Security System Basics

Security SystemBasics

In this chapter, you will learn about

  • Residential security systems types
  • Security system devices
  • External security services

Numerous studies have shown consistently that the homes with the most risk of crime typically have the least protection. And in a significant percentage of these homes, there is no protection or warning systems installed, beyond door locks and fencing, that is. Those homes that do have some type of protective system, commonly have some form of burglar alarm, but even this is only common in more expensive homes.

Of course, protection is the main purpose of a security system. However, the primary benefit of a residential security system is not necessarily protection, but rather the peace-of-mind that comes from having a security system installed.

The type and technology of a residential security system should be fitted to the home, lifestyles, and the level of protection desired by the homeowners. In this chapter, we look at security system basics, including the various types of systems available, their components, the communications technologies they employ, and a few of the external services that can be used for monitoring.

Residential Security Systems

A home security system provides protection at two levels: interior and perimeter. Interior protection includes the detection of, and an alarm for, events inside the home, including:

  • Someone moving about inside
  • Someone breaking into a cabinet, cupboard, or the like
  • Smoke, fire, or carbon monoxide gases
  • Environment sensors

Perimeter protection provides detection of, and an alarm for, events such as:

  • A door opening
  • A window breaking
  • Someone in the yard
  • Unauthorized access to the property

Reactive Vs Proactive Security

Traditional security systems are “reactive” in that they react to an intruder and sound an alarm. This alarm usually scares the intruders away, warning them that they have been detected and that the local authorities are probably already on the way. But the alarm is in response to the intruder already being in the home and jeopardizes the safety of the occupants.

By integrating a security system with home control, the system can be “proactive” in that it will increase the safety of the occupants by lighting the way outside when the smoke alarm goes off or lighting the walkway when they arrive home late at night. It can deter the potential intruder from selecting the home to break into as the home can have the “lived-in look” when the homeowners are away.

Interior Protection

The function of interior detection is to protect a home’s occupants and contents from intruders and keep them safe. The primary features of interior security include:

  • Access controlA process that allows or denies access, or entry, to the home itself or to a particular area. Typically, access control systems require the entry of codes, the use of a key, an access card, a proximity card, or a physiological characteristic of a person, such as hand or thumbprint. Access control can be as simple as a mechanical lock and key or as sophisticated as biometrics (which is an access control method that uses fingerprints, retinal scans, and the like).
  • Intrusion detectionThe opening of a door, a window breaking, a shock or vibration on a surface, or even a motion in a secured area can create a notification or an event that triggers an alarm to sound or sends an intrusion alert message to an external security monitoring service that then contacts the local police and fire departments.
  • Smoke, fire, and dangerous gas detectionIndependent or integrated sensors can detect smoke, the heat from a smokeless fire, and even carbon monoxide or radon gases and sound a built-in alarm, send an alarm signal to a central security system controller, or relay a message to an external security monitoring service.
  • Panic buttonsThough they are not found in all security systems, a panic or emergency alert feature can be a desired feature for some customers. Typically, a centrally or conveniently placed button or a special sequence of digits on the telephone or alarm keypad can be used to sound an alarm or to transmit an emergency request to the monitoring service to dispatch the local emergency services or the police department.
  • Environment sensorsOptional temperature and humidity sensors can be installed to monitor the environment. Low temperature sensors can detect when the heat goes too low and notify the monitoring service or indicated parties prior to the pipes freezing and bursting. Humidity and temperature sensors help maintain the correct environment for wine cellars and cigar rooms. Flood or water sensors can detect when water is at a level it shouldn’t be, such as what occurs when a sump pump fails or a pipe breaks in the basement.

Perimeter Protection and Detection

The primary purpose of perimeter protection is detecting intruders in the area around a home before they attempt to enter it. In addition, exterior detection can make it a safer place for the homeowners and their guests when it is interfaced with the outside lighting. The primary features of perimeter protection and detection are

  • Access controlGates or an entryway onto the property can be secured and entry granted to only those people the homeowners allow to enter through a remote control or remote switch or those people who know the security code or have an access card.
  • Intruder detectionIf intruders enter the secured space around a house, the system should detect their presence and perform a variety of optional security functions, such as signaling the lighting system to turn on the exterior lighting after dark, sounding an alarm, alerting the homeowner, or contacting a monitoring service after hours.
  • Glass breakage detectionBecause double-paned glass is common on most new homes, sensors should also be placed on the exterior windowpane to detect an intruder attempting to enter the home by breaking through a window.
  • Screen breakage detectionBy placing a sensor on the screen frame or using special screen woven for security detection, an alarm signal can be sent to the security system if the frame is removed or the screening cut.

