DALI dimmable Luminaires with Class II LED modules: why it is not recommended to use them

In recent months, customer demand for luminaires with Class II LED modules and with DALI dimmers has increased, something which Airfal’s technical department advises against due to the lack of guarantees for their correct use.

To understand better the situation, it is important to know what a Class II luminaire is.

Class II luminaires are characterised by additional safety measures such as double insulation or reinforced insulation. This type of insulation is mainly intended for manual electrical appliances, where extra insulation is required as they are used by people for many day-to-day activities.

Thanks to this double reinforcement, it is not necessary to use a ground connection when installing luminaires with Class II insulation. They do not depend on space conditions, which means a significant saving of time and, above all, of money when installing them.
However for some electrical appliances and installations it is recommended to use Class II insulation, such as lighting in the interior of a swimming pool. However, the use of Class II is not recommended for luminaires with LED modules and DALI dimming.

The elimination of the grounding of the installation can cause various electronic malfunctions and this implies several drawbacks and for that reason Airfal advises against this practice.
In the case of luminaires with LED modules, the reduction of Electromagnetic Interference (EMI) cannot be guaranteed by suppressing the earth connection, so it is not possible to comply with the relevant regulatory requirements. On the other hand, the grounding of LED luminaires ensures that the phenomenon of “LED GLOWING” or ghost lights does not occur. This phenomenon occurs when the luminaire with LED modules continues to emit a residual light when switched off or on standby. In the case of Class II luminaires, it is impossible to guarantee that there will be no “LED GLOWING”.

On the other hand, in the case of transients or voltage/current peaks in the power supply network, the presence of grounding causes the filters of the LED drivers to act by reducing or eliminating them. Without the presence of an earth ground connectionn (Class II), any transient will pass through the driver and reach the LEDs, shortening their life span or even destroying them.
We see in this graph a simple explanation, being the left part without grounding, and the right part with grounding:

On the right-hand side with earth connection the transient arrives much more damped than on the left-hand side without earth connection.

In the case of Class II DALI luminaires, it must be explained that DALI drivers are very sophisticated devices controlled by a small internal computer. The control and regulation of the LEDs is carried out under the supervision of a software integrated in the driver microprocessor.
For the correct operation of these devices, the computer that incorporates it needs to “measure” the reference potential 0. Without grounding, the measurement may be inaccurate, and the dimming may fail or have uncontrolled random effects (Current differences between luminaires, synchronism faults…). We can find cases of correct operation in which regulation problems may appear after some time.

In addition, the standard governing a DALI installation (IEC 62386) specifically specifies the need to have an earth connection to protect the control circuits and drivers, as shown in the following figures:

As stated at the beginning of the article, the lack of guarantees for quality, uninterrupted lighting is the main reason why the installation of Class II, LEDs and DALI dimming is not recommended.

How to adapt  lighting when growing older

Over time, our eyes become more sensitive and react more strongly to light. It is therefore necessary to do some adjustment in the lighting of the house in order to maintain a good quality of life and sight. Space can become more comfortable even when the signt changes with age.

How does the perception of light change with age?

Changes in vision can occur throughout life, but once you reach a certain age, these changes become even more worrying than simply not seeing objects from a distance. Just like the rest of the body, some muscles of the eye begin to weaken. Have you ever shined a light in one eye and watched the pupil dilate? The muscles involved in this phenomenon are intended to control the quality of the light collected and, as we get older, they find themselves lagging in their reaction time. This implies that the eyes take longer to adapt to dark or bright environments. Other changes may occur such as yellowing of the lens that affects the perception of colors, the appearance of spots or “floating” in the vision caused by particles in the vitreous of the eye and cataracts that cause areas of fog in the eyes. Medical measures may be takento repair these phenomena or improve these conditions, but good lighting may also help to compensate for some of these eye disorders.

What kind of light should be installed to adapt to these changes?

Intense light

The troubled vision due to age can often be solved by simply using more light than usual. This does not necessarily mean that you have to raise the brightness of all the lighting in your home to extreme levels, but you can use bright lights for some tasks, such as table lamps, floor lamps, lighting under cupboards to provide more lighting for activities such as cooking, reading or using the bathroom mirror, etc. That being said, it’s not necessarily a bad idea to increase the general level of lighting in your home.

Ambient lighting

As mentioned above, older eyes have difficulty adjusting to different levels of light as quickly as before. In order to bring as much comfort as possible to the eyes, you need to set up uniform ambient lighting throughout the house. This means that no room should be brighter or darker than another, so there must be smooth transitions from one room to another. The addition of dimmers (dimmers) can also make it easier to adjust light levels in different rooms.

Anti-glare light

The glare of the extremely powerful light emitted by the light bulbs can trigger vision problems and even worse, “eye floaters”. These eye floaters and other eye injuries can cause light scattering in the eye. This increases the sensitivity to glare, which is not the case for low light levels. To avoid glare, make sure your light sources are shaded or not directed directly to the eyes. For example, you can use spots with frosted lenses to hide the light source.

Precision of color

Because the coloring of lenses on the eyes may change, it is important that light sources have a very high CRI or CRI (Color Rendering Index) – usually above 80 – for colors to be more authentic.

Tips for buying LED bulbs

First of all, there is no real comparison between LED bulbs and other conventional light bulbs (halogen, incandescent, compact fluo and others).

Indeed, it should be noted that not all LEDs have the same lighting power and that some of them alone can have a luminous flux equivalent to more than 500 LEDs less powerful.

The most efficient and economical light bulbs are now the LEDs, but they are not bought like a conventional incandescent bulb or even halogen. Here are some of our tips for making the right choice.

