LED Lights Troubleshooting Guide

LED strip lights flickering

Flickering is almost always caused by one of four things.

Incompatible dimmer switch — traditional trailing-edge dimmers cause the driver to flutter, producing visible flicker especially at lower dimming levels. Fix: replace with an LED-compatible dimmer and check the minimum load rating against your total strip wattage.

Loose connection — a loose connection at any point in the circuit causes intermittent current flow. Fix: with the power off, remove and reinsert every clip connector. Check that copper pads are fully aligned with the connector pins.

Undersized or failing driver — a driver at or below the total strip wattage will struggle under load. Fix: measure total wattage (length × W/m) and compare to driver output rating. The driver should be rated at least 25% above the strip wattage.

Voltage drop on long runs — on runs longer than 5 metres from a single feed point, the voltage at the far end drops enough to cause flickering when dimming. Fix: add a second feed point — end-feed from the driver to both ends, or mid-feed to the centre of the run.

LED lights not turning on at all

Check mains supply to the driver — is the driver's mains indicator light on? Use a multimeter to test for 230V at the driver's mains input terminals. If there is no mains voltage, check the fuse or circuit breaker and any intermediate switching.

Check the driver output voltage — test across the driver's output terminals (marked + and −). You should read 24V for Lumily LED drivers. If the driver shows mains input but 0V output, the driver has failed and needs replacing.

Check polarity at the strip — LED strips are polarity sensitive. Reverse polarity will result in no light but will not damage the strip — if nothing lights up, swap the connections and test again.

Check for a damaged section — visually inspect the full length of the strip for any section that looks blackened or physically damaged. A short circuit at any point will prevent the whole run from lighting. Cut at the nearest cut point on each side of the damage and use a connector to bridge the gap.

LED lights dimmer at one end

This is almost always voltage drop. The strip at the driver end is receiving the full 24V; by the time the current has travelled to the far end, resistance in the copper conductors has reduced the voltage enough to noticeably affect brightness.

To confirm: measure the DC voltage at the driver output, then at the far end of the strip. A difference of more than 0.5V indicates significant voltage drop. To fix:

• End-feed — run two-core cable from the driver output directly to the far end of the strip, connecting in parallel.
• Mid-feed — for very long runs, connect the driver to the midpoint of the run rather than one end.
• Heavier cable — increase the cross-sectional area of the cable between driver and strip.
• Second driver — for runs beyond 10m, using two drivers (one at each end) is often the cleanest solution.

LED remote not working

• Dead battery — replace the battery (usually a CR2032 coin cell).
• IR remote, obstructed line of sight — infrared remotes require a clear line of sight to the receiver. Move the receiver to a more exposed position.
• RF remote needs re-pairing — press and hold the pair button on the receiver until the strip flashes, then press any button on the remote to re-pair.
• Wrong controller type — an RGB controller will not work with a single-colour or CCT strip, and vice versa. Confirm the controller type matches the strip wiring.

LED lights showing incorrect or inconsistent colours

• Missing colour channel — check the connection at the controller output for that channel and the connector pins on the strip. A single pin not making contact will cause one channel to be absent.
• Controller set incorrectly — reset the controller to factory settings and try again.
• Wrong wiring order — RGB strips from different manufacturers are sometimes wired in different channel orders (RGB vs GRB vs BGR). Check both manufacturers' specifications.