The Crime Prevention Website


By using a variety of switching devices to control your external and internal lights you can reduce your electricity bill, reduce your personal carbon footprint, reduce the adverse impact of lighting on the environment, make it look as if you are at home when you are out for the evening and provide a welcoming lit entrance for when you come home after dark.   This part examines the variety of switching devices that will deliver these advantages. 

Wall switch

Don’t dismiss the simple wall switch, because it certainly has its uses.  It is particularly useful for switching on external floodlights that if repeatedly switched by a passive infrared detector might annoy the neighbours. (See Side and rear gardens in this section)  They can also be used to switch on the garden lights from inside the house to investigate a noise you might have heard.

Photoelectric cell switch (Dusk to dawn)

Any lights that you want to switch on for all or some of the night can be controlled using a photoelectric cell switch.  The simplest of these devices turns the light on at dusk and switches it off at dawn.

The easiest type to use is a device that sits between a lamp holder and the lamp and therefore requires no wiring at all.  Its use may be limited to a simple ceiling light, a table lamp or perhaps a porch light.  Many can be used with compact fluorescent lamps.  Some of them include timers so that when the light is switched on after dark you can set it to turn off again some hours later. (See  Lighting, Internal lighting for the home )  In effect this is a secondary switch that sits between the lamp and the wall switch.

Another type is a light switch replacement, which incorporates a photoelectric cell that will switch the light on when it gets dark, but you can also use it as a normal wall light switch.  Most also incorporate timers so you can adjust the amount of time the light will stay on.  They are very simple to install.

A third type is an independent device which can be positioned away from the actual lamp its operating. Obviously it needs to be wired using the services of an electrician. I've got this type and it works very efficiently.  

Timer switch

Timer switches allow you to turn lights on and off at precise times during the night and are available as replacement wall switches or plug-ins.  They are offered with a variety of different timing functions from 24 hrs up to 13 days so you can randomise the times your lights come on and go off each day. (See  Lighting, Internal lighting for the home)

If you don't like the idea of wiring in a new timer wall switch or bending down to use the plug in timer there's now a new product on the market which is used in conjunction with a square wall light switch that doesn't require wiring.  It's called the 'Light Switch Timer' and it's the first of its type.  Basically you loosen the screws on the wall switch in order to hang the cradle and then tighten the screws back up.  You then pop the battery operated timer into the cradle. It has all the usual timing functions and on the back of the device are small wheels that run across the light switches, turning them on and off.  I've got one and it works very well indeed.  Go to our DIRECTORY to find out more about this particular product.

Switched-On Products  

A new Essex-based company has announced the UK launch of the first ever automatic light switch timer to fit over an existing wall light switch, without the need for any wiring.

“The problem I personally found with using lamps on timer plugs was that the light given off didn’t look realistic, making it look more obvious that no one was home”, says Naiem Dakri, director of Switched-On Products.  “Unfortunately, the timers which fitted onto wall light sockets needed to be wired in, usually by an electrician, which certainly put me off bothering to buy one”.

It was this observation which led Dakri to create a product which could be fitted to the existing light switch on the wall without the need for any rewiring.

“During the development of the product, we found a similar patented product in the US, we formed a strategic partnership, to enhance the product to work on UK-style rocker switches.  The new UK product shares the same manufacturing facility as the widely sold US model”, he says.

 The battery-operated “Light Switch Timer” can be used in any living space which gives off the most light, deterring would-be intruders.  It works by sliding a cradle over the wall light switch, into which is slotted the control unit, making it ready to operate in seconds.  It includes program on and off times for different days, to suit the individual’s lifestyle.

The device has been designed to operate effectively on all standard, single, double or triple gang light switches, and with all light bulbs, including LEDs and CFLs.

“I created Light Switch Timer specifically to act as an effective security device for those people who either live alone, don’t return home until the evening or have a holiday planned and want to be sure their house remains secure”, says Dakri.  “It provides a mid-market security solution which helps to keep energy costs down, too”.

Passive infrared detector (PIR sensor)

A passive infrared sensor is an electronic device that measures infrared light radiating from objects in its field of view. A PIR sensor, used as a motion sensor for a lamp or an alarm, detects a change in temperature across its field of view, such as that caused by an animal passing in front of another infrared source of a different temperature, such as the lawn.  PIR sensors used for this purpose do not measure the temperature of the entire field of view, but instead collect temperature readings from a series of fingers of detection.  They are therefore more sensitive to close approaches and have a detection limit of about 25 metres.  They are generally more sensitive in cold weather when a small warm blooded animal can be detected against very cold ground. 

They are commonly used to operate external lights around the home, including tungsten halogen floodlights.  They are also used in two stage lighting for the communal parts of blocks of flats whereby a lower level of lighting is supplemented by additional lights that are triggered by the PIR as someone enters the building.  Likewise they are used frequently in office lighting systems throughout the day, so that the lights automatically switch on and off in the presence (or not) of office staff.  This ‘intelligent’ form of lighting saves an enormous amount of energy.   You can also buy replacement wall switches for the home that incorporate PIRs and timers for the same effect as the office lighting system.  I’m thinking about buying a couple as my lads are forever leaving lights on!