With incandescent bulbs and halogens, we speak had to deal with watts (W), since their luminous intensity depends on their power consumption. This is no longer the case with LEDs. For example, a 6W high performance LED illuminates as well as a 60W incandescent bulb or 46W halogen. The central LED information is the lumens (lm). Read more

What is Human Centric Lighting ?

So as  to understand what is human-centric lighting, LightingEurope, an industry association representing leading European lighting manufacturers and national lighting associations,  and the International Association of Lighting Designers (IALD) have issued a joint paper in which they defined the benefits, technologies, and potential applications.

They  define “Human Centric Lighting” as a form of lighting that goes beyond colour rendering and power efficiency but instead takes into account  other non-visual effects, including circadian-tuning. Read more

Outdoor lighting for parks and public gardens

Lighting of parks and gardens should focus on the safety of pedestrians walking on the trails through the park. Lighting must allow pedestrians to discern obstacles or other hazard , and give them the opportunity to see other pedestrians. Waterproof light fixtures shall be used for such purpose.

Light sources
Parks and gardens generally require white light in order to obtain a better color rendering. The white light provides improved visibility for pedestrians. Therefore, metal halide lamps with ceramic arc tube or the white LEDs are great options.

Recommended level of lighting for a park
Lighting in park areas shall meet recommended levels, and also minimize light pollution and intrusion on neighboring properties. The lighting level can significantly impact on the appearance and safety of the park at night. The high-pressure sodium lamps, a commonly used source for urban light, cast a yellow-orange light that gives poor color rendering; this light challenges the visual clarity and considerably impairs the overall quality of the night urban environment. In contrast, metal halide lamps diffuses a soft white light that makes colors more accurate; they provide better visual clarity, and require less power for the same perceived visibility. The light quality is also influenced by the amount of light – or more precisely, by the relationship between the brightness of light and the distance to the light source. The light becomes more diffused as we are farther from the source, so that for a given brightness, there are heights where we should place the light source to create the desired light quality. Read more

Recommended lighting  levels for offices

Light Level or Illuminance, is the total luminous flux reaching  on a surface, per unit area.  Lighting systems in offices  are usually  designed based on the light levels or illuminance required by the tasks performed within each working area .

Office spaces are often over-lit as a result of using outdated lighting fixtures. These older lighting systems were  designed to accommodate paper-based reading tasks , that usually needs  light levels of 500 to 750 lux. Today’s work at the office  primarily involve computer based tasks, and the lighting levels can range from 300 to 500 lux.

We should bear in mind that having the  right lighting requirements onto a task area such as a desk is only one of the elements that has to be considered in the overall lighting project. Indeed,  the whole working environment should be taken into  consideration: the impact of lighting  onto the walls,  and across the space has also to  be considered, so as to create a pleasing and productive working atmosphere. It is recommended to avoid  any sharp  change in light levels within an office space as this will cause the eyes to have to continually adjust, resulting in eye  fatigue, and affecting negatively the productivity of workers.

What is the recommended lighting level for offices?

The below  table represent light level recommendations for office areas.

Areas and activities Intensity Recommended Lux 
Accounting office High 500 – 750
Office in general Medium 250 – 500
Waiting room Low 150 – 400
Reception desk Low – Medium 300
Computer work station Low – Medium 300 – 500
Meeting room Medium 500
Technical drawing High 750

 

An infographic analyzes the overall energy efficiency of LED bulbs

An infographic by Chadwicks analyzes the overall energy efficiency of LED bulbs, from manufacturing to the end of its useful life.

The infographic compares compact fluorescent lamps, incandescent lamps, and LEDs. The infographic analyzes different items such as lifespan, energy consumption during use, the energy used to manufacture …

According to the infographic, if a LED lamp requires 9.9Kwh to be made, compared to an incandescent lamp that needs 0.612Kwh, the LED bulb spends much less energy, which leads to greater profitability.

While LED bulbs are more expensive, they have a longer life (between 50 and 100,000 hours for LED lamps, versus 1,000 hours for an Incandescent light bulb). Another advantage is that LED bulbs have to be changed less frequently than incandescent lamps.

Infografia-eficiencia-led

How lighting could affect our emotions and behaviour

120Neuroscience researchers have been investigating the influence of light intensity and color temperature on human’s mood and behaviour.

The lack of light is usually thought to affect the mood: it can lead to the condition known as seasonal affective disorder, or winter depression. However, recent studies by North American researchers show that both positive and negative emotions may be intensified by brighter lighting, while lower lighting may dampen those moods. Contrary to popular belief these researches show that depression-prone people actually become more depressed on sunny days.

Other similar correlation measures the effects of different colors of light on human’s mood and behaviour and how these can affect the body in different ways. Read more

The cost of lighting – infographics

Here is an infographics from the website lamps.com, featuring the cost of using incandescent light bulbs, CFL bulbs (comact fluorescent bulbs) or LEDs.

The average lifespan of a led is 50 times longer than an incandescent light bulbs. Price is also significantly higher, even nif LEDs are getting cheaper 

However, we have to bear in mind that incandescent light bulbs are less used than in the past. In the USA, incandescent light bulbs are disappearing In 2014. In Europe too, incandescent light bulbs are being phased out. By switching to compact fluorescent bulbs,  companies and industries can reduce their negative contribution to climate change and save money at the same time.

The initial higher cost is quickly recovered, as these bulbs use only a quarter or a fifth of the electricity used by incandescent bulbs, and last much longer. Over its lifetime, a single compact fluorescent bulb will save you approximately 250 $, and their price is decreasing.

cost of lighting