Purpose

Security intercom systems are used to provide voice communications between two or more locations for security purposes. Security intercom systems are frequently used between a locked building entrance door and a constantly attended location in the building, such as a manned security control room. In this application, the security intercom system gives visitors a means to contact someone in the building when they arrive at the entrance door. Other common locations where security intercom systems are used in commercial buildings includes loading dock doors and at vehicle gates that provide entrance to the property. In residential applications, security intercom systems are commonly used between the main entrance door and a location within the interior of the home.

Simple Intercom System with One Sub-Station

A simple intercom system consists of one “Master Station” and one “Sub-Station”. The Master Station is typically located at the point inside the building where communications is to be received. The Sub-Station is typically located at the point where the communication is to be originated. For example, in an office building, it may be desirable to keep the front entrance door locked, and to provide a security intercom system to allow communications between the outside of the entrance door and the receptionist’s desk in the lobby. In this situation, the intercom Master Station would be installed at the receptionist’s desk, and the Sub-Station would be installed on the wall outside of the entrance door.

The Master Station provides control of the intercom system and typically includes a station selector switch, talk button, speaker, amplifier and volume control. The Sub-Station typically includes just a speaker and call button. When the visitor arrives, he or she presses the call button on the Sub-Station. This causes the Master Station to ring. To accept the call, the receptionist presses the station selector switch. When this button is pressed, the receptionist can instanlly to listen to sounds at the Sub-Station. To talk to the visitor, the receptionist presses the talk button. When finished speaking, the receptionist releases the talk button to listen to the reply from the visitor. This goes back and forth for as long as the conversation continues, with the receptionist pressing the talk button when she wishes to speak, and releasing the talk button when she wishes to listen. At the conclusion of the conversation, the receptionist presses the station selector switch again to terminate the connection.

Simple Intercom System with Multiple Sub-Stations

In many facilities, there may be a need to communicate with more than location. For example, in the office building described above, there may be a need for the receptionist to communicate with the employee entrance door and the loading dock door in addition to the front entrance door. To meet this need, Master Stations are available that can accommodate multiple Sub-Stations. Models that have a capacity of three, five, or ten Sub-Stations are common.

Master Stations that work with multiple Sub-Stations have a station selector switch for each station. Above each switch is an indicator light as well as a label that identifies the Sub-Station (“Front Door”, “Back Door”, etc.) When a visitor presses the call button on a Sub-Station, it causes the Master Station to ring, and for the indicator light above the appropriate station selector switch to illuminate. The receptionist can then press the station selector switch for the station that is calling and begin the conversation using the talk button as described above.

Simple Intercom System with Multiple Master Stations

Sometimes, there is a need to receive intercom calls at more than one location in a building. For example, you may wish for the receptionist to receive calls during normal business hours, but after-hours, you may wish for calls to be received at the security control room. To meet this need, it is possible to provide multiple Master Stations, each capable of communicating with one or more Sub-Stations. Communications between each of the Master Stations can also occur if this is needed (for example, receptionist could use intercom to talk with security control room and vice versa).

In most cases, the system is designed so that calls from Sub-Stations are received at all Master Stations. The first Master Station that answers the call handles it and all other Master Stations ignore it. Typically, when one Master Station is in use, other Master Stations cannot be used. The system provides a “busy” indicator light at each Master Station to indicate when the system is in use by others.

Simplex or Duplex Communications

The simple intercom system described above uses what is known as “simplex” communications. “Simplex” communications means that communications can occur in only one direction at a time. In the examples above, the receptionist uses the talk button on the master station to control the flow of communications. The receptionist can either talk or listen, but not do both at the same time.

More sophisticated intercom systems are available that use what is known as “duplex” communications. “Duplex” communications means that communications can occur in both directions at the same time. When using an intercom system that has duplex communications, there is no need for a talk button; once a connection is established between a Master Station and a Sub-Station, a two-way conversation can occur without either party having to operate any type of control. This is a much more natural way to communicate and avoids the gaps in a conversation that can occur when the talk button is pressed too soon or too late.

As a general rule, most simple, inexpensive intercom systems use simplex communications, while more expensive intercom systems use duplex communications.

Handset or Hands-Free Intercoms

Intercom stations are typically available in two versions, a “handset” version, and a “hands-free” version.

Handset intercom stations use a corded handset similar to that found on a telephone. The advantage of handset intercom stations is that they work well in noisy environments and that they provide some degree of privacy. The disadvantage of corded intercom stations is that they are less convenient to use and that they are more prone to vandalism and routine wear and tear.

Hands-free intercom stations use a speaker/microphone that is built into the unit. Hand-free intercom stations are more convenient use and less prone to damage, but sometimes can be difficult to use in noisy environments. Hands-free intercoms stations also offer little privacy.

Some intercom stations come with a handset but are also capable of being used hands-free. These stations have a speaker/microphone in addition to a handset and usually work as a hands-free unit unless the handset is picked up.