Security System Components

Many residential security systems come with a certain number of features and components, such as hard-wired systems with a control panel, an RJ-31x interface, multiple zone inputs, and a keypad controller and wireless systems that include a control panel, sounder (alarm), keypad, window or door contacts, and a remote control. Different manufacturers offer different systems, packaged with what they believe to be the most commonly used features, components, and devices. However, it is virtually impossible for a manufacturer or reseller to know exactly which features and devices a specific house requires for its security system installation. This is why most of the components needed are offered as options.

Regardless of whether of not a system is a wireless or hard-wired system, and most of the newest systems can be adapted to include both, the most commonly used components are available for use with either type of system. The most commonly used security system components and features include:

  • Security control panelThis central device in the security system serves as both a command center and a distribution point for the devices and features connected to or managed by the system. Choosing a security control panel for a home means choosing one that has the capacity to support the number and type of devices to be installed and one that supplies the feature set that’s both desired by the homeowner and required by the security system design. Hard-wired control panels are typically enclosed in a cabinet and installed near a home’s central distribution panel. Figure 31-1 shows a power line control (PLC) wireless control panel.

    click to expand
    Figure 31-1: A PLC wireless security system control panel

Photo courtesy of Smarthome, Inc.

  • KeypadsVirtually every residential security system includes a keypad (see Figure 31-2), the homeowner’s primary interface and input device for entering setup parameters and setting security system features on or off. Many hard-wired systems also provide a computer connection and control software that allows these functions to be performed from a PC terminal. Many keypad models also provide wireless remote access through a PLC relay, a handheld remote control, or a key fob control.

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    Figure 31-2: A residential security system keypad

Photo courtesy of GE Interlogix.

  • SensorsThere are a variety of sensors that can be installed as a part of a home security system; each designed to detect a different event. Table 31-1 lists the more common sensors used in home systems and their functions.

    Table 31-1: Residential Security System Sensors and Their Functions

    Sensor Type


    Water/flood sensor

    Detects the presence of water in an area where it shouldn't be. Used for such things as spa overflow, pipes breaking, and sump pumps failing.

    Low temperature sensor

    Detects when the temperature goes below a preset temperature.

    Humidity sensor

    Detects when the humidity goes outside of a preset range.

    Natural gas sensor

    Detects the presence of natural gas in the air

    Carbon monoxide (CO) sensor

    Detects the presence of a higher than normal level of CO in the air.

    Contact sensor

    Detects the opening or closing of a window or door in opposition to its normal state, either Normally Open (NO) or Normally Closed (NC).

    Glass-break sensor

    Detects the sound of shattering or breaking glass.

    IR beam sensor

    Detects when the line of an IR beam is broken.

    Floor mat sensor

    Detects the pressure on a thin surface. Often placed below the carpet on steps to detect someone coming upstairs.

    Shock/vibration sensor

    Detects the presence of natural gas in the air.

    Heat sensor

    Detects rapid changes in an area's temperature using a metal strip that either melts or changes shape when exposed to higher than normal temperatures. Many smoke detectors have heat sensors built in.

    Motion sensor

    Uses passive infrared (PIR) technology to detect movement in an area. Sensitivity can be adjusted to only detect objects over a certain size and weight or the lens can be masked out to not see pets below a certain sight line.

    Smoke detector

    Uses an ionization chamber or a photoelectric cell to detect the presence of smoke in the air. Smoke detectors typically have an internal alarm as well as a relay to send an alarm signal to the central unit. See Figure 31-3.

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    Figure 31-3: A cut-away view of the internal components of a residential smoke detector and alarm device

Photo courtesy of GE Interlogix.

  • Alarms, sirens, and soundersNearly all security systems include some means to alert a home’s occupants of an intruder, smoke, or other security event. In most cases, this is an internal siren, alarm, or sounder circuit that activates an external sounding device. Table 31-2 includes the most commonly used terminology regarding security systems and alarms.

    Table 31-2: Common Security Features and Devices

    Security System Feature

    Devices Used to Implement the Feature

    Perimeter detection

    Sensors, such as contact sensors, placed on exterior doors and windows that activate an alarm.

    Interior detection

    Sensors, such as motion detectors and smoke detectors, placed in the interior of a home excluding windows and doors.

    Silent alarm

    An alarm that notifies a monitoring service that an alarm event has occurred but there is no alarm sounded in the home to alert the intruder.

    Local alarm

    A siren or bell that is sounded in or outside of a home with no other notification made.

    Silent/audible alarm

    A switching feature on security systems that allows the alarm to be silent when a home is unoccupied, but sounds a siren or bell when occupants are in the home.

    Digital dialer

    An electronic device that uses an RJ-31x connection grabs the phone line to place a telephone call to a monitoring service and then verifies the connection and sends an alarm activation message.

