Mythbusters: LED Dimming

Mythbusters: LED Dimming

Mark Lewin from Zano Conrols helps us bust a few commonly believed myths about dimming.

LED dimming didn’t exactly get off to the best start. Early adopters of LEDs faced a near impossible task when it came to dimming, with terrible lamp tone and incompatible technology combining to create an underwhelming first impression, on installers and clients alike.

Yet, while everyone knows that LEDs have come a long way since those ghastly bright-white downlights, misconceptions are still rife around LED dimming, with many installers still perceiving LED dimmers as inflexible, unreliable or just downright ugly.

Here, we bust a few popular LED dimming myths – from flicker and buzz to mixed loads on a single circuit.

Myth#1: Just use a standard analogue dimmer
Technically, a TRIAC dimmer will dim an LED – but it won’t be pretty. You might luck out and find that at certain levels, the light output is consistent and comfortable, but it’s unlikely to give you the same range as a digital dimmer. This is because TRIAC dimmers operate under a current interruption method that reduces power to the lamp, thereby lowering its light output, while LEDs run on a continuous forward current. That current interruption, which is imperceptible when an analogue dimmer is paired with a Tungsten lamp, becomes visible when twinned with an LED driver.

Besides, does your customer really want to mess around every time they switch on the light to find a level that doesn’t flicker? Probably not.

Myth#2: The label never lies
It’s a contentious subject, but independent testing has found a huge disparity between the wattage listed on an LED’s box and the power it actually consumes. An LED’s inrush current – that surge of energy as a lamp ‘powers up’ – is often not included in the wattage on the label. In our testing lab, we’ve seen lamps regularly double their labelled wattage, with one 12 watt lamp reaching 32 watts.

Aside from misleading consumers over the potential energy reduction of switching to LED, this huge difference in wattage can wreak havoc on your dimming installation. The total wattage of 10 12watt lamps is well within the comfort zone of a 0-300W dimmer, but 10 32watt lamps is a very different story. In this case, it’s not the dimmer causing the problem: it’s the lamp.

“At Zano, all of our LED dimmers can support an unlimited number of lamps as long as the circuit’s combined wattage remains within the recommend amount…”

Myth#3: You can only dim 10 lamps on an LED dimmer
Many LED dimmers will only support a limited number of lamps, regardless of the total wattage of the installation. A lot of early LED dimmers capped this number at 10, and this figure seems to have stuck in the minds of LED installers, with many still believing that more than 10 lamps will require a second, or potentially bespoke, dimmer to be added to the circuit.

Yet there’s no longer any real reason for a limited number of lamps, as long as the right technology is used. At Zano, all of our LED dimmers can support an unlimited number of lamps as long as the circuit’s combined wattage remains within the recommend amount; ie, under 1000W for the ZBARLED0-1000W.

Zano Controls-pic-2

Myth#4: You can’t mix incandescent and LED loads
This is a tricky subject, because in many ways LED and incandescent loads don’t mix. That said, they’re not entirely incompatible on a dimmable circuit, depending on the lamps and dimmer used. A digital LED dimmer designed to support a large LED load, like the ZBARLED 0-1000W, can be used to dim LED and incandescent on a single circuit. In theory, as long as the overall wattage of the LEDs and incandescent lamps combined – factoring in drivers and in-rush current – doesn’t exceed the dimmers limit, the two technologies can be paired on a single circuit.

Myth#5: Low level dimming is always a nightmare
One of the queries our technical team deal with most frequently is dimming at low levels. Many off-the-shelf dimmers have a dimming range of 10W+, which might be fine for a circuit of six 4W downlights in a sitting room, but can’t support lower loads. Electricians often encounter dimming issues with smaller LED circuits, such as an en-suite bathroom or a small hallway, which at their lowest levels can easily dip below 10W, causing the lamps to flicker or simply drop out.

While it’s seen as an unavoidable problem, there’s actually a simple solution: just look for a dimmer that allows installers to adapt the load accordingly. Zano’s ZBAR products start at 0W: perfect for those tricky low loads.

Zano Controls-pic-3

Myth#6: Flicker and buzz is unavoidable
Some installers might accept a slight flicker or a bit of buzzing at certain levels as part of their dimming installation: don’t be one of them. There’s no reason that, with a good quality lamp and a digital dimmer, an LED install should flicker or buzz. For the end user it’s more than irritating, with prolonged exposure to LED flicker causing various problems, from headaches to eye strain.

Some lamps just aren’t able to support a full dimming range and will produce flicker at either high or low levels, but you don’t need to put up with it. Either switch to lamps with a better performance or fit a dimmer that allows you to set minimum and maximum level presets yourself (and save your client fiddling around trying to find a comfortable level after you’ve left the job).

For more information visit:

Related posts