D.I.Y.
FITTING A WIRE-FREE ALARM SYSTEM
The simplest type of alarm to fit is the wireless (wire-free) system. Each detection unit, PIR or CONTACT is fitted with a radio transmitter, containing its own internal dry battery, capable of sending a unique coded signal to its CONTROL UNIT. Each unit signals alarm conditions and TAMPER faults to the control unit via the built in radio transmitter.
The system CONTROL UNIT is wired to the mains supply and to the outside sounder.
A few outside sounders are also wire free, and are charged via built-in solar panels.
A pocket sized, radio operated remote control setting and unsetting device, also incorporating a personal attack button is also usually available.
The system is relatively quick to install and does not require much more than a screwdriver. Each unit is usually programmed to work with the control unit, before being finally fixed in place, but this is quite straightforward.
Most systems have a "low battery "indicator on the main control unit and the systems are quite reliable as long as batteries are changed yearly. Very long life 9 volt batteries are now made for smoke alarms (5 to 10 year life). These may be suitable for wire free systems. Consult your manufacturer.
The main drawback is the high cost of each unit compared with a standard wired type, and the size of each unit, as they contain a transmitter and battery, although some modern units are very much smaller than the older types.
The availability of spare parts must also be considered. Additional detector units must be compatible with the system. In a conventional hard-wired system, almost any make of detector can be fitted allowing the system to be maintained almost indefinitely. The cost of generic PIR’S and contacts (switches) is also very low compared with wirefree devices.
The handbooks on some wire free alarms often leave a lot to be desired, so ensure that a help line is available at a reasonable cost.
Advantages of wire free alarms is that they are relatively easy to move from premises to premises, and out buildings are easily connected to the main system, as long as they are in transmitter range of the main control unit.
On a lot of wirefree systems, (Friedland etc.)on setting the system, always check that doors etc. protected by switches, are shut as no indication is given on the control panel that a door is open and the system will set with the door not protected, unless the intruder shuts the door and opens it again!
FITTING A HARD-WIRED ALARM SYSTEM
A large selection of do-it-yourself intruder alarm systems is available. Sources are DIY stores, such as B&Q, Wickes, Focus and Homebase and specialist shops.
The ideal supplier should be able to give advice if a problem is encountered—check this before you buy. A good source of advice is worth a few pence on the price, as unlike electrics and plumbing, burglar alarm literature does not really exist, and most alarm companies will not be interested in helping out the amateur alarm installer.
Display picture courtesy of STAN HOULDEN, THE SECURITY CENTRE.DIY ALARM EQUIPMENT etc.,Middlesbrough 44(0)1642 241151
THE ALARM CONTROL UNIT
Each detection device needing a source of power to run it should be on a separate zone or circuit. The zone is usually labelled c/c loop, zone 1,2,3 or similar. There may also be a tamper zone for each zone.
The + and - are the 12 volt supply to the detector(usually a PIR). The c/c (closed circuit) loop is the part that creates an alarm condition. When the alarm is set this loop is closed circuit, hence c/c loop. When the PIR, door contact or other device is triggered, the loop is broken, thus setting off the alarm. Apart from making a lot of noise, the control unit will indicate what zone or circuit has operated via an LCD (liquid crystal display) or LED (light emitting diode) display, or in some cases, in older systems, a panel light marked with the appropriate zone (circuit)
A CC (closed circuit) loop operates totally opposite to a torch switch or bell push. A bell push or torch switch is an O/C open circuit device. That means that in normal (off) circumstances no connections made between the two ends. When the bell switch is pushed, or the torch is turned on, the connection is completed, thus sounding the bell or lighting the torch.
This principal is simple but has a major flaw. If the connections between the switch and the bell or bulb is cut or broken, the unit will appear OK, but will not work when the switch is operated, as a circuit will not be completed.
This would be a minor inconvenience for a front door bell or torch, but could have serious consequences for a security alarm.
The closed circuit system used in almost every alarm installation means that if the connection on the detector circuit is damaged or faulty, the alarm will trigger, or if not set,the relevant TAMPER zone will operate or the zone will not be clear when an attempt is made to set the alarm system. This is another good reason for having each detector on an individual zone or circuit. Fault finding is much simpler!
As an added safeguard, most control units have an additional closed circuit zone known as a TAMPER. This is similar to the C/C loop. Tamper loops must be closed (connected) whether the alarm is set or unset. If the loop is broken at any point the alarm will sound, usually internally only, if the system is not set, when they are broken. On some control boxes, the tamper circuit may give separate indications of which zone is faulty.
The tamper loop is to indicate a cut cable or tampering with detection devices 24 hours per day. PIR’S have 6 connections. + for 12volt positive connection, - for 12 volt negative connection, C/C loop {closed circuit} (PAIR), for the alarm operating connection (zone 1,2,3,etc.) and S/P (single pole) loop (PAIR) or tamper, for tamper protection (cable cut or cover removed from PIR unit. These are connected back in the main alarm control unit in the appropriate positions. If the lid or cover is removed from the PIR, even when the alarm is not set, a tamper alarm is sounded, and an appropriate indicator is operated on the main control unit. The same alarm condition will be triggered if the connecting cable to the PIR is cut.
To silence the tamper alarm, the user set/ unset code has to be entered on the alarm control unit. On older key operated control boxes the key switch usually has a tamper silence positionto allow work to be carried out on the system,without disturbing the neighbourhood!
