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 |
|
