Useful security devices or self-deception?

A homeowner's quest for peace of mind can be confusing, time-consuming and costly. Richard Phillips considers the latest in burglar-unfriendly equipment

Modern technology has come to the aid of the homeowner in the fight against crime and fire, as ever more sophisticated devices are peddled to the security conscious.

But do these alarms make much difference ? Or is installing them, at best, no more than a self-deceptive gesture towards peace of mind?

Although crime figures suggest a small reduction in break-in rates, there is still one burglary committed every 30 seconds.

For those who have suffered at the hands of burglars, it is usually a shattering experience. As well as losing valuables, there is the trauma of having had your home invaded, and often the loss of items of great sentimental value can be far more distressing than the theft of cash or electrical goods.

The police are strong advocates of alarms to protect against crime, and the first thing to do is to call in your local crime prevention officer for advice.

Not all flats or homes would benefit from an alarm, and a crime prevention officer is among the best-placed to give you impartial advice. What's more, it's free.

The police won't advise on individual brands, but they will discuss the generic types of alarm available, and what is most suitable to your circumstances.

Alarms are now available in a bewildering array of designs and detection techniques. At the bottom end of the market, you may hope to get away with some change out of pounds 100; Wickes' cheapest own brand starts at pounds 69.99 including VAT for a do-it-yourself system, but from there on, prices range up to several thousands of pounds for more advanced systems.

As Mike Ritte of New Scotland Yard's crime prevention bureau explains, an alarm must have two effects: it should act as a deterrent to the intruder, and it must, if activated, be able to alert the police directly, as well as having a siren to alert neighbours and occupants.

Thieves fall into two categories: the opportunists, and the professionals. The latter are usually the hardest to beat, although opportunists can be very determined. Most break-ins occur between 3pm and 4pm, when the occupants are at work, or picking up the kids from school. The next most common time is when owners are away on holiday.

Experts say there is little point in putting up a fake alarm - professionals can usually spot them instantly - although one would be better than nothing at all.

One thing to keep in mind is that one of the biggest problems for the homeowner and the police is the "false alarm" syndrome. Last year, a crackdown by the police was launched to combat this now endemic problem, which is the bane of many a street, with unwelcome alarms more of a nuisance than a deterrent. Alarms should meet local environmental regulations on noise, and automatically switch off after 20 minutes.

There are now some 250,000 alarms installed each year, but it is estimated that there are three million false alarms each year. Only 250,000 calls a year are genuine. Now, after four false calls, the police send a warning note to the household and, if the problem persists, they will refuse to attend your home "until all other emergencies have been dealt with, allowing for the available manpower".

The key to avoiding false alarms lies in the installation, and the Association of Chief Police Officers has laid down guidelines for registered companies to follow. For this reason, DIY kits are frowned on. "They cause mayhem and havoc," said one police officer. But, while the DIY option is at the bottom end of the market, it can still have a deterrent effect.

Companies which are members of NACOSS - the National Approvals Council of Security Systems - are required to meet its guidelines.

Most alarm systems rely on infra-red sensors which detect heat emissions. A burglar in the room should trigger them.

But infra-red sensors are extremely sensitive and changes in room heating can set them off, so they may have to be programmed precisely to your needs. You may want the alarm set automatically for the night time - in which case it should be set to cope with someone getting up in the night to visit the kitchen without the entire system having to be shut off and then reset.

Other sensors include low-level microwave emitters which use the Doppler effect. This is a low-tech radar; if the microwaves are interrupted by someone walking through the field, the sensors detect the change in pattern and trigger the alarm. Ultrasonic soundwaves are also used for this purpose.

For a simple bell-only alarm installed by a reputable company, the typical cost starts at about pounds 300.

The next step up is the alarm system connected to a monitoring station. Contrary to popular myth, such alarms are not connected directly to a police station, but are monitored by private security companies. Here costs can escalate quite sharply. As well as an annual monitoring fee, the company will often insist on twice-yearly service visits, for which it will also charge.

Finally there is a wacky array of other hi-tech gizmos coming on to the market, designed to target the thief. A smoke system can emit clouds of dense but harmless smoke into a room where an intruder has been detected.

Another system relies on miniature cameras to send photographs of any burglar back to the monitoring station.

There is even one company which can install electric fencing, although this walks a fine line between your duty to protect other people, be they trespassers or not, from coming to any harm.

You should also consider using security lights for any areas around your house where a burglar could lurk. The cheapest ones are little more than pounds 15 or so from a DIY store.

Or you could install timer switches for your lights or television, which ensure that lights come on at preset times, creating the impression there is somebody at home.

The last security device required in the home is a fire alarm. These are relatively simple, and the local fire brigade will provide advice over the phone. It is only if you have an unusual lay-out to your home, with perhaps mezzanine floors, that a home visit may be useful.

Smoke alarms are recommended for most homeowners; fire alarms are the more sophisticated variants, which have an array of sensors throughout the home which are connected to a bell. But these are only of help in larger properties that are stacked full of expensive furniture.

For most of us, according to the fire service, the standard smoke alarm provides ample protection.

A smoke alarm should be installed on the ceiling - smoke rises - and, ideally, there should be one for every floor.

Do not install one in the kitchen, as the fatty smoke from the grill or burning toast can easily set them off.

To make sure you are buying a reputable brand, check that it displays the British kite mark on the packaging.