| Home security is a
subject close to many peoples’ minds. As the years go by we all build up
collections of valued possessions. Insurance is all very well, but it
won’t replace those items with sentimental value or make you feel any
better about intruders violating your home. If you can stop them getting in,
you have protected more than a house full of possessions. You have protected
your family’s way of life. It need not cost much to protect your home and you do not have to be an expert to fit a security system. If you can wire a three-pin plug, you can learn how to fit a burglar alarm. Your initial decision is to choose between a hardwired system or a wireless system that uses low power radio circuits to connect the sensors to the main alarm unit. Each system has its own features and benefits:  Pros Hardwired alarm systems rely on simple switching circuits to operate, so they are easy to understand. They do not need complex electronics, so they can be inexpensive to buy. They run from one main power supply, so they do not need several batteries periodically changing. Wired alarm systems do not use radio signals, so their arm and disarm codes cannot be ‘cloned’ by enterprising technological criminals. Cons Hardwired alarm systems need to have cables run from the main control panel to each window, door or motion sensor and there are a number of ways to connect them together for correct operation. Care must be taken to keep the wiring well away from any place where burglars could tamper with it, disconnecting sensors from the system.  Pros Wireless alarm systems have no cables connecting sensors to the main control panel, so they are extremely easy to fit and do not create redecoration work. Nearby sheds or garages can be covered without the need for external cables. They are controlled by convenient keyfob remote control units, with no complex disarm codes to remember. Some wireless systems even have solar-powered wireless external bellboxes.  |
| Cons Each sensor has its own battery and these must be monitored and changed periodically, but many wireless control systems will let you know when a battery is getting low. Some wireless systems still use a wired external bellbox connection for added reliability. With very specialised receiver/decoder equipment, it is possible (though very unlikely) that transmitted arm and disarm codes may be ‘grabbed’ and ‘cloned’, or transmissions may sometimes be jammed so that the panel cannot receive sensor alarm signals.  As the name suggests, hardwired systems rely on wired inputs to inform the main control panel what is going on in your home. The most fundamental part of a wired alarm system is the ‘closed loop’. This simply means that, all being well, the control panel expects to see a short circuit between two sense terminals. It passes a signal to one end of the loop and expects to see it come back at the other. If any door or window fitted with a sensor is opened, a magnetic switch in the sensor opens and the loop is broken. So, in essence, all that you need to do is to fit a sensor to each window or door that you wish to protect, run a cable back to the panel, connect the mains supply and bell box and presto! Your home is secure. In practice, there is a bit more to it than this, but it is not too complicated.  The sensors connected to an alarm panel could all be wired up as described previously to a single input on the control panel (called a zone), but there are advantages to having several zones covering different parts of the house. Firstly and most obviously, you can tell what part of the house the sensor is in if the alarm is triggered. This narrows down the search for signs of an intruder or an open window. Having several separate zones rationalises the wiring too, as you end up with several spurs of wire running out from the control panel to each part of the house, instead of one huge loop that must pass through every room, upstairs and downstairs. The use of separate zones allows you to ‘part arm’ the system. At night, the lower floor could be armed, with upstairs bedrooms disarmed so that windows could be left open in summer. In addition to the normal zones that you use to cover the different parts of your home, there are often extra zones dedicated to special functions. The 24 hour zone or anti-tamper (confusingly often referred to as ‘tamper’) zone will be triggered if anyone attempts to cut the wiring or dismantle the control panel, the bell box, or any of the sensors connected to the system, whether the alarm is armed or not. Likewise, you may fit a panic button to the 24 hour zone or |