Dimmable Fluorescent Lighting And Home Automation

One of the first things you will want to do using home automation is to dim all your controlled lights to preset levels to set the so called scene. One problem is that you can't dim a fluorescent light fixture.

The main reason is that dimmable home automation modules work by sending signals through the bulb and in a fluorescent light there is a ballast resistor that prevents this also the fluorescent light is actually similar to a controlled lightning arc i.e. very high voltage and it will fry any digital (low voltage) electronics attached to it.

Some background on fluorescent lights

A fluorescent tube works by heating liquid mercury until it becomes a vapour and ionizing a gas (usually argon). The ballast device produces extremely high voltage to kick start the ionization process (and once started the voltage falls back to a low level).

Note: This is why the tube flickers on start up - the automatic switch within the tube electronics detects if current flows and re-tries the start process until it does.

Once started the tube settles at its own current level limited by the ballast device. This current level depends on the design of the ballast device and the AC current frequency 120Hz and the specifics of the tube - all these are fixed.

Since the tube contains mercury never break open a fluorescent lighting tube mercury is poisonous (but there is only a very small amount inside).

One of the reasons the fluorescent tube is so popular is that it is extremely efficient since once the arc is created inside the tube (and it generates ultraviolet light) the white coating on the inside fluoresces due to the ultraviolet and radiates visible light. This process generates no heat so most of the electric energy is converted to light.

In comparison a normal light bulb (incandescent light) is designed to operate by burning a metal in an inert gas and this generates lots of heat as well as a little light.

Note: A fluorescent light is about 5 times as efficient as a normal bulb (this is also why you can buy a 15W flourescent that outputs the same light as a normal 60 watt bulb.

Dimmable fluorescent light

Because of the way the fluorescent lights work you can not dim them but you can use an appliance module to turn them on and off. An appliance module has a relay inside that switches the power to the fluorescent bulb independently from the home automation electronics so that the sensitive electronic circuit is protected.

There's more information about X10 and dimmable fluorescent lights on the website.

John Main's website http://www.easy-home-automation.com shows you how easy it is to control electronic devices within your home by using affordable home automation modules.