Wired or Wireless Intercoms

Most intercom systems have traditionally been the “wired” type that require low-voltage wiring be installed between each of the Master Stations and Sub-Stations. On larger or more complicated systems, this wiring can become quite extensive and may be costly to install. However, once installed, wired intercom systems tend to be very reliable and require very little maintenance. Because of this, wired intercom systems have long been the preferred choice of most commercial and industrial users.

Intercom systems are also available that allow “wireless” communications between Master Stations and Sub-Stations. These systems typically use radio signals to provide the communications path between stations and don’t require any type of wiring. The advantage of these systems is that they are quick and convenient to install. The disadvantage of these systems is that they don’t work well in all settings, and may not work at all in buildings that contain large quantities of concrete and steel or when there are long distances between the stations. Most wireless intercom systems also lack the features needed for the larger commercial user and are considered to be less reliable over time than a wired system. Because of this, wireless intercom systems are usually best suited for use in private homes and at smaller commercial businesses.

IP Network Connected Intercoms

A recent development in intercom systems is IP network connected intercom stations. These stations are capable of being connected directly to an organization’s existing data network. This usually means that the intercom station can be plugged into a nearby network outlet or unused port on a nearby network switch. This can greatly reduce the costs of installing wiring and offers great flexibility in the way that intercom systems can be installed and modified. IP connected intercom stations are well-suited for use in large campus environments, particularly when the campus includes buildings that are off-site.

Door Release Buttons

When an intercom system is used to communicate with a door, it is often desirable to have the ability to remotely unlock that door. For example, if an intercom system is used between a receptionist’s desk and a locked entrance door, it is common to provide the ability to remotely unlock the door for authorized visitors. Many simple intercom systems incorporate a door release button into the intercom Master Station specifically for this purpose. This button is wired to electrified locking hardware (such as an electric strike) on the door, and when the button is pressed, the door unlocks.

When multiple doors and multiple Sub-Stations are used, remotely unlocking doors becomes a little trickier. Some Master Stations can use accessory relays that allow the door release button to work in unison with the station selector switch. This allows the door release button to release the door that the station is currently in communication with.

Video Intercom Systems

Intercom systems are available that incorporate video surveillance features. Video intercom Sub-Stations are similar to regular Sub-Stations except that they also include a small built-in video camera that provides a direct view of the person operating the station. Most cameras offer a fixed viewing angle; some cameras can be moved up and down and right and left by the person receiving the call. Video intercom Master Stations are similar to regular Master Stations except that they also contain a small video monitor. This monitor is used to view the image produced by the camera in the video intercom Sub-Station.

The advantage of video intercom systems is that they allow the person receiving a call to verify the identity of the person calling. This can be particularly useful in door control applications where it is desirable to confirm which person is at the door before pressing the door release button.

While most video intercom systems provide a good view of a person standing directly in front of the intercom Sub-Station, they generally don’t provide a wide-angle view of the overall doorway itself. In addition, cameras in video intercom systems tend to be only of moderate quality and generally not suitable for use with video recording systems. For these reasons, most organizations who are serious about security don’t consider the cameras built into video intercom systems to be a substitute for regular surveillance cameras and generally install both at entrance doors.

Exchange Intercom Systems

It is possible to mix and match simple intercom Master Stations and Sub-Stations to create a relative large system. However, when a facility becomes very large and has  many Sub-Stations and Master Stations, the system can become complex and unwieldy. This can occur in campus settings where there are many buildings and many doors.

To meet the needs of larger systems, “exchange” intercom systems were developed. These systems get their name because a central controller, called an “exchange”, is used to manage intercom system traffic. Rather than being connected directly together, Master Stations and Sub-Stations are connected to the exchange. Most exchanges allow the use of both wired intercom stations and IP network connected stations. When a call is placed, it first goes to the exchange, where it is them routed to the appropriate station.

Master Stations used with exchange intercom systems often are microprocessor based and operate using a menu driven system. This also a powerful set of features to be packed into a relatively compact station. The benefits of using an exchange intercom system are many and include:

• Can be expanded to a practically unlimited number of intercom stations
• Can carry out multiple conversations between stations at the same time.
• Can route calls to specific stations based on time of day.
• Can forward calls if station is busy or if call goes unanswered.
• Can operate auxilary relays to unlock doors, turn on lights, etc.
• Can use plain text to identify stations within operating menus.
• Can interface with telephone and two-way radio systems.
• Can interface with security management systems.
• Have ability to be programmed and controlled using a computer.

As might be expected, exchange intercom systems are considerably more expensive than simple intercom systems and are most cost effective when used at larger facilities. The cost of an exchange intercom systen cannot generally be justified at a smaller facility.

“Exchange-Less” Intercom Systems

A new breed of system, called an “exchange-less” intercom system has recently been introduced. These systems use IP connected stations that have built-in processors and memory that allow them to provide many of the features and benefits of a exchange system, without requiring the use of an exchange itself. These systems can offer the smaller user a very capable system at a fraction of the cost of an exchange system. While still more expensive today than simple intercom systems, we see exchange-less IP network connected systems as the wave of the future.

