Home Security Lighting – Timers and Switching
Home Security Lighting
A photoelectric cell will switch on a lamp when the amount of light detected by the cell falls below a predetermined level; it will turn off the lamp when the amount of light rises above the preset level. A photoelectric cell normally incorporates a time delay to prevent the lamp from being turned on by a sudden drop in light level caused by fast moving, dark rain clouds or by passing car headlights. In other words, the cell will only switch on the light when it’s needed.
Photoelectric cells are very reliable and require little maintenance, other then a periodic wipe with a damp cloth. For more precise control, you can buythat incorporate both a photoelectric cell and a timer. That way, you can ensure that the light can only be turned on at certain times of the day.
Passive Infra-Red Detector
A passive infra-red detector (PIR) operates by sensing the movement and change in level of infra-red energy within its field of view. It doesn’t ‘look’ at the entire area within its range, but detects infra-red energy from a pattern of smaller zones. This means that the detector is more sensitive to movement across its field of view than towards it. Security lights bought at DIY stores usually combine this type of detector with a spotlight or floodlight containing a tungsten-halogen lamp. Most people install the light fitting on the back wall of the house and aim it down the garden.
One of the problems with this arrangement is that the detector can’t tell the difference between a neighbour’s cat and a burglar. Consequently, the powerful light could be switched on and off needlessly on many occasions, which could reduce the life of the lamp. Nevertheless, the combination is very useful, and by adjusting the angle of the PIR, you can reduce the rate of ‘false’ switching. If you tilt the PIR downwards, only close approaches to the house will be detected; alternatively, reducing the angle will mean that the detector looks over the heads of any local cats. However, if you set the angle too high, you could pick up cats walking along the top of the back fence. Some PIRs have quite a wide angle of view, making it possible for your neighbour to switch the light on from their garden. It’s a matter of finding a suitable compromise. Some models allow you to adjust the sensitivity of the PIR.
Timed and Manual Switching
Time switches simply turn the lights on and off at the times you set. They must be reset periodically to stay in line with seasonal changes. A disadvantage of a time switch is that a power cut could make it lose its time setting, requiring it to be reprogrammed. It is possible to buy a time switch fitted with a solar dial that incorporates either an electronically wound clockwork motor or an electronic motor with a spring reserve. This allows the unit to run for a number of hours without electrical power.
Some people may prefer simply to switch on the lights manually when it gets dark. This works well provided there is always someone at home to do so.
A house in total darkness during late afternoon in the winter makes an obvious statement that no one is at home.
An alternative is to have a combination of automatically switched lamps with one or two that are manually switched. For example, a tungsten-halogen lamp fitted to the back wall of a house could have its switch in an upstairs bedroom. This would allow the back garden to be observed from a vantage point behind the bright light source, which hides the observer. In this way, you would have total control over the light, only switching it on if needed to do so.
Indoor Timer Switches
To complement outdoor security lighting, don’t forget the security lighting inside your home. A wide variety of indoor timer switches are available from DIY stores, including some that plug into a wall socket or a standard ceiling light fitting; others can be fitted in place of a wall light switch. Most cater for 24-hour programming for up to seven days with random on/off switching. Some incorporate a battery back-up in case of power failure. Alternatively, you can buy battery operated sensor lights that function in a similar way. When using these switches, it is important to distribute them around your home so that the lights are turned on and off in a manner that reflects your normal domestic routine.
For most people, this means turning lights on in the lounge, dining-room and kitchen from when it gets dark until bedtime, with additional timed lights coming on in the bedrooms and perhaps the bathroom later in the evening. It’s a good idea to have lights showing to the back and front of your home. It’s essential to make your home look occupied. Lights left on only in the hallway and on the landing at, say, 10pm might actually suggest that nobody is at home.
Going on Holiday
If you don’t have timers for your lights, ask a trusted neighbour to pop in each evening and turn some on (and off again later). Even if you do have timers, it’s important that your neighbour comes in each day to draw the curtains so that when your timed lights come on, you’re not showing everyone in the street (including potential burglars) the contents of your home.
Your neighbour could also pick up any post or junk mail that has been delivered and that tends to mount up against the door – a real give-away to the burglar, especially if there is a glazed panel in the bottom half of your front door.