How Alarm Works and Installation Tips



A Security Alarm System is made up of Electronic Equipment installed in a building OR a property to warn the following of an unusual event or circumstance:

>  The Residents

>  A Central Monitoring Station who can then send the appropriate Response including Security, Police, Fire or Ambulance

>  The Owners and / or Contact List 

>  Neighbour’s

>  Passers By

Components making up a Security Alarm System 

>  The Control Unit powered by a Mains Power Supply

>  A Backup Battery to provide 12V DC Power when the Mains Power goes off

>  Keypads and / or Remotes, these are specific to the brand and model / version of Alarm Controller 

>  Detection Equipment

>  Internal Siren

>  External Siren

>  Communication Equipment, usually an Analogue Auto-Dialler built onto the Control Circuit Board


Standard Settings on Security Alarm Systems 

>  Adjustable entry delay zones (usually 20 -30 Seconds)

>  Adjustable exit delay (Usually 60 seconds)

>  Adjustable siren run time before resetting (usually 3- 5 Minutes)

>  Selectable entry zones

>  Selectable chime zones

>  Selectable night arm setting zones (also called Stay zones, short for Stay at Home zones)

>  Selectable 24 hour zones

>  Fast Arm Feature 

>  Panic function on keypad 

>  Medical function on keypad

>  Fire function on keypad

>  Duress Code function on keypad (The panel sends through a “Duress” code to the monitoring station as well as an unset code)

The User

>  Arm / Disarms via the keypad by entering a valid user code (usually 4 Digit) 

>  Can part arm the alarm (especially useful in a residential alarm so it can be part armed at night)

>  Can change, add and delete user codes easily.

>  Can isolate or bypass  zones using the Zone Isolation feature,   

>  Can have individual user codes for each user (one for each key holder is a good idea as the owner can then identify who has set and unset the alarm, especially      useful in business alarm systems)

Terminology that is Commonly Used

Passive Infra-Red Detector (PIR for short)

PIR is the shortened term used to describe a Passive Infra-Red Detector. Approximately 95% of the detection equipment used by the security industry is Passive Infra-red detectors, commonly referred to as PIR’s. They are reliable, aesthetically attractive and if the appropriate detector is used for the environment that it is installed in and it is installed to the Industry standards are reliable.

PIR’s measure the movement of a heat source against the background ambient temperature of the area they are installed in, and if the difference is greater than pre-set parameters will activate. PIR’s emit a series of Infra-Red beams like fingers on a hand and at various height levels. The number of beams, their coverage pattern and range vary for each make and model of detector, and the lense used. 


Tamperproof is a common term to indicate a wiring configuration so that if any wires are cut or have been tampered with the alarm panel will activate irrespective as to whether it is set or not, 24 hours of the day.

Tamper Switch

Tamper Switch is a term to describe a switch that opens when a cover is removed from a detector, an outside siren or the control unit. This Tamper switch can be on a standard zone which will cause the alarm to activate if the alarm is set or if the Tamper Switch is on a 24 hour zone to activate immediately. External Sirens and Control Units should be both Tamper Switched to the wall they are attached to as well as having their front covers tampered as well, so if an attempt is made to open or remove them, the alarm will activate immediately.

24 Hour Zones  

24 hour zones are usually used for:

24 hour zones activate 24 hours a day irrespective as to whether the alarm is set or not. Most modern alarms can have as many zones designated as 24 hours zones as required, while older alarm panels often only have one or two 24 hour zones.

The Control Unit

There are two types of Control Units - Hardwired or Wireless; Hardwired alarm systems make up approximately 90% of the domestic market with Wireless accounting for the remainder while the commercial market is 99% Hardwired and 1% Wireless.

Hardwired Control units can use Detection equipment such as PIR’s and Smoke Detectors from all manufacturers, this also applies to Sirens.

Wireless Control panels can ONLY have Detection equipment, Smoke Detectors and Remotes added to them that are specifically made by their manufacturer for that specific model / version, and depending on their configuration may or may not have sirens added.

Wireless Alarm Control units usually come with the keypad as the main control unit, in which case the Controller and Keypad are one and the same.


The Control Unit is the brain of your alarm system. Modern alarm systems are microprocessor based and most have an on board Analogue Dialler attached to their circuit board, this enables them to communicate with a central monitoring station. The Control Unit is either wired directly into a 230 Volt AC mains power connection which is then transformed by the Transformer to 16 volts AC or connected to a 230VAC Supply by a 16V AC Plug pack.

