rule for this strip is one 300 W hybrid driver per 5 m maximum.

Why you must not treat 14 m as one electrical run

This 30 mm COB is a high-current tape. If you feed a long length from one end only, voltage falls along the copper. The far end goes dimmer and the colour shifts (usually warmer / slightly pink). Feeding 13–14 m from one 300 W supply also overloads that driver.

The reliable method is to treat each 5 m (or the final 4 m) as its own circuit:

• Power both ends of that section from its own driver.
• Do not connect the 24 V of one section to the next.
• Keep the three sections on the same dimming signal so they still dim as one line.

Recommended parts (same package for a 14 m install)

• 3 × 30 mm ultra-bright COB 3000 K 24 V 5 m — HL-COB-24V-3K-40W-IP00 (cut the third roll to 4 m)
• 3 × 300 W hybrid mains-dimmable drivers — HL-10VT300W-24V-IP67-GF-5Y (one driver per section)
• 3 × mains dimming boosters — HL-S1-A (one booster per driver)
• 1 × rotary wall dimmer — HL-TS-K(WT)

Optional later (not required to dim from the wall): HL-R6-1 or HL-R11. Those remotes need pairing. They are not plug-and-play.

How the dimming is wired

The hybrid driver can dim in several ways (mains / TRIAC, 0–10 V, 1–10 V, PWM, resistance). This layout uses mains (phase-cut / TRIAC) only. Ignore the other dimming inputs on the driver for this job.

1. Each 5 m / 4 m section has its own 300 W hybrid driver on the 24 V side. Follow the wiring diagram in the Attachments tab on the driver page.
2. Each driver is fed on the mains dimming side through its own HL-S1-A booster. The booster keeps the dimming signal strong when one wall dimmer is driving three large LED loads.
3. The input / dimming-signal side of all three HL-S1-A units connects to the single HL-TS-K(WT) wall dimmer. One knob dims the whole 14 m line.

The HL-TS-K(WT) needs Live and Neutral. It is not a classic one-wire (two-wire) dimmer. If the site only has a one-wire dimmer loop, that is a different design and must be checked separately.

The same wall dimmer can also talk to the Tuya / Smart Life phone app and to RF remotes, but those extras need pairing and a competent installer. You can use it as a normal rotary dimmer only, with no app and no remote.

Layout on site (14 m = 5 m + 5 m + 4 m)

1. Lay the three pieces end to end in the profile so the joints are tight and the line looks continuous.
2. Leave the copper of each piece isolated from the next. No solder bridge, no clip joining 24 V between sections.
3. From each driver, inject 24 V at both ends of that section.
4. Cut the last roll only on a factory cut mark to make the 4 m piece.
5. Give each driver ventilation and cable sized for the current of that section (about 8.3 A at 24 V for a full 5 m / 200 W).

Cool-white option

The same power and dimming package applies to the 6000 K sister tape if the project needs cool white instead of 3000 K: HL-COB-24V-CW-40W-IP00. Do not mix colour temperatures on one visible line.

Installer’s note

Cut only at marked points. Test each section before closing the profile. This 40 W/m 30 mm COB needs professional installation: correct cable, ventilation, independent feeds, and the Live + Neutral dimmer circuit.

Disclaimer

Hi-Line Lighting supplies products only and does not provide on-site installation, technical consultancy, or a full lighting design service. This article is general guidance for a typical 14 m, 40 W/m, 30 mm COB layout. All calculations, wiring, safety checks, and regulatory compliance must be carried out and verified by a qualified installer. Incorrect design or installation can cause overheating, equipment damage, or fire.

If you do not have a lighting designer and need help on a larger or more complex project, contact us. We can put you in touch with trusted external partners.

Need help with a similar project?

Email [email protected] with the run lengths, CCT, and whether you have Live + Neutral at the switch. If you receive an automated reply with a ticket number, keep it. If you do not receive that reply, please call to confirm the message arrived.