    Line seizure

    An RJ-31x connection is used to capture and hold a telephone line until an alarm call can be made and completed. When it seizes the line, it hangs up any phone connection already in progress.

  • RJ-31x interfaceMost of the better residential security systems include an RJ-31x jack that facilitates a specialized feature on a standard telephone line called line seizure. The RJ-31x interface is used when a security event triggers a call to be placed to a homeowner’s remote telephone number, cell phone, or pager, or to a security monitoring service. By seizing the phone line, the security system is able to disconnect any calls on the line and use the phone line to make its security notification call.
  • Hard-wired sensor converterThis device is used to adapt existing sensors, such as a door or window contact into a wireless device.
  • Cameras and monitorsSecurity cameras and monitors can be part of a security surveillance system.


    Surveillance systems, including cameras and monitors, are covered in Chapter 35.

Security System Connections

Residential security systems use two means to link their sensors, detectors, and alarms to the control unit: radio frequency (RF) signals and wire or cable runs. Wireless RF-based systems don’t require unit-to-unit wiring and typically provide the most flexibility during installation but do require ongoing maintenance because the detection devices operate on batteries. Hard-wired systems must be pre-planned so that the appropriate cabling can be installed during the pre-wire phase of a new construction or a remodeling project.

Hard-wired systems generally offer a better quality signal than a wireless system, provided the cabling used is installed to specification. However, as wireless technology continues to improve—for example, as a larger number of communication channels are added—wireless systems are proving to be much more reliable.

Another difference between wireless and hard-wired systems is the initial cost factors. Wired system components are generally less expensive than the wireless versions, but part of the cost savings realized with a hard-wired system is eaten up with the cost of the cabling and its installation. Over time, the wired system usually lasts longer because the components do not include the advanced technology that is present in wireless systems.

Hard Wired Security Systems

In many residential situations, a hard-wired security system has some advantage over a wireless one. A hard-wired system directly and physically connects the components of the system—the contacts, sensors, and so forth—to the main unit with a cable or wire. The primary benefit of the hard-wired approach is that unlike a wireless system, the hard-wired system is significantly less sensitive to electromagnetic and radio frequency interferences, especially if the system’s wiring was properly installed.

Hard-wired systems are made up of a main security control panel, like the one shown in Figure 31-4, which is connected to the system’s contacts, sensors, alarms, keypads, and other devices with home run wires. Understand that the illustration in Figure 31-4 is highly simplified and that the controller unit is typically centrally located with the devices wired into it attached to home run wiring and located throughout a home.

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Figure 31-4: An illustration of the control panel and wiring leads of a hard-wired security system

Hard-wired systems are certainly easier to install during a new construction project, but they can also be retrofitted to a home provided there is open wire run space in an attic, basement, or crawl space.

Wiring a Hard-Wired Security System

In general, hard-wired security systems recommend the use of 2-conductor or 4-conductor cabling that should be planned along with the structured wiring plan during the design phase and installed during the pre-wire phase of the project. However, there are wiring guidelines (minimum cable recommendations) for use with different security system components. Table 31-3 lists the more commonly used components and the recommended wiring or cabling to connect them into a hard-wired security system.

Table 31-3: Wire and Cable Guidelines for Hard-Wired Security Systems

Security System Component

Wire Recommendation


Standard: 22 AWG 4-conductor stranded

Advanced (with voice pick-up and playback): 2 runs of 18 AWG 2-conductor shielded stranded

Internal and external alarms, speakers, and sound devices

18 AWG 2-conductor copper wire

AC power connections

18 AWG 2-conductor copper wire

Motion sensors, glass break detectors

22 AWG 4-conductor copper wire

Door and window contact sensors

22 AWG 2-conductor copper wire

Fire alarm connections, smoke detectors and heat detectors

FPLP (fire power limited plenum) cable or FPL (fire power limited) cable: 18 AWG 4-conductor

Ground connection

14 AWG 1-conductor copper wire

RJ-31X console

22 AWG 4-conductor copper wire minimum, CAT 3 or CAT 5 preferred

Wireless sensors

Any of the above sensors but RF communications and batteries power them, so no wiring is required

Video monitors and video capture devices

RG-6 coaxial cable

Wireless Security Systems

Depending on how technically you define the term wireless, wireless security systems can be either completely wireless RF-based systems, powerline (PLC such as X-10) technology systems, or both.

“Wireless” Wireless Systems

Wireless security systems typically provide the same functions as hard-wired systems, especially with the expanded RF range (around 600 feet) of some newer products. Essentially, a wireless system requires only that a main control unit, like the one shown in Figure 31-5, be connected to an AC power source and the system is ready to use. Of course, sensors, detectors, and other devices need to be installed where appropriate, but these operate on self-contained batteries. The main benefit of a wireless system is that no wiring is required.