The 16V AC from the Transformer or Plug Pack powers the electronic board. The Electronic circuit board in turn rectifies the 16V AC to 12 volts DC. 99.9% if Alarm Detectors, Keypads and Sirens operate on 12VDC

The Control Unit has a backup battery power supply, for hard wired systems this is usually a 6.5AH OR 7.0 AH Battery and for wireless systems this is usually 1.2AH or 2.4AH. The Battery is trickle charged by the Control Unit and should last approximately 3- 5 years.



The Control Unit’s size is identified by the number of zones it has, Control Units commonly come in 4, 8 or 16 zones and then can be enlarged by the addition of expander boards in multiples of 4, 8 or 16 zones. 4 or 8 zones are sufficient for most home or small business applications. Larger capacity alarm panels can have up to 300 zones for large installations.

One piece of detection equipment should be installed onto one zone. This makes fault finding easy and identifies which zone has activated. The Control Unit zones usually have balanced end of line resistors that can be either 24 hour zones (live all the time) or only live when the alarm is set.

The Alarm Control Unit should be installed in a secure location under the protection of an Passive Infra-Red Detector, usually in a cupboard and should be in a box that has a tamper switch,

Often Control units are installed in the Roof, we do not recommend this practice due to the dust, dirt and temperature variations that occur in the roof, not to mention the increased risk of Siders, cockroaches and rodents. 

Hardwired Alarm systems can have wireless detection equipment added provided a Wireless Receiver is added to the alarm.

Location of the Control Unit     


When installing an alarm the installer should take time to access the best location for the Control Panel, remembering it requires a connection to:

For Hardwired Alarm systems we usually install the Alarm Controller either in a Kitchen Cupboard, a Hallway Cupboard, the Laundry OR in the Roof beside the Manhole, whereas for Wireless Controllers with onboard keypads we install them where power and telephone is available, usually in the Kitchen

 Alarm Warehouse Recommendations

>  That if at all possible you install the Control Panel in an easily assessable location in the Garage, Laundry, or Hall Cupboard, this means the alarm can be easily        serviced without climbing into the roof and a cupboard is less dusty and hot than the roof and not as likely to suffer water OR rodent damage

> Always Tamper the Control Unit

>  Always label cables so it is easy to troubleshoot

>  Always Loom cables

>  Always tie cable with cable ties so it looks tidy

The Keypad


While older alarms were key switch operated modern controllers are usually operated by a Keypad. For all modern alarms the Keypad is an extension of the controller and each model / Version of alarm has its own Keypad.

Modern alarms have the capability to have more than one keypad operate them and can be partially armed (Night armed or Stay armed), and as well, zones can be isolated by the user as required. Access through the keypad is via a PIN number, usually four digits. The keypad can also send Raid / Duress / Medical Alarm / Fire Alarm signals and can activate the alarm instantaneously if a Panic Button is pressed.                                                                                                                           

There are a number of types of keypad including LED, ICON, LCD, choose the keypad from each manufacturer that suits you best       


                  Arrowhead LED                             Arrowhead ICON                          Arrowhead LCD                      

The keypad should be installed in an area protected by a Passive Infra-Red Detector

Hardwired Alarm Control units usually come with one keypad; extra keypads can be added. The number of keypads that can be added to each Alarm Controller is specific to that Controller as is the distance to the furtherest Keypad

Location of the Keypad


 The Keypad is best installed in the center of the home so the clients have easy access to the Keypad from the entry doors and also easy access for night arming, in new homes were you are pre wiring the keypad should go close to the entry door but far enough from the door so that a PIR detector sees the client before they get to the Keypad so that the entry beep will remind them that the alarm is armed.

Alarm Warehouse Recommendations: 

>  In an existing home install the Keypad on one of the outside walls of the cupboard the control panel is located in, don’t try to install it by the front door even if clients want it there as cabling will be difficult if not impossible

>  In a new home that you are pre wiring the Keypad should go close to the entry door, but preferably far enough away so that a detector sees the client before they get to the Keypad so that the entry beep will remind them that the alarm is armed.

