The words lighting flicker alone bring on a headache. Of course we all have visions of a dodgy fluorescent lamp in a ceiling dying a slow death of low frequency cycling. However it is avoidable – it is not inherent in all artificial lighting – and with a little knowledge you can manage the problem.
5 things you need to know about lighting flicker
1. All lighting flickers.
You do not need to be an electrician to get this bit – an AC power supply that we all use modulates usually to a frequency of 50 or 60 hz or double mains frequency. This causes the source of the light to turn on and turn off at this rate – fast enough to appear visually smooth.
2. Discernable flicker can be detrimental to health
According to studies a low proportion of humans are susceptible to flashing lights which can trigger ailments and seizures but lesser known is that long term exposure to unintentional flickering of 70 to 160 hz can cause visual impairment and migraines. Research has shown the retina in the eye can pick up frequencies of 100 to 150hz unbeknown to us, potentially a contributing factor to ‘sick building syndrome’ – offices that for a number of factors see a high propensity of illness.
3. Is LED more prone to flicker than other traditional sources?
An important question with a complicated answer, as LED lighting can be powered in various ways – e.g. with constant current and constant voltage drivers, and without drivers with direct AC power. BUT what we want to know is if it’s safe to use? The fact that solid state LEDs are a fast cycle technology and effective at being completely on and then completely off – so this will increase the sense of flicker unless handled. Traditional sources such as tungsten even when on the OFF cycle still emit some light, creating a smoother light. This is where a good LED driver has a job to do to minimise this effect.
4. Does dimming increase the sensation of obstructive flicker?
It depends on how the dimming is done but yes it can.
a) Dimming a light can be done by reducing the amount of power it receives.
This is done by chopping off some of the AC cycle of power – creating a wider gap between ON and OFF which can begin to be seen by the eye unless dealt with by the correct type of dimmer module. So without good compatibility between dimmer and light – flicker will occur.
b) Dimming an LED can be done by Pulse Width Modulation – like a TV screen that flashes many frames per second giving the eye a smooth transitional between each frame, i.e. it’s too fast to discern. By turning the power on and off fast enough, less power is used so the light is dimmed – but if not fast enough strobing will be apparent.
5. There is no national standard defining what rate of flicker is unacceptable.
In the absence of a universally definable level of noticeable flicker, it does feel we are exposed to making mistakes when specifying. At Orange lighting our approach is to buy and deliver the best quality LED driver whenever we can – on all projects, sourcing from manufacturers who have given this issue consideration.
As lighting suppliers and consultants we are aware that flicker exists in all lighting, particularly when dimming. However, good compatibility between dimmer, driver and LED – through testing – will keep this issue under control.
Call us to discuss this issue and we will guide you through the measures that will avoid flicker in your next project.
It’s that age old problem that bites us when we least expect (and cruelly) during the final installation phase of a project. For all of us who specify and design lighting – glare is a real problem – the need to provide sufficient light onto an object with the minimal amount of discomfort to the user’s eyes.Arguably the best lighting is where the cast of light is seen and not the source. However, unless completely shielded – light will inevitably be bright at source and likely to shine glare into the eye. Spotlighting is an application where designers have to be particularly careful.
Top tips to minimise glare if a fixture isn’t concealed:
1. Ensure the beam angle of the fitting isn’t unnecessarily wide – This avoids
extraneous light hitting the eye and directs light only to where it is required.
2. Choose a lamp or source (typically an LED) that is recessed into the fitting. How? Use a baffled fixture – which has a short tube/cylinder construction (typically black) – by sinking the source deeper into the fitting the spill of light is minimised
3. Add a snoot – Odd word for another tube added onto the front of a spotlight. This deepens the source thus hiding it further – reducing the angle of light that may trouble users vision.
4. Add a honeycomb louvre – Some fixtures provide the option for this – simply hiding the source from the eye at a wider viewing angle.
5. Be aware of unprotected LED chips behind lenses – The current trend
toward the miniaturisation of fixtures utilising LED’s small proportions brings with it a potential downside. Maximum output is achieved if the bare LED is behind a lens but it’s very harsh to the eye and must be used with care.
Lastly – if in doubt – dim the fitting but that is only supplementary and not a fundamental fix.
When you specify and purchase lights from us – this advice is all part of the extra value service we offer all our clients. So if you wish to light your next project with total confidence – call us and we will be happy to help!
Now – is this solely the territory for the lighting geek OR is this really relevant to you?
It’s actually a key principle to understand to help your lighting designs go from good … to great.
In this short video Andrew gives you 5 practical tips to aid you in this process.
1. Choose what you are lighting – is it simply the floor or a piece of furniture or maybe an architectural element?
2. Light spreads increasingly wider the further it leaves it’s source – so how wide would you ideally want the spread of light to go by the time it hits the lit surface?
3. Calculate the distance – between light source and that surface.
4. Now draw to scale – this distance with the source at one side and the rough desired spread on the other.
Draw a line from the source to the edges of the desired lit width – the angle between these two lines is our chosen beam width.
5. Now select a lamp or fixture – with a beam width as close as possible to that value.
Remember too that light is also used and chosen to highlight objects all along it’s pathway
For example – if you use a floor light to uplight a column – you’ll want to keep the beam width tight and follow the line of the architecture from the moment it leaves the source carefully considering how wide it will spread along it’s path.
Another great benefit to purposefully choosing your angles of light also helps combat the glare that light can bring to the eye.
So let’s start taking control and next time you choose your lighting – not only think of us here at Orange Lighting – but consider those beam widths.