Using Security Intercom Systems to Enhance Your Security Program

In addition to being used for basic communications purposes, security intercom systems can be used to enhance your facility’s overall security program. Security intercom systems can be particularly powerful when integrated with other systems such as security management systems and video surveillance systems.

For example, with a fully integrated system, when a “door-forced-open” or “door propped” alarm occurs at at access controlled door, the Sub-Station at that door can automatically  be connected to an intercom Master Station at the security control room. In addition, the camera at that door can automatically be displayed on a video monitor. This allows the security officer to both listen to and see what is going on at the door and possibly give a verbal warning to those who may be violating a security procedure (“Hey, you, please don’t prop the door open…”).

Security intercom systems, when combined with appropriate signage, can also be used for customer service functions such as providing directions to visitors, allowing employees to request a security escort to their cars, and notifying security of safety violations.

If you have questions regarding security intercom systems, or need help in designing a security intercom system for your facility, please Contact Us.

Purpose

The purpose of a panic alarm is to allow a person under duress to quickly and silently call for help in the event of an emergency. Panic alarms are also called “duress alarms”, “hold-up alarms”, or “panic buttons”.

Panic alarms are used when it may be unsafe or uncomfortable to call for help in other ways. For example, if a belligerent person is standing in your lobby, it may be unwise to further escalate the situation by picking up a phone to call for assistance. A panic alarm can provide a quick and convenient way to summon help without drawing attention.

Silva Consultants feels that almost every business can benefit from the use of panic alarms. Places where panic alarms may be particularly beneficial include:

• Receptionist’s desks in building lobbies.
• Security stations and checkpoints.
• Shipping/receiving areas.
• Customer service counters.
• Check-out counters and cashier’s stations.
• Rooms where cash or other valuables are received, processed, or stored.
• Interview rooms in Human Resources department.
• Executive office suites.
• Places where confrontations with the public are likely to occur.

Components of a Panic Alarm System

Panic alarms consist of two basic components:

Panic Button

The panic button is the device that the person activates when he or she needs help. There are many styles of panic buttons available. These can have a single pushbutton, two pushbuttons that must be pressed simultaneously, devices that must be squeezed, and devices that are activated by a foot or knee. There are also devices that can be covertly activated when cash or a product is removed at the request of a robber. Most panic buttons are specifically designed to resist accidental activation.

Panic buttons are normally installed in a location where they can easily be reached, yet out of view of the casual observer. In many cases, panic buttons are installed on the underside of a desk or countertop.

Panic buttons can be the wired type or wireless type. Wired panic buttons are connected using cabling. Wired panic buttons are very reliable, but it can sometimes be difficult and costly to get cable to each panic button location.

Wireless panic buttons use a short-range radio transmitter, similar to that used with a garage door opener. Wireless panic buttons are easy to install and can be placed just about anywhere.  Wireless panic buttons can also be carried around on the premises by employees if desired. Wireless panic buttons require batteries and need to be tested frequently to assure that they are operating properly.

Communications System

The communications system is the method that is used to summon help when a panic button is pressed. The type of communications system used depends largely on the resources available at the facility where the panic alarm is being installed and the level of security threat.

Types of communications systems used can include:

Communications to an off-site alarm monitoring center:

This method would typically be used at facilities that do not have an on-site security staff, such as at a small business. The panic buttons would be connected to an alarm control panel which sends a signal to the monitoring center when a panic button is pressed. The alarm monitoring center would then call the police or other appropriate people to respond to the site.

Communications to security control center:

Most large companies have some type of centralized security monitoring and control center, either on-site, or at a central location somewhere within their organization. When this type of resource exists, panic buttons are typically monitored at the control center. Most often, panic buttons are connected to the organization’s access control and security management system, which transmits the alarm to the control center.

When a panic button is pressed, it sounds an alarm in the security control center. The center would then dispatch local security officers and/or the police to respond to the site.

Communications to non-security personnel:

Some organizations that do not have on-site security choose to notify non-security personnel when a panic button is pressed. Often, the organization will form a “response team” consisting of employees from multiple departments (Facilities, HR, etc.) and ask that these employees respond when a panic button is pressed.

There are various systems that can be used to notify the response team when a panic button has been pressed. These include can include overhead paging systems and devices that send voice messages, text messages, or email messages directly to smartphones.

