Why Are My LED Lights Flickering (and How to Fix It Fast!)

Ever had a “simple job” turn into an hours-long headache? A few years ago, a ROBUS team member was troubleshooting flickering on a ground-floor lighting circuit. After hours of fault-finding, the cause turned out to be a poor connection amongst a group of downlights hidden above the ceiling and tied into the same run! It later became clear they’d been deliberately concealed to increase the dimmer load and bring it into its compatible range. The client didn’t even realise those hidden lights were drawing an extra 50W—with no usable light to show for it.

It’s an unusual fault, but it highlights something important: flicker isn’t always where you expect it to be, and without a clear process, it’s easy to lose time chasing the wrong cause. In this article, we’ll walk through a practical step-by-step checklist to help you find and fix LED flicker fast.

Start with the Most Likely Causes for Flickering Lights

1st Check: Loose Connections

Loose terminations are one of the most common causes of flicker. When a connection isn’t tight, the metal-to-metal contact can be poor or intermittent (and can even arc slightly under load). That increases resistance and causes unstable voltage or brief interruptions in supply, something LEDs and drivers show as flicker. If you’re very lucky, a lamp may just need a small twist to seat properly. If not, here’s how to locate the cause…

How to Check

Isolate and prove dead. Then re-check the whole loop: at the switch (common, switched live, neutrals if present), at each fitting (especially neutrals), and in any junction/maintenance-free connectors. Look and feel for loose conductors, browned insulation, melted terminals, or a “hot” smell. Re-terminate as required, then load-test and confirm the flicker is gone.

Common Hotspots: First fitting on the run, last fitting (loose loop-out), switch back box, any connector hidden above ceilings, and any borrowed/shared neutral points.

2nd Check: Dimmer Incompatibility

Dimmer incompatibility isn’t just about wattage, it’s about how the dimmer controls the power, and how the LEDs and/or driver reacts to it. Older leading-edge (triac) dimmers “chop” the mains waveform, which can make some LED drivers buzz, shimmer, pulse, or drop out—especially at lower dim levels. Some LEDs need a trailing-edge dimmer, or a completely different control method (e.g., 0–10V or DALI), so the LEDs and dimmer must be matched.

How to Check

To begin with, confirm a dimmer is actually in the circuit! Then bypass it temporarily (fit a suitable switch link or test with a working non-dim switch) and retest for flicker. If the flicker disappears, it strongly indicates that the dimmer is the source of the problem. This means the flicker is not caused by the LED fittings or wiring, but rather by incompatibility between the dimmer and the LED load.

The next step is to check if the dimmer is the right type for the LEDs (leading-edge/triac vs trailing-edge), confirm it is rated for LED use, and ensure the connected load falls within the dimmer’s minimum and maximum specifications. Where possible, test with a dimmer model listed as compatible by the LEDs/driver manufacturer.

Common Hotspots: “Universal”/old triac dimmers, multi-way (2-way/intermediate) dimmer setups, smart dimmers, and dimmers without a neutral (more prone to nuisance behaviour at low loads).

3rd Check: Minimum Load Issues

Dimmers, drivers, and even smart switches often specify a minimum load to operate correctly. If the connected LED load is too small, the control electronics may “hunt” (constantly searching for a stable operating point and over-correcting), causing shimmer, pulsing, or flashing—especially at low dim levels. Even if the LEDs meet the minimum load at full output, dimming down reduces the power draw. If the load drops below the dimmer’s minimum operating level at low settings, the dimmer can struggle to regulate the LEDs smoothly, resulting in flicker, pulsing, or sudden jumps in brightness near the bottom end.

How to Check

Add up the actual connected load on the dimmer/driver (LED wattages or driver output load), including any fittings on the same switch line. Compare that total to the dimmer/driver’s stated minimum load. If you’re under the minimum, test by temporarily adding load (where appropriate) or by swapping to an LED-rated dimmer/driver designed for low loads.

Common Hotspots: Only 1–2 LED fittings on a dimmer, very low dim settings, no-neutral smart controls, and circuits where extra fittings were added/removed over time (load no longer matches what the dimmer was originally sized for).

4th Check: Driver Mismatch

Flicker can come from an LED driver that’s the wrong type or is being pushed outside its operating range. Common issues include using a non-dimmable driver on a dimmed circuit, mixing constant-current and constant-voltage components, or exceeding driver limits due to too many fittings. Alternatively, low-quality drivers can introduce flicker even on a stable supply due to poor internal regulation.

How to Check

Identify the driver type and rating (constant current vs constant voltage, output range, dimmable/non-dimmable) and confirm it matches the fittings on the circuit. Check for overload (too many fittings) or underload (outside the driver’s operating range). If the circuit is dimmed, confirm the driver is dimmable and compatible with that dimming method. Swap in a trusted, correctly rated driver to confirm.

Common Hotspots: Non-dimmable drivers on dimmer circuits, mixed driver types on the same control, long cable runs causing voltage drop on 12/24V systems, and incorrect replacement drivers fitted during maintenance.

5th Final Check: Supply Stability

If everything checks out, consider the supply. Voltage fluctuations, shared circuits, or interference from other loads can all cause LED flicker—even when the fittings and controls are correct.

Now You Know How to Stop LED Lights from Flickering

The best way to avoid flicker call-backs is to start with proven, compatible gear. Stick to trusted manufacturers (like ROBUS!), follow the stated dimmer/driver compatibility guidance, and keep the load within spec. Then the only flicker faults you’ll be chasing are the special case Friday-afternoon head-scratchers.