>  Don’t use power cables as draw wires as cables of different voltages must have a separation distance of 100mm or you can get electrical interference

>  Install the keypad at a height that can be easily accessed, check with the owner what they require



                         Arrowhead                                           Paradox                                    Paradox Receiver

Most modern alarm systems have the capacity to be armed and disarmed via a remote button carried on your key ring. If your alarm Control Unit does not have Wireless Capability you will have to add a receiver board for the first remote, or detector, thereafter as many remotes or detectors as you wish can be added.

Remotes are matched to Control panels; if you want remotes to be added to your alarm then we need to know the type of alarm panel and version, we can then ascertain if a receiver is available as only some panel versions can operate remotes.

If a receiver is not available we can add a generic type receiver that will fit any panel

Remotes are powered by batteries which have to be replaced regularly, approximately 24 monthly depending on usage. Remote batteries can be purchased from our website or from Home Improvement stores and shops selling small batteries

There are 2 types of remotes; 2 or 4 button Remotes. Remotes have the following functions:

Remotes can be programmed to either flash the outside siren light or squawk the outside siren on setting and unsetting to let the operator know the alarm is set. (1 Siren Chirp and / or Flash for on and 2 Siren Chirps and / or Flashes for off)

Remotes do not replace the keypad but are an extra, which makes operating the alarm easy especially where they are automatic garage door openers.

Remotes are perceived to be a security risk because:

The problems with remotes are:

Alarm Warehouse Recommendations: 

> If adding Remotes then you should always connect the Siren Chirp function to the External Siren or the Client knows if the alarm is set / unset from a vehicle (you will not hear the keypad beeping the exit or entry delay from a Car)

> Remotes should not be used in Commercial installations because of the Security risk

> Keep the user instruction manual so you know which batteries to purchase for your Remote.

> Check the range, you may have to move the Remote Receiver or add a Repeater or Aerial

> If adding Siren Chirp, some alarms will require a specific External Siren to work correctly

Night Arm Stations


                                            Micron                                             Bosch

Night arm stations are just about redundant now as have been replaced by Remotes. Night Arm Stations are normally situated in a bedroom and enable the user to partially arm / disarm the alarm from the bedroom. They also have a panic feature on them. Night arm stations are an item of add on equipment added to the alarm Controller, and only fit the type of controller they were made for. Not all alarm panels / versions can have night arm stations added to them

The location of Night Arm Stations is important as they can be virtually impossible to install beside the client's bed, and if the beds position is moved then the Night Arm Station is in the wrong place. A good idea is to install the night arm by the door inside the bedroom, and install a one way lock on the door of the bedroom side. The bedroom then becomes a safe zone. If you want to add Night arm stations then you will have to ensure that your alarm system is capable of having a Nitearm Station added.

Alarm Warehouse Recommendations: 

> Install the night arm by the door inside the bedroom,

> Use Remotes instead of a Night Arm Station, home invasions and problems can occur at any time

Internal Sirens

Top Hat and Flush Mount are the two most commonly types of Internal Siren

Top Hat Sirens are shaped like a top hat and usually put out 120 decibels, (they fit on the ceiling or wall)


                  Top Hat Internal                                      Flush Mount Internal

Flush Mount Sirens usually put out 105 decibels, they look very neat as they do not protrude from the ceiling but are not as loud as Top Hat Sirens because some of their noise is dissipated into the roof. If you are upgrading an old alarm system, the sirens may have to be changed from speakers to sirens. Speakers require audio to operate, whereas sirens require 12 volts. While some old panels utilised audio to operate, most modern alarms do not have this function.

Flush mount sirens are more difficult to install (require a 54ml hole saw) and leave a 54mm hole in the ceiling if removed

Location of the Internal Siren

Ideally the Internal Siren is installed in an open area close to the center of the home so the noise is easily heard throughout the house. In an existing home the Internal Siren often ends up on the outside wall of the cupboard the Control Panel is located in or on the roof below the Control Panel if the Control panel is in the roof

Alarm Warehouse Recommendations: 

> Install the Internal Siren in the roof of a hallway,

> If using a Flush Mount (requires a 54Mm Hole) measure where you are drilling OR drill from the top to make sure that you are drilling the hole into Gib Board, not te framing 

External Sirens

There are a number of external sirens available:

Polycarbonate External Sirens are the most common sirens used in the security industry are in tamper proofed boxes tamper switched so if their lid is opened or they are removed from their position they will activate. When the alarm activates, the siren activates and a strobe light flashes.