Tips for Successfully Using Panic Alarms

1. Panic alarms are worthless unless people know how to use them. Provide frequent training and make employees practice using panic buttons, particularly at positions where there is high employee turnover.
2. When possible, provide a video surveillance camera that views each area where a panic button is installed. The panic alarm system should be interfaced to the video surveillance system to provide real-time recording when a panic button has been pressed. At facilities that have a security control center, the video surveillance system should automatically display the appropriate cameras at the control center whenever a panic button has been activated. This allows the center to assess the situation in order to send the proper response.
3. Facilities that use a response team to respond to panic alarms should have some method to assess the situation before personnel enter the scene. Cameras that view panic button locations should be remotely viewable by response team members. This can be done using a computer on the network that has video viewing software, or by providing one or more dedicated video monitors.
4. In some locations, different types of responses may be needed to handle different types of situations. For example, a drunk person in the lobby poses a different threat than an armed robber, yet employees may wish to have a method for discretely summoning help in either case. To handle this, it is possible to install what we call a “two-state” panic button. This button can be programmed so that two types of signals can be sent, one for true emergencies, and one for when help is needed but the situation doesn’t require an emergency response.

Intrusion Alarm System Components

The typical intrusion alarm system consists of the following basic components:

Detection Devices

Detection devices are the components used to detect the entry of an intruder into the building. There are dozens of different types of detection devices, each which use a different method of detecting the presence of an intruder. The most commonly used types of detection devices at commercial facilities are:

Contact Switches

Contact switches are installed on doors and windows to detect when the door or window has been opened. Contact switches are most commonly installed on doors and opening windows at the exterior of the building, but may also be installed on interior doors.

There are a wide variety of different types of contact switches available for installation on wood and metal doors, windows, gates, hatches, and other types of openings.

Motion Detectors

Motion detectors are used to detect the presence or movement of people within the building. Motion detectors are most commonly installed in hallways, corridors, and within rooms that contain a high concentration of valuables.

There are several different types of motion detectors available. The most common type of motion detector in use today is the “passive infrared” (PIR) detector. The PIR detector detects the body heat of a person as he passes within the viewing area of the detector.

Glass Breakage Detectors

Glass breakage detectors, as their name implies, are used to detect the breakage of glass. Glass breakage detectors are normally installed near accessible glass windows and doors at the exterior of the building.

Signaling Devices

Signaling devices are the devices that the intrusion alarm system activates when intrusion is detected. Signaling devices serve three purposes:

• Notify the intruder that he has been detected, hopefully causing the intruder to flee from the premises, or at least causing the intruder to spend less time in the building.
• Notify neighboring residents and passersby that the intrusion alarm has been activated.
• Notify any employees that may be in the building that the intrusion alarm has been activated.

There are both audible and visual types of signaling devices. Audible signaling devices include bells, electronic sirens, and voice announcement systems which broadcast alarm messages using a recorded human voice. Visual signaling devices include revolving lights, blinking lights, and electronic strobe lights.

Signaling devices are normally installed on both the interior and exterior of the building.

Arming Stations

Arming stations are the devices used to “arm” (turn-on) and “disarm” (turn-off) the intrusion alarm system.

The two most common types of arming stations are the key switch arming station and the keypad arming station.

The key switch arming station uses a special keyed switch to arm and disarm the intrusion alarm system. In order to use the key switch arming station, the user must have a special key.

The keypad arming station uses a digital numeric keypad, similar to that on a touch-tone telephone, to arm and disarm the intrusion alarm system. In order to use the keypad arming station, the user must know the correct code.

In addition to simply allowing the user to arm and disarm the system, the keypad type of arming station can also provide the user with the ability to perform certain advanced functions which the keyswitch arming station cannot. These functions include the ability to arm only a certain portion of the system while leaving other parts disarmed; the ability to perform system diagnostic and maintenance functions; and many other advanced functions.

Both the key switch arming station and the keypad arming station normally provide intrusion alarm system “status indicators”. Status indicators are used to give the user visual information concerning the status of the intrusion alarm system.

The key switch arming station normally uses simple indicator lights to display the status of the system. Usually, a green light on the arming station is used to tell the user that all doors have been closed and that the system is ready to arm. A red light on the arming station is normally used to tell the user whether or not the system is armed or disarmed.

The keypad type of arming station can also use indicator lights, but more commonly, the keypad type of arming station provides an “alphanumeric display” instead of indicator lights. The alphanumeric display uses letters and numbers to display system status information using plain English messages.

The alphanumeric display provides a much greater amount of information to the user than simple indicator lights do. In the event that a door in the building has been left open, the alphanumeric display can tell the user exactly which door has been left open. Alphanumeric displays can also indicate system troubles, alarm activity, and many other conditions.

Arming stations are the primary device that the average user uses to interact with the building’s intrusion alarm system. Arming stations are usually installed inside the building near the doors that are used by employees to leave and enter the building. Arming stations may also be installed on the intrusion alarm system control panel.

Control Equipment

Intrusion alarm “control panels” are the heart of the intrusion alarm system. The intrusion alarm control panel is used to process all system operations and activity. All detection devices, signaling devices, and arming stations directly or indirectly connect to the control panel.

Most modern control panels are actually a specialized form of “computer” which include a microprocessor, computer memory, and data communications modems. These control panels are fully programmable to allow the operating characteristics of the intrusion alarm system to be custom-tailored to meet the needs of the building in which it is installed.

