Why is my LED lamp flickering? Wattage labels, loads, and LED driver efficiency made easy

Why is my LED lamp flickering? Wattage labels, loads, and LED driver efficiency made easy

When fitting an LED dimmer, the job should be no more difficult than wiring the mains to the terminal, installing the adaptor, and assembling the frame and plate.

However, as seamless as Zano’s products make this process, you wouldn’t be here if you hadn’t encountered a bit of resistance from your lamps.

You might be wondering “why aren’t my LED lights working?” or “why is my LED lamp flickering?”.

Fortunately, it’s not likely to be a lamp problem. In fact, with Zano’s controls, an LED lamp that won’t turn on is likely a safety feature, not a bug.

It all has to do with your load. Let’s get your LED lamps and drivers working again.

Why do LED lights flicker? Watts on the label are the likely culprit.

Quality LED lamps should run silently with no . If they don’t, or they simply won’t turn on, there’s likely not enough .

Remember, inrush is that surge of initial current that a lamp requires to turn on.

What you might be forgetting when trying to control a flickering LED lamp is that the inrush current is rarely included in the wattage on the product box. This wattage only accounts for the power of the light without considering the efficiencies of the entire fitting.

Solution: leave a generous inrush allowance. We’ve seen lamps regularly quadruple their labelled wattage, with some 5W/VA downlights reaching 20W/VA. However, this disparity is the exception rather than the norm. LED lamps from reputable manufacturers spike only slightly above their labelled wattage.

If you are able to do so, have your lamps tested before fitting on site (it’s one of our 4 steps to successful dimming.) 

Dimmable LED lamps flickering still? Remove the guesswork with load calculations.

If you don’t want your inrush allowance to be a guessing game, you’ll benefit from doing a simple load calculation. It’s not difficult, we promise.

You simply need to calculate the VA (the load) from the wattage and power factor.

For LED lamps (low wattage lamps or small downlights up to 10 watts) take the wattage on the product box and divide it by the power factor from the fitting spec.

Tip: remember that ‘power factor’ is simply how efficiently current is being transformed into useful output – that which lights your lamps. It should always be on the spec document for your lamp.

Since power factor is always less than 1, this sum will always produce a positive value (your load) - and no flickering LED lamps.

LED drivers, efficiency and how to stop dimmable LED Lamps from flickering once and for all.

The power factor being less than 1 is a matter of an LED lamp’s efficiency. The same goes for ‘heavy-duty’ LED drivers. These have a much higher wattage than LED downlights as they power multiple lamps or runs of LED lighting – hence why we can’t fit these behind a plate on a wall (yet).

It’s a deep topic to explore if you all you want to do is get a flickering LED lamp under control, so here’s all you need to know about LED driver efficiency:

  • LED drivers are ‘rated’ at the amount of energy they can deliver – not the total energy being drawn in the circuit.
  • An LED driver’s efficiency is normally best when loaded to 80% of its total ‘capacity’. That being said…
  • A driver’s data sheet will show you the efficiency of the load you’re going to connect in the form of a graph. This will help you decide on the optimum driver for your LED fittings.
  • Lastly, don’t forget about power factor when calculating your load.

Controlling high wattages and inrush – you can only do it with the ZBARLED.

As you would expect, the fewer fittings you’re controlling, the simpler your load calculations will be. As the number of fittings in your circuit grows, so will the need for a driver, and the need to account for LED driver efficiency. Without the right controls, it makes dimming a seriously tricky job.

The only product on the market that can control these high load drivers is the ZBARLED. It’s a remote dimming pack that can handle multi-point dimming at high loads (over 250W/VA, and ) – all on a single circuit.

It works with up to 32 Zano rotary controllers to provide flicker-free and silent dimming, and for the most demanding loads, they can be wired in parallel. It takes the guesswork out of dimming, and it’s nothing short of groundbreaking.

So, that’s how to stop dimmable LED lights from flickering. Don’t be fooled by ‘watts on the box’, don’t stress about inrush with simple load calculations, and always remember to account for LED driver efficiency with higher loads. If in doubt, the ZBARLED can almost certainly handle it.



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