Advantage: Reliability, no electronic board in the outside siren which will activate by itself if it gets wet or corrodes.

Disadvantage: If the siren cable is cut it will not activate as it has no independent back up power source.



If you require Siren Chirp with Remotes some alarms require a specialist Siren to be used.

Steel Satellite Sirens have an electronic board plus a backup battery in them which, if the siren cable is cut will activate.

Advantage: Will activate even if the siren cable is cut (until the battery runs flat) or if the alarm panel loses power.

Disadvantage: Unreliable, if the siren board gets wet or corrodes it will activate by itself and will not turn off.

Uses: High risk sites or where the siren cable is easily accessible from the ground.

There are three types of satellite sirens: Standard as above, Double Skin for High risk commercial sites and Stainless Steel for use where corrosion is a problem i.e. salt water / spray 


External Horn Siren / Horn Speakers are not tampered and are a two wire Horn Siren or Speaker which, if the wires are cut, will not operate. Only usually found in older systems or where the Siren is an additional siren to provide extra noise.


Rural Blasters are a large horn siren that is much louder than a traditional siren. Rural Blasters have to be powered independently from the alarm power supply. They are ideal for use in rural environments and large warehouses. Rural blasters do not replace the need for an external siren, but should be used as an additional siren to the Satellite siren                                                                         


Location of External Sirens

Usually we install the External Siren in the front of the home or business premise upright and in clear view from the street.

Wiring can be difficult so always check where you can get cable to before settling on where it is going to be

 Alarm Warehouse Recommendations: 

>  Check with the client where they want the siren, especially in designer homes clients often want it out of view

>  Don’t install the Siren in a location that you will not be able to reach easily from a fold out ladder in the future

>  If installing Rural Blasters install them out of site as they are not tampered

>  Use the appropriate siren for the circumstances

Hardwired & Wireless Passive Infra-Red Detectors (PIR’s)


95% of the Detection Equipment used by the Security Industry are Passive Infra-red Detectors, commonly referred to as PIR’s. They are reliable, aesthetically attractive and if installed correctly are relatively reliable. PIR’s measure the movement of a heat source against the background ambient temperature of the area they are installed in, and if the difference is great enough will activate. PIR’s emit a series of Infra-Red beams like fingers on a hand and at various height levels. The number of beams, their coverage pattern and range vary for each make and model of detector. Most PIR’s provide a coverage area of 12-15 meters at a 90° angle.

Beams can be masked out of detectors if required so not to cover a fire place, and as well, modern PIR’s have a sensitivity adjustment on them so the PIR will trip on either the first, second or third time the Infra-red beam is broken. PIR’s are powered by 12 volts DC (direct current) from the alarm controller or, if they are a Wireless PIR via a battery, usually 9 volts. Hardwired PIR’s are relatively maintenance free as they have no battery to replace, however with the development in recent years of long life Nickel Batteries some wireless detectors now get up to three years of Battery life.

Because of the PIR’s coverage pattern the most effective coverage is gained by having the likely intruder walk across the coverage area rather than towards the PIR. PIRs have LED’s in them (light emitting diodes) which come on when the PIR is tripped. This LED can be turned off if required. As standard the LED's in PIR's in commercial sites should be disconnected. This stops criminals walk testing the detection area, where as domestic sites we leave them on. The PIR should have a tamper switch on the cover so if the lid is opened the alarm will go off. The screws holding the PIR to the wall and the cable hole should be cemented up so that insects cannot walk over the Infra-Red lens.

As well as standard PIR’s there are PIR’s available that have different detection patterns, different ranges, some have dual beams, some are active infrared and some combine PIR and microwave technology. Curtain lens PIR’s are also available. They only have beams at one height horizontally or at one position vertically. Long range PIRs are available, however these are expensive (up to 10 times the purchase prices of normal PIRs). Sometimes it is better to add extra detectors which will be more cost effective and give much better coverage.

Adding a Wireless Receiver or using a wireless enabled alarm allows wireless detectors to be added to an existing Hardwired Alarm.