Because the average user of the intrusion alarm system usually never needs to interact with the control panel, these panels are normally installed in a secure closet or equipment room.

Alarm Transmission Equipment

Alarm transmission equipment is used by the intrusion alarm system to communicate alarm events and system activity to an off-site location, such as an alarm monitoring central station.

The purpose of the alarm transmission equipment is to notify the police and building security when the intrusion alarm system has been activated. The alarm transmission equipment can also be connected to the building fire alarm system, and can summon the fire department in the event that the fire alarm has been activated. In addition, the alarm transmission equipment can be used to send reports of system troubles and routine system activity, such as “openings” (disarming of the system) and “closings” (arming of the system).

There are several types of alarm transmission systems. The most common type in use today is the “digital communicator”. The digital communicator uses regular telephone lines to communicate alarm messages to the central station. By using regular telephone lines, the digital communicator eliminates the need to lease special data lines between the building and the central station.

Other types of alarm transmission systems include “multiplex”, “derived channel”, “long-range radio”, and “cellular”. These types of systems provide a greater level of security than digital communicators do, but require that special data lines and/or special monitoring services be provided at an extra monthly cost.

Digital communicators are commonly built-in to most modern intrusion alarm control panels, and only need to be programmed to become operational.

Other types of alarm transmission systems, such as long-range radio or cellular, usually require that a separate piece of equipment be installed and connected to the control panel.

Intrusion Alarm Zoning

An intrusion alarm system in a building can include a large number of different contact switches, motion detectors, glass breakage detectors, and other types of detection devices. A large commercial building such as a warehouse may have detection devices numbering in the hundreds.

To better manage a large number of detection devices, most intrusion alarm systems provide some method of grouping detection devices together. The technique of grouping detection devices together is known as “zoning”. Using the zoning concept, multiple detection devices are combined together into single entities known as intrusion alarm “zones”.

Zones are normally created to divide the intrusion alarm system up into various areas that correspond logically with the physical layout of the  building.

To better explain this concept, let’s say that a building was constructed with four separate wings: North Wing, South Wing, East Wing, and West Wing.

When designing an intrusion alarm system for this building, it would be natural to create intrusion alarm zones that corresponded with each of these wings. Using this example, four intrusion alarm zones would be created: one for the North Wing, one for the South Wing, one for the East Wing, and one for the West Wing.

All contact switches, motion detectors, and other detection devices installed within each wing would be connected to the zone corresponding to that wing.

Zoning of the system provides the ability to monitor the system on a zone-by-zone basis. When the intrusion alarm system is activated, it will report the zone in which the detection device is located that caused the alarm. For example, when an intruder opens a door in the North Wing of the building, the system will communicate to the alarm monitoring central station that the North Wing zone has been activated. This allows the police and building security to respond to the area where the intrusion has occurred rather than requiring them to search the entire building for the point of entry.

Zoning of the system can provide the ability to arm and disarm the system on a zone-by-zone basis as well. For example, if an employee was coming to the building on Saturday, and only needed access to the West Wing, she could disarm the intrusion alarm system only for the West Wing zone, leaving the intrusion alarm zones for the other three wings armed.

Most intrusion alarms systems allow the user to arm and disarm each zone independently; as well as allowing groups of zones to be armed and disarmed at the same time.

Zoning also provides the ability to locate system troubles on a zone-by-zone basis. For example, if wiring for the intrusion alarm system was cut, the zoning feature would allow the service person to quickly identify the wing where the trouble was located.

In our example, we used only four zones for an entire building. In most actual systems, a larger number of zones would be provided. Most of today’s intrusion alarm systems have at least eight zones; and it is not uncommon for a large intrusion alarm system to have 24, 32, 64 or more zones.

In general, the more zones the intrusion alarm system provides, and the fewer the detection devices per zone, the better the ability to control and monitor the system.

Individual Point Annunciation

A fairly recent development in intrusion alarm systems is a concept known as “individual point annunciation”. Individual point annunciation is similar to zoning, except that every single detection device is connected as an individual, unique “point” that reports to the system independently.

Individual point annunciation takes the benefits of zoning to the extreme, and provides information on not only what area of the building the intrusion has occurred, but indicates specifically what device caused the alarm. The police and building security are ability to respond to the exact door or other point of entry where the intruder has entered. Individual point annunciation can also provide the ability to “track” the intruder as he travels throughout the building.

Individual point annunciation greatly reduces false alarms and service costs because the service person can go directly to the specific device that caused the problem rather than having to check every device connected to a zone.

Intrusion alarm systems which provide individual point annunciation provide the ability to group one or more points into logical entities known as alarm “areas”, each of which can be armed and disarmed separately.

(In a system with individual point annunciation, alarm “areas” are roughly equivalent to the “zones” of a simpler zoned system in terms of the way that they are armed and disarmed.)

