The ability to adjust the amount of artificial light in space should not be overlooked, on a grey rainy day you will want to supplement the lack of natural light - it's the day so our mind expects light. Conversely, as the night falls and we settle down to eat, listen to music or watch TV, the light we need and desire is less. switching stuff off achieves this but on/off is not the only option.
Many decorative dimmers switch plates on sale around the UK retail sheds use basic dimmer inserts - they are after all built to a price. If your dimmer is not working on dimmable light fixtures or dimmable bulbs you might want to replace the dimmer module with something better suited to the task. Nearly all decorative or coloured wall switch plates use dimmer modules and if your switch plate has a round knob, behind which is a threaded spigot with a nut, you can swap this out for something better. Simply undo the nut and swap the wires from your poor-performing dimmer and use one of those below.
Best advice - ensure the load (the total wattage of all your bulbs added is within the range of the dimmer.
Expert advice - always use a professional dimmer module - some bulbs and LED fixtures still play-up on quite good modules. Professional dimmers provide the best chance of success as they allow you to adjust the minimum and maximum loads and Smart dimmers allow you to switch between dimmer technologies to get the greatest flexibility and smoothest operation.
Dimming Methods - tips and advice
There are two main dimming methods today. Each of these is suitable for different types of loads (see below):
Leading Edge Dimming - the early part of each sine half wave is chopped off. These are suitable for:
- All resistive loads
- All inductive loads
You cannot use leading edge dimmers for capacitive load transformers unless the transformer states, "Suitable for leading edge dimmers" although "dimmable with most dimmers" is a good sign too!
Trailing Edge Dimming - the latter part of each sine half wave is chopped off. These are suitable for:
- All resistive loads
- All capacitive loads
Do not operate inductive loads on this kind of dimmer - this will usually destroy the dimmer. Resistive loads are suitable for both dimming methods. However, Trailing Edge Dimming offers a softer mode of operation for the lamps and will extend lamp life. Please note that some of the cheaper trailing edge dimmers in the market are only suitable for resistive loads. Please also refer to the recommendations by the manufacturers of lamps and other controls.
So what type of load do I have? Resistive loads = mains voltage incandescent lamps and halogen lamps Inductive loads = 'Old School' heavy wound or laminated transformer used for low voltage halogen lamps
Capacitive loads = electronic transformers or converters for low voltage halogen lamps
Dimming of Low Voltage Lighting Wire wound transformers - All wire wound transformers are dimmable. Electronic Transformers are not so simple to classify. Some are not dimmable at all, some need a leading edge dimmer, some need a trailing edge dimmer. Check manufactures details with your product or present your electrician with the transformer and ask them to provide a suitable dimmer module.
Why does dimmed lighting sometimes hum, and how can it be corrected? Because of the way all dimmers deliver power at settings other than full brightness, the filaments inside a light bulb may vibrate when lighting is dimmed. This filament vibration causes the hum. To silence the fixture, a slight change in the brightness setting will usually eliminate bulb noise. The most effective way to quiet the fixture is to replace the light bulb. As far as the `bulb singing` concerned, a bulb consists of a series of supports and, essentially, fine coils of wire. When the amount of current flow abruptly changes the magnetism change can be much stronger than it is on a simple sine wave. Hence, the filaments of the bulb will tend to vibrate more with a dimmer chopping up the wave form, and when the filaments vibrate against their support posts, you will get a buzz. If you have buzzing, it is always worth trying to replace the bulb with a different brand. Some cheap bulb brands have inadequate filament support, and simply changing to a different brand may help. Note buzzing bulbs are usually a sign of a "cheap" dimmer. Dimmers are supposed to have filters in them. The filter`s job is to "round off" the sharp corners in the chopped waveform, thereby reducing EMI, and the abrupt current jumps that can cause buzzing. In cheap dimmers, they have economized on the manufacturing costs by cost-reducing the filtering, making it less effective.
Buzzing problems with dimmers Each good dimmer has a filter choke inside. The chokes also help to eliminate `lamp singing` that can cause audible noise to come from the lighting fixtures. In providing those filtering functions, the chokes themselves can generate a slight buzz. A little bit of buzzing is normal with filtered dimmers. If the buzz from dimmer can be a problem it is recommended that the dimmer is placed in the area where this buzz will not be a problem.