Contacts or switches are fed by a 4 core cable(4 wires in one cover). One pair of cables forms the C/C (closed circuit) loop connected across the contact. When the switch is operated(open circuited) by the door etc. being opened,the loop is broken,causing the zone or circuit to go into an alarm condition. The second pair of cables are connected in the contact in the form of a loop and is connected back to the circuit tamper.This is to give immediate notification if the connecting cable is cut or tampered with, even with the system turned off. When a problem is found on a zone the fault can be isolated by connecting the two loop connections with a loop of wire in the alarm control unit. If the zone is then clear(set), on the control panel, the fault is on the external zone or circuit, and the control unit is OK. Make sure that only like poles are linked together, as a connection between a + and- could damage the control unit.
Use a long piece of wire as a temporary loop, and let it trail out of the control box. This should make it difficult to accidentally leave a circuit or zone disconnected. It is always a good idea to test an alarm control panel by looping out(connecting the two terminals together with a loop of wire) the zones and tamper connections, prior to wiring in the external circuit cables. After testing the control box, do not forget to remove the loops!
N.B-On more sophisticated Alarm Control Boxes an end of line resistor is used to increase security. When looping out zones or loops with this type of system, use a spare resistor of the correct resistance.
Do not run alarm cables parallel to mains cables as mains spikes may be induced into the alarm cable and cause a false alarm. Mains spikes can be caused by fluorescent lights, washing machines, Hoovers,central heating boilers etc.
24 HOUR ZONE OR CIRCUIT
A 24-hour zone is a facility that may be programmed into some alarm control units. If they are used for window foil, C/C wiring etc., they will sound the alarm as soon as they are broken, to allow repairs to be made before the system needs to be set. When the system is set, they operate exactly the same way as other night zones or circuits. A 24-hour zone may also be used on stockrooms needing a level of protection during alarm unset periods. A 24 hour zone has the advantage of having OMIT or ISOLATION facilities, to allow the protection to be turned off.
ENTRY/EXIT ROUTE (ACCESS)
The exit route circuit is usually the final door that is closed when leaving the premises, or the first opened on entering the premises.
In most modern control units the exit route can be any circuit or zone, and is programmed in at the time of installation.
The exit route circuit is operated by at timer device, set to around 20 to 60 seconds, to allow the operator to pass through the exit zone protection and leave the premises before the alarm sets fully.
Once the exit setting sounder has stopped, when the last door is shut, the alarm is fully set. The exit zone will not cause an alarm condition as soon as it is triggered, but it will start the entry EXIT TIMER. If the correct code is not entered into the alarm control box within the pre set entry time, the full alarm will sound. Because of this, it is good practice to keep the amount of detection on the exit circuit to a minimum. On police calling systems DD243 specifies special conditions for exit route circuits. A proximity key fob is now used extensivly to unset sytems.
EXTERNAL SOUNDERS
Most external sounders also work on the closed circuit principal, and contain their own rechargeable battery supply.
A 12 volt supply goes to the outside bell or sounder. This can be labelled OBA, (outside bell apparatus)
SAB (self-actuating/activating bell) C/C bell or similar. The unit needs a constant 12v supply. Removing the bell supply will cause the sounder to operate.
Most modern external sounders are also fitted with a strobe type flashing light to attract attention to the sounder. It is a matter of opinion if the strobe should continue flashing after the outside sounder has stopped,or continue until the system is turned off.
The 12-volt supply from the control unit keeps the battery within the sounder charged.
If the cable to the sounder is cut or tampered with, the bell hold off is removed, and the sounder will start up and will sound independently of the main alarm control unit, being powered by its own internal rechargeable battery( ni-cad or miniature sealed lead acid).
Older types of sounder had a 12-volt supply from the control unit to charge the battery and keep the sounder silent. and a tamper loop to protect the cable.
OPEN CIRCUIT SOUNDERS
An open circuit sounder, usually a bell, operates the same as a front door bell, and sounds when a voltage is supplied from the alarm control box. This is not as secure from tampering as a self-actuating or closed circuit type.
INTERNAL SOUNDERS
Internal sounders are usually of the open circuit type, like a front door bell, and sound when the control unit triggers into an alarm condition. They are fitted to the O/C bell or sounder connection. This connector supplies 12 volts in an alarm condition but no voltage in a normal condition.
The sounder can be a bell, but is usually an electronic sounder that produces a considerable volume of shrill noise.
A mains operated open circuit device, usually a siren, can also be used, triggered by an isolating relay, supplied with its activating voltage by the alarm control unit and switching a supply of mains voltage via isolated relay contacts to the siren.
PERIMETER PROTECTION
If an alarm system is required, that can be set even when the premises is occupied, a system of contacts (switches) and VIBRATION DETECTORS can be fitted to all the external doors and windows. This is more costly in time and materials, and is more suited to larger houses and bungalows, and should not be necessary for the average household. CONTACTS (PROTECTIVE SWITCHES)) as well as VIBRATION DETECTORS are needed on opening window sections, as a window left insecure would allow entry into the premises, without triggering the vibration detectors.
The advantage of a perimeter alarm is that it can be left almost completely on even when the premises are occupied. This is convenient for larger houses, especially bungalows, with elderly residents, or pets. The increased labour and equipment will increase the cost of a perimeter alarm system.
A vibration detector should not be fitted to the front entrance door.
In case the reason for this is not clear,think of a person knocking on the door or slamming the letter box!
A useful site for more practical help. I do not endorse all of the suggestions.
This site gives practical fitting advice, but I would never put more than one PIR on a single Zone---you will be sorry!!
http://www.letsfixit.co.uk/html/burglar_alarms.html
If you want to install window FOIL, the guide below will be of interest.
http://www.alarmfoil.com/install.htm