Intrusion Alarm Design Concepts

There is a great deal of flexibility in the way an intrusion alarm system can be designed for a building. The designer has a great deal of latitude in selecting the quantity and type of equipment that will be used, and in determining where this equipment will be located.

Depending on the owner’s security requirements and budget, the designer may choose to design a simple, “bare bones” system, or may choose to design a deluxe, “high-security” system. The primary difference between a simple intrusion alarm system and a more elaborate one is the number and type of detection devices used.

For example, in a low-cost “bare-bones” system, the designer might choose to install detection devices only at a few points in the building where he feels that an intruder would be most likely to enter. An example of this type of system would be a building where contact switches were installed only on the entrance doors to the building.

In a “high security” system, the designer considers every possible way in which an intruder could enter the building, and places detection devices in such a manner that the intruder is quickly detected in every case. An example of this type of system is the building where contact switches are installed on every door, glass breakage detectors are placed near every window, and motion detectors are provided in every room.

In the real world, most intrusion alarm systems are designed to fall somewhere in between these two extremes. Most systems provide more protection than the basic “bare-bones” system with contact switches only, but not the comprehensive protection provided by the “high-security” system with detection devices in every room.

Exactly how many detection devices should be provided in any given building, what type of detection devices should be used, and where these detection devices should be placed is the subject of great debate among intrusion alarm system designers.

While each different system designer has his or her own idea of what the best arrangement of detection devices is, there are four basic “design concepts” which are commonly used:

Perimeter Protection Concept

The “perimeter protection” concept provides detection at the exterior or “perimeter” of the building. The goal of perimeter protection is to detect the intruder at the point of entry.

Complete perimeter protection usually requires that contact switches be installed on every perimeter door and opening window, and that glass breakage detectors be installed near every glass door and window on the exterior of the building.

Interior Protection Concept

The “interior protection” concept provides detection within the interior of the building. The goal of interior protection is to detect the intruder once he has gained entry into the inside of the building.

Complete interior protection requires that motion detectors be installed in every room and corridor of the building. Interior protection can also be achieved by installing contact switches on the interior doors of the building.

Combined Protection Concept

The “combined protection” concept fully combines the detection capabilities of both the perimeter detection concept and the interior protection concept.

The combined protection concept utilizes perimeter detection devices, such as contact switches on exterior doors, as well as interior protection devices, such as motion detectors installed in rooms and corridors.

The combined protection concept provides the benefits of both perimeter protection and interior protection, and is commonly used in “high security” applications, such as at a jewelry store or at warehouses that contain high-value merchandise.

Hybrid Protection Concept

The “hybrid protection” concept utilizes some portions of the perimeter protection concept, and some portions of the interior protection concept.

The goal of the hybrid concept is to take advantage of the benefits of both perimeter and interior protection, while at the same time keeping the cost of the system below the cost of the fully “combined” system described above.

The typical hybrid system uses partial perimeter detection and partial interior protection. An example of a system designed using the hybrid concept would be a building where contact switches were installed on perimeter doors, and motion detectors were installed in hallways and corridors. This system does not provide complete perimeter protection (there are no glass breakage detectors), and does not provide complete interior protection (motion detectors are not provided in every room), yet the combination of detection devices together provides a reasonable level of protection for the building.

There is a great deal of flexibility in the way a hybrid system can be designed. The designer may choose to provide full perimeter protection in some portions of the building, and choose to have only partial perimeter protection in other parts of the building. The same is true with interior protection; complete interior protection can be provided in some areas, while partial or no interior protection can be provided in other areas.

The following are some of the advantages and disadvantages of each of the four security system design concepts:

Perimeter Protection Concept

Interior Protection Concept

Combined Protection Concept

Hybrid Protection Concept

Most residential and commercial alarm systems use “digital communicators” to transmit the alarm signal to the alarm monitoring central station. While very cost effective, digital communicators have one weakness: they depend on the telephone line to transmit their message. If the telephone line is cut or otherwise disabled, the alarm system cannot transmit its signal.

Many criminals are aware of this weakness and will cut the telephone line prior to committing a burglary or other crime. If the alarm system is totally dependent on telephone lines, the system is rendered useless if the telephone lines are cut. In most cases, neither the facility owner nor the central station is aware that the telephone lines have been disabled until after the crime has been committed.

There are several options that the facility owner should consider to overcome the weakness of telephone lines:

Protect the Telephone Line Where It Enters Your Building

In many cases, telephone cables are installed overhead between the telephone pole and your building. Most of the time, exposed telephone cable will be routed down the side of the building and will terminate at a little box (called a “protector”) which is installed two or three feet above the ground. If your telephone cables are installed this way, they are easily accessible to an intruder. Two suggestions:

• Protect the telephone cabling on the outside of the building by installing it in metal conduit.
• If possible, try to have the protector installed on the inside rather than the outside of the building. If this is not possible, install the protector in a locking metal enclosure and provide a tamper switch that activates the alarm in the event that the enclosure is tampered with.