Wiring Diagrams

The following are commonly used wiring configurations

Single Normally Closed Sensor with Single End of Line Resistor


 Multiple Normally Closed Sensors in series with Single End of Line Resistor


Single Normally Closed Powered Sensor with Single End of Line Resistor with Tamper Wired on Same Zone (Note: It is easier to wire the resistor in place of the bridge between NC and Tamper)


Types of Detectors

Alarm Warehouse Recommendations: 

>  Install the Detectors in the top corners of rooms, making sure no cable is visible

>  In most cases install Detectors in the corner of the room nearest the entry from the Hallway  

>  Try not to install looking into the setting sun in large rooms such as lounges to avoid activations caused by heat spots

>  Don’t install Detectors beside Air Conditioners OR looking Directly at Air Conditioners to avoid false alarms caused by air movement

>  Don’t install Pet Detectors looking at areas where the Pet is likely to jump OR run down stairs to avoid false alarms caused by the Pet moving downwards through the detectors coverage pattern

>  Don’t install Detectors looking at Fire Places OR Incinerators to avoid false alarms caused by air movement

>  When installing the Detectors loop the Tamper Circuit on the Detector into the Alarm Relay loop

>  Install the detector within the height recommendations if possible, on high ceilings you may have to point the Detector down  

>  If using Wireless install 1 Wireless detector per zone

Smoke Detectors

All Smoke Detectors now used are the photoelectric type. There are very specific Fire regulations regarding the location of smoke detectors, smoke detectors should never be installed within 100mm of a corner of a room as in a fire this becomes oxygen trap                                                                                      


Alarm Warehouse Recommendations

>  Install the Detectors in the Hallway area (By law every home requires a working smoke detector within 3 meters of each bedroom door and on each level)

>  Always install the Detector on a 24 hour zone

>  Don’t install the Detector where Steam from opening the bathroom door  can activate it

>  Don’t install Smoke Detectors right in the corner beside the walls and roof so as to avoid Oxygen traps 

>  Location priority 1: Hallway(s) Keep as far from the bathroom door as possible to avoid steam from the bathroom setting it off 

>  Location priority 2: Lounge, keep as far from fires and stoves as possible

>  Location priority 3: Attached garages


Remote Buildings


Hardwired systems require a cable to be connected from the Control Unit to the each detector, keypad and sounder. In Buildings not attached to the building the Alarm Control panel is located in the choices are:

Alarm Warehouse Recommendations

>  Check distances carefully if using Wireless Options as there are range limitations, the range on equipment brochures lists range taken in open air in a dry flat environment with no signal suppression

>  If the Remote Building is Tin or Metal then range can be greatly suppressed and you may need to add aerials or add a repeater or move the receiver closer to the Remote Building                                                                      

Hardwired & Wireless Panic Buttons


There are two types of Panic Buttons

Alarm Warehouse Recommendations

>  Always test the range of Wireless Panic buttons

>  Check if the client wants them to be audible or silent

>  Make sure the client can turn the off

>  For Fixed Panic Buttons do not use switches that have an on / off function, they should be spring loaded so activate every time they are pressed and cannot be turned off accidently     

Ultrasonic Detectors

Ultrasonic detectors detect the disruption of sound waves and should be used in high risk sites. They do not transmit through glass or walls and are prone to false alarms. They were popular originally but are hardly ever used these days as they are unreliable


Alarm Warehouse Recommendations

>  Do not use them

>  If you do test them properly


Microwave Detectors


Microwave detectors detect movement only. These detectors usually combine both PIR and microwave into one sensor. Their pattern of coverage is of an oblong type up to 15 meters in distance. Microwave detectors must have their beams terminated into the ground as they operate through walls and windows. They will detect for example water running down a drainpipe inside a wall. For this reason it is crucial that microwaves are set up correctly. Although false alarms are obviously a problem for the aforementioned reasons, these detectors do offer the highest degree of protection as they cannot be shielded in any way. If something moves the detector activates.


Alarm Warehouse Recommendations

>  If installing 2 Microwave detectors within the one area you must use different frequencies

>  Microwave detectors should be used in high-risk situations and usually in combination with standard PIRs.

>  The detector must be sent to activate when either the PIR or the microwave are tripped within a set time span.

>  They are designed for use in high risk sites where intruders are camouflaging their body heat.

