Led Downlights, Flickering & Dimmers

We receive a number of enquiries about flickering led downlights which can become very apparent in some situations and dimmer compatibility. It’s a complex problem that sometimes cannot be fully resolved.

Why can’t the flickering always be resolved you might ask?

Let’s have a look briefly at the fundamentals behind the problem.

The uptake of led technology has been rapid for a number of reasons including improved energy efficiencies reducing electricity consumption and lower overall running costs.

Following on from the rapid conversion to energy-efficient led lighting in recent years the flickering problems have become more prevalent.

Previously we used filament type GLS lamps which were purely a resistive load and contained no electronic components. In the majority of cases, they worked perfectly with an electronic dimmer.

However, if we now combine led light fittings which contain electronic components (transformer drivers) then we now have two sets of components that don’t always match correctly leading to load compatibility problems.

Additionally, some dimmers have a minimum connected load requirement to correctly control the associated equipment.

Other factors that can cause nuisance flickering include external interferences upstream from the electrical installation including some inverter (DC) driven air-conditioners, inductive motor loads, grid supply problems, and off-peak “Zellweger ripple control relays”

Supply authorities injected signals into the grid remotely usually at the 11kV substation level to control off-peak hot water services and some utility lighting.

Zellweger ripple control relays were first deployed in Australia in the 1950s as a means of load shedding meaning typical 4.8 kilowatts (20 amp) hot water service elements heated at night when the grid supply-demand was lowest.

In essence, the Zellweger ripple control relay is just a big switch rated at 25 amps per pole which are remotely controlled.

Supply authorities’ inject these control signals at various times during any 24 hour period but it becomes more prevalent at night because that is when Off Peak-1 Tariff (most common tariff) is signalled to switch on anywhere from 10.00 pm and off again typically by 6.00 am.

The flickering symptoms typically can include minor buzzing noises with fans, flashing led downlights that detect these signal pulses causing the electronics to malfunction.

In severe cases, the led downlight can display stroboscopic responses requiring the downlights to be turned off.

These injected signal pulses can last upwards of 90 seconds and be repeated again at varying sequences.

Different distribution supply areas have different signalling pulse times therefore the times that these signal pulses are sent can vary significantly.

Led downlights comprise sensitive electronic components and as such become erratic in operation when subjected to electrical frequency variations and external interferences.

There are devices/filters readily available which can counter or reduce these external influences which can counter acting as a load correction device.

From our experiences load correction devices work in some instances to balance (filter-out) these external interferences whilst in other circumstances we have had to change the dimmer module and or selected led downlight fitting.

Finally, it is worth noting that when experiencing flickering led downlights try adjusting the dimmer control knob slightly higher or lower in the setting. Sometimes one particular setting can be more sensitive to the external frequency interferences.

In summary – contact us if you need further assistance though please remember there isn’t one straight answer to resolve these types of flickering problems rather it sometimes comes down to a “trial and error” approach to either resolve and or reduce the severity of the problem.