(Review local telephone company requirements before making any changes.)

Install a Telephone Line Monitor

Most alarm systems can be equipped with a device known as a “telephone line monitor”. This device constantly watches the telephone line and can detect when the telephone line has been cut. The telephone line monitor can sound a buzzer on the premises to alert the facility owner when there is a problem with the phone line. The telephone line monitor can also be wired to sound an audible alarm (such as an outside siren) when the telephone line has been cut.

Most telephone line monitors use a simple electronic circuit to detect the presence of the telephone line and are not perfect. In some cases, the telephone line may be defective but the telephone line monitor will think it is OK. Telephone line monitors will also occasionally report that the telephone line is defective at times when it working fine.

Install a “Line Supervision” System.

Many alarm companies offer a “line supervision” type of alarm transmission system. These systems either use a special type of telephone line or send out a special signal over your regular telephone line. When the telephone line is cut or disabled, the central station is immediately notified. There are several types of line supervision systems, including multiplex, derived channel, and others. Most line supervision systems require that an additional monthly fee be paid to both the alarm company and the telephone company.

Install a Back-up Alarm Communications System.

For best security, install a back-up method of communicating the alarm signal to the central station. This type of system allows alarm messages to be transmitted even though the telephone lines have been cut. Two popular types of back-up communications systems are:

• Long-Range Radio Back-Up: This system uses a wireless radio signal to transmit the alarm signal between your premises and the central station. This type of system is reliable and cost effective but is usually available only in larger metropolitan areas. Also, this service may not be offered by all alarm companies.
• Cellular Telephone Back-Up: This system uses the cellular telephone network to transmit alarm messages to the central station when the regular telephone lines have been disabled. This system works with most digital communicators and is available anywhere that cellular telephone service is available. Cellular telephone back-up units are sold by almost all alarm companies.
• Internet Monitoring Connection: This system uses your internet connection to provide either primary or back-up monitoring of your alarm system. Verify that system that you choose is “supervised” and will notify the central station when the internet connection to your alarm system is lost. If your internet connection is a type that uses telephone lines (such as DSL), you may lose both telephone and internet when your telephone line is cut – but if the system is supervised, the central station will be notified.

Since security systems were invented, audible warning devices have been used to “sound the alarm” when the security system is activated. In earlier years, bells and vibrating horns were the type of audible device most frequently used. In more recent times, sirens and other types of electronic sounding devices are commonly used in place of the bell or vibrating horn.

In a modern building, there may be literally dozens of different types of audible warning devices in use. Fire alarm systems, emergency exit alarms, elevators, electronic article surveillance systems, access control systems, and intrusion alarm systems can each have their own audible warning device. In an industrial setting, there may also be audible warning devices on production equipment, assembly lines, and on forklifts.

With so many different types of audible warning devices in use, it is sometimes confusing to building occupants when an alarm sounds. Is it the fire alarm? An emergency exit alarm? Or has a piece of production equipment jammed?

A “voice messaging system” can be used to supplement or replace many types of traditional audible warning devices. As its name implies, a voice messaging system plays a human voice when it has been activated. For example, if the fire alarm system has been activated, a voice messaging system could be be used to play a warning message that says “The fire alarm system has been activated, please evacuate the building immediately.” The voice messaging system provides a clear and easily understood message to building occupants, and provides much more information than a simple bell or siren does.

Early voice messaging systems used an audio tape to record and play the message. These systems were expensive and not entirely reliable due to the potential for the tape to jam. Due to recent developments in electronic technology, there are a number of different types of digital voice messaging systems now available. These systems use an electronic memory chip to store the voice message and are very reliable.

There are two types of digital voice messaging systems available. The first type is what I call a “central voice messaging system”. The central voice messaging system works in conjunction with a building public address (PA) system. Central voice messaging systems are used to broadcast a message throughout the entire building. These systems are ideal for situations where it is necessary to warn all occupants of the building, such as when the building fire alarm system has been activated. Central voice messaging systems are available in versions that have 4, 8, or 16 or more separate message “channels”. Each channel has a unique voice message which can be activated separately. For example, if a building had four separate wings, a separate message could be played when the fire alarm was activated in a specific wing: “the fire alarm system in the West Wing has been activated...” or “the fire alarm system in the East Wing has been activated...”, etc.

The second type of voice messaging system is what I call a “stand-alone voice messaging system”. The stand-alone voice messaging system is a small self-contained unit that is designed to be used with one or two speakers. The stand-alone voice messaging system is ideal when it is necessary to broadcast a voice message only at a specific location. For example, a stand-alone voice messaging system could be used at a card reader controlled door in place of the traditional audible sounder. If the door was propped open, the system would play a voice message such as: “Warning – this door has been held open too long – please close the door behind you.” Stand-alone voice messaging system are available with one or two voice message channels. These systems can cost as little as $250 installed, making them inexpensive enough to use in a wide variety of situations.