>  When installing remember that the Microwave detection pattern is in an oval shape and includes 10% of the range behind the detector

>  Microwave detectors pick up all movement within their detection area including running water in water pipes so siting of the detector is critical

Glass Break Sensors

Glass break sensors detect the noise of breaking glass and are usually set up inside a shop facing glass windows/doors. As a rule of thumb one glass break sensor will protect 5-6 meters of glass. Glass break detectors DO NOT operate with laminated or toughened glass. Shock Sensors must be used in this instance. They only operate to a maximum glass thickness of 4ml. Most Glass Break sensors have a sensitivity adjustment and some models have a pulse count facility. These types can be an advantage as they won't activate if people bang the windows with their keys or the like, however they may not operate if only a small amount of glass is broken.


                                               Micron                                                      Paradox                                                       

Alarm Warehouse Recommendations

>  Glass break sensors should be on an instant zone, so the alarm is sounding while the burglar is still outside the premises.

>  While Glass break sensors are used in commercial installations and can be effective, shops should not have valuable items on display close to windows as glass can be covertly cut out which may not create enough noise to activate the glass break sensor.

>  Some types of laminated Glass will not activate Glass Break Sensors

Point to Point Beams

Point to Point beams can be used both inside and outside, they operate by transmitting a beam of light between 2 fixed points, when the beam is broken the detector activates. The most reliable Point to Point beams have two beams or 4 Beams approximately 100mm apart, all of which must be broken to activate. That way a leaf or bird will not cause false alarms. The Point to Point beam required depends on if they are inside or outside and the length of beam required.

12v DC must be supplied to each end of the Point to Point but only the transmitter requires a closed loop wired back to a zone on the alarm panel. Point to Point beams give ideal protection for car yards, driveways, farmyards etc. Installed correctly they are reliable.



Alarm Warehouse Recommendations

>  Only install Beams that require both Beams to be broken before they activate

>  Always install beams with a distance margin of error

Shock Sensors and Vibration Sensors



A variety of shock sensors are available. These operate if a sharp jolt is felt. They are usually connected to an alarm zone by a 4 core cable, though some shock/vibration detectors also require 12v DC to operate. Uses for shock sensors and vibration sensors are on safes, or in or on walls in high-risk sites. Shock and vibration sensors should be connected to instant zones on the alarm.

Alarm Warehouse Recommendations

>  Only install sensors that are suitable for what you require

>  Read the brochure for the detection pattern

>  Always install more rather than less sensors, especially on walls

Industrial Switches



There are many different Industrial Switches available. Common types and applications:

Alarm Warehouse Recommendations

>  Contact us for advice

>  Only install sensors that are suitable for what you require

>  Always read the instructions to ensure they are suitable

>  Thoroughly test any detector that you have installed

Heat Sensors

Heat sensors come in two types; 57° and 75° sensors.

There are specific fire regulations regarding the location and distance between Heat Detectors and the type of cable required. The Cable must be 1.00mm Fire Cable. Heat sensors must be sited no more than two meters from any wall and three meters apart. Heat sensors are wired up in series.


Alarm Warehouse Recommendations

> Only install sensors that are suitable for what you require

> Always read the instructions to ensure they are suitable

>  Use the correct cable

>  Heat sensors are not resettable and have to be replaced once they activate

Door Switches

Door Switches can be hardwired or wireless and commonly come in 3 types, Flush Mount, Surface Mount and Roller Door.

In modern alarm installations the only type of door switch commonly used are Roller Door Switches, they are wired into a standard zone and activate as a normal zone.


Alarm Warehouse Recommendations

>  Only install sensors that are suitable for what you require

>  Test their tolerance level to ensure they don’t false Alarm

>  Always read the instructions to ensure they are suitable

Servicing Alarm Systems


All Alarm systems need regular servicing, the Insurance recommends 6 Monthly for commercial sites and 12 monthly for Domestic alarms. In reality many people service the alarm every 2-3 years. Servicing will decrease false alarms because detectors are checked for spiders, all terminal connectors are checked, the Panel Battery is checked (usually they last about 5 years), keypad codes should be changed, sensors are cleaned and the sirens are checked including checking for dry joints in the External siren

Alarm Warehouse Recommendations

>  Always check the alarm Keypad for fault conditions

>  Replace the Battery if it shows sign of corrosion , cracking OR it rattles when it is shook

>  Test the Battery under load if you have a load tester

>  Do not open the PIR sensors as often the plastic lid will have become brittle over time

>  Check All sensors operate by walk testing them

>  Check that sensors have not had their field of view partially or fully blocked





For use inside to hide cables



For use outside to protect cables and hide cables from sight