Cut LED strip lights at the circuit boundary and keep the offcut usable

CHECKPOINT / 01

Confirm that the exact variant is cuttable

Look for scissors marks, dashed cut lines, copper pads and a documented cut interval. The interval depends on voltage, circuit grouping, light engine and sometimes the addressable control design. A strip without a visible or documented cut boundary should be treated as not ready to cut. Some COB variants support a much finer or free-cut pattern, but that behavior belongs to the specified variant, not to every COB strip.

• Photograph the cut marks before the strip is installed.
• Record the cut interval in millimetres and in the project length plan.
• Keep the reel and offcut labels together until the circuit is commissioned.

CHECKPOINT / 02

Measure the real path and mark it

Measure the channel, corner, cable exit and service loop together, then mark the nearest valid cut line. Do not stretch a flexible strip to make up a short measurement, and do not cut at the end of a reel simply because the length looks right. For an addressable strip, also preserve the data direction and leave enough pad area for the connector or solder lead.

• Add the width of the joint and end treatment to the fit check.
• Keep the data-in arrow on every digital offcut.
• Power down and disconnect the reel before bringing scissors or a knife to it.

CHECKPOINT / 03

Make a square, low-force cut

Use a sharp tool suited to the strip and cut through the marked line without twisting the PCB. A crooked cut can remove part of a circuit or leave one side without enough copper for a joint. Keep the silicone, coating or phosphor surface clean, and expose only what the selected connector or solder method requires. Inspect the two ends before reconnecting them.

• Cut through the center of the marked copper boundary when the drawing calls for it.
• Avoid crushing the board or pulling components from the cut section.
• Do not scrape across adjacent pads or bridge them with loose solder.

CHECKPOINT / 04

Reconnect the offcut as its original interface

Choose the connector or solder method from the light engine and pad map. Match positive and negative, preserve channel order and keep addressable data flowing from output to input. After the electrical joint works, add mechanical strain relief. For a coated strip, the removed coating at the joint must be replaced with a suitable end seal or housing; cutting does not make the new end waterproof.

• Use the correct pin count and width for the offcut.
• Test a repaired section before adding sealant or closing the profile.
• Keep a short spare lead when the joint will be inaccessible later.

CHECKPOINT / 05

Test before the finish hides the mistake

Power the original section and offcut separately first, then test the joined run at low and maximum planned brightness. Check the first and last LED group, channel order, data direction, voltage and temperature. For outdoor or wet applications, inspect the complete end treatment, cable exit and drainage plan as a separate approval. A strip that lights on a bench is not automatically a durable finished assembly.

• Verify every channel or pixel group after reconnection.
• Measure voltage at the far end under a repeatable bright state.
• Record the final cut interval, joint method and seal method.

FAILURE MODES

What usually goes wrong

• The strip is cut between circuit marks because the measured length is slightly shorter.
• A COB free-cut claim is generalized to a conventional or different COB variant.
• The cut removes the copper pads needed by the selected connector.
• An addressable offcut is joined backwards or with an incorrect data path.
• The end is tested electrically but left unsealed in an exposed installation.

TECHNICAL BASIS / VERSION

Keep the decision current

This guide is maintained as a versioned technical record. Recheck the current protocol documentation and the exact product revision before using it in a production installation.