There are endless possibilities for using voice messaging systems in security-related applications. I’m sure that you can think of several uses for these systems in your own facility. Here are a few applications that we have encountered:

• Large distribution warehouse: Central voice messaging system used to annunciate emergency exit alarms on exterior warehouse doors. Allows emergency exit alarm to be heard throughout warehouse; allows supervisors to quickly respond to specific door where alarm originated.
• Large office building: Central voice messaging system tied to intrusion alarm system, plays warning message when intrusion alarm system has been armed. Prevents false alarms caused by employees who may still be in building when the intrusion alarm system is turned on.
• Corporate headquarters building: Central voice messaging system connected to panic button installed at main receptionist’s desk. Activating panic button plays discrete message over building paging system to notify emergency response team that receptionist requires assistance.
• Hospital: Stand-alone voice messaging system connected to motion detector located at head of stairway leading to emergency exit door. Employees approaching the stairway are reminded that the door that they are headed to is for emergency use only and should not be used as an exit. Result: reduced false alarms.
• Heavy industrial facility: Stand-alone voice messaging system connected to motion detector located at entrance to chemical handling area. Employees approaching this area are reminded that they must carry respirator and other safety equipment when entering this area.
• Distribution center: Stand-alone voice messaging system connected to manual pushbuttons located at truck entrance to facility. Truck drivers can press button to receive specific driving directions to the destination to which they are headed.

Remember when your intrusion alarm system was first installed?

You may have experienced several false alarms during the first year that your system was in operation. Some of these false alarms may have been due to “user error”, caused by you or one of your fellow employees. Maybe you also had a false alarm or two due to defective equipment.

Several years have gone by and the false alarms seem to have disappeared. You dutifully turn your system on every night, and turn it off every morning. Everything seems to be working fine. Is it?

A test by one company of its intrusion alarm systems revealed some disturbing results. This company had Silva Consultants perform random tests at approximately fifteen of its facilities located within the western United States. The intrusion alarm systems at these facilities ranged from three to seven years in age and were installed by a variety of both local and national alarm installation companies. Some of the problems that we identified during these random tests included:

• Motion detectors in a warehouse that were completely blocked by inventory. In one warehouse that was examined, every interior motion detector was blocked by merchandise.
• Magnetic door contact switches that were disconnected from the system. Most of these switches were “temporarily” bypassed during service calls and were never reconnected to the system. At one facility, switches on 13 of the 28 overhead doors were bypassed.
• Glass breakage detectors that had their sensitivity setting set to zero. In an attempt to reduce false alarms, the system installer had set the sensitivity settings so low that even a hurricane breaking every window would not cause these detectors to set off an alarm.
• Alarm control panel that was disconnected from phone lines, preventing the monitoring center from receiving alarm reports. In one case, the customer had upgraded his telephone system more than three years earlier. The telephone line connections to the alarm panel were accidentally disconnected at that time, and the problem was not discovered for three years! All the time the customer was paying for monitoring and was feeling good because the system wasn’t having any false alarms!
• Defective control panel. Control panel allowed customer to turn system on and off normally, but would not send alarm to monitoring center when alarm was tripped. Problem later determined to be caused by lightning damage.
• Systems not properly interconnected. At one facility, a critical freezer temperature monitoring system was supposed to be connected to the intrusion alarm system to permit monitoring by the alarm company. Upon testing, it was discovered that the final connections between the two systems was never made – each installer had assumed that the installer of the other system would take care of the final connections. This problem existed in the system since the day it was installed and yet was not discovered until the system was tested by Silva Consultants two and a half years later.

The conclusion: intrusion alarm systems should be tested regularly to assure that they are in proper working order.

Suggestions for Testing

• Tests of intrusion alarm systems at “average risk” facilities should be conducted at least annually. Systems at “high risk” facilities should be tested at least quarterly. (Your insurance company may require more frequent tests.)
• Tests should be conducted by a company other than the one who installed and/or services the existing system. Alternatively, the system may be tested by the regular installation and service company provided that the tests are witnessed by the owner of the facility or the user of the intrusion alarm system.
• Every device in the system should be tested. Open every door, trip every motion and glass break detector, activate every panic button or hold-up alarm device. Remember, if it seems like too much trouble to test a particular device, it is likely that the system installer felt the same way when he first put in the system. These “hard-to-test” types of devices are the ones that need testing the most.
• If the system is monitored, have the monitoring center provide a written report showing which alarm zones were received and when. As most monitoring centers are now computerized, it is usually not a problem to have a report printed and faxed to you just after completion of the test.
• Disconnect the system from it’s primary power source to test the back-up battery systems. This can usually be done by simply unplugging the low-voltage transformer that is plugged into the wall near the panel. Operate the system for ten to fifteen minutes without power and then trip the system to make sure that it still works OK.
• If the system is monitored, unplug the connections between the alarm panel and the telephone lines. Leave unplugged for about five to ten minutes to make sure that the panel’s telephone line supervision feature is working correctly.