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Figure 31-5: A wireless main unit needs only to be plugged in to activate the system

Photo courtesy of General Electric Interlogix.

Wireless systems allow for flexibility when defining multiple wireless security zones and some systems can also be connected into an existing wired security system to extend the original system or replace the wired system control unit.


See Chapter 32 for more information on designing security zones.


One consideration about using wireless devices is that the detectors and sensors are typically battery operated, which means that although these devices normally have a long battery life, the batteries do need to be replaced on a regular schedule, such as every six months.

External Security Services

Some security systems can be programmed to call a phone number (residence, friend, cell phone) when the system goes into alarm, but this does not notify or dispatch the police. This system depends upon someone answering the call at the time it is received, listening to the message, and responding immediately.

Some homeowners prefer to have someone outside the home monitoring their home security system because it gives them the assurance that there is always somebody to summon help when there is a break-in or an emergency. This involves a recurring monthly fee. For these homeowners, there are two basic types of external security services available:

  • Alarm monitoring
  • Remote viewing monitoring

Alarm Monitoring Services

Alarm monitoring services are usually connected to a home through an RJ-31x connection that places a call to the service’s monitoring system and communicates digitally, whenever the security system is breached and an alarm event is triggered, regardless if an alarm sounds in the home or not. The connection to the monitoring company can also be through a cell phone or long-range radio. Some security systems allow for the monitoring service staff to “listen-in” through the security keypads in the home. The security system may even provide two-way voice communication between the monitoring service staff and the occupants of the home.

Some companies will work with the installer and the homeowner to design a security system that best provides the security level desired and then contract for the alarm monitoring services for that system. Most, if not all, city and county police and sheriff departments no longer provide alarm monitoring and security review services and only respond to calls from security monitoring services. Many municipalities also have a policy of charging the homeowner for repeat false security alarm calls.

The upside to alarm monitoring services is that they are always there—24/7—and are to respond immediately. The downside is that because they are off-site, and especially in cases when the homeowner is away from home, they can dispatch the police or fire department to investigate the cause of an alarm. Should the problem be caused by something other than an intruder, such as a branch blown through a window or an alarm caused by an electrical fault, the homeowner can be charged a fine for a false alarm.

Remote Viewing Monitoring Services

Another type of residential security services is remote access monitoring services, which use surveillance cameras and microphones to monitor a home’s interior and exterior for unauthorized access or presence.


See Chapter 35 for more information about the types of service provide by monitoring services.


A home security system can be either “reactive” or be interfaced to a home control system and be “proactive.” A security system provides protection on two levels: interior and perimeter. Interior protection systems include detecting and sounding alarms in response to events inside and outside a home. The function of interior detection is to protect a home’s occupants and contents from intruders. The purpose of exterior or perimeter protection is detecting intruders in the area around a home before they attempt to enter the house.

A residential security system links to its sensors, detectors, alarms, and control units using either radio frequency (RF) signals or wire or cable runs. Wireless RF-based systems don’t require unit-to-unit wiring. Wireless security systems can be completely wireless RF-based systems or interfaced to wired systems. Hard-wired systems must be pre-planned so that the appropriate cabling can be installed during the pre-wire phase of a new construction or a remodeling project.

A hard-wired system directly and physically connects the components of the system—the contacts, sensors, and so forth—to the main unit with a cable or wire. The primary benefit of the hard-wired approach is, unlike a wireless system, a hard-wired system is significantly less sensitive to electromagnetic and RF interferences, especially if the system’s wiring is properly installed to avoid interference sources.

Common devices and features of a residential security system include a control panel, a RJ-31x interface, multiple zone inputs, alarms, window or door contacts, a remote control, and a keypad controller. An important feature on systems that support alarm monitoring is an RJ-31x interface.

Two basic types of external security services are available: alarm monitoring and remote video monitoring.


  1. Which of the following is not a common feature of a residential interior security system?

    1. Access control
    2. Intrusion detection
    3. Perimeter intrusion detection
    4. Smoke or fire detection
  2. What communications technology is used by a truly wireless system?

    1. PLC
    2. HomePNA
    3. Cat 5e
    4. RF
  3. A security system integrated into a home system controller is said to be

    1. Intrusive
    2. Preventive
    3. Proactive
    4. Reactive
  4. What type of alarm only notifies a monitoring service that an alarm event has occurred?

    1. Silent alarm
    2. Local alarm
    3. Digital alarm
    4. Zone alarm
  5. What device is used as the homeowner’s primary interface to a security system?

    1. Control panel
    2. Keypad
    3. Remote control
    4. Personal computer
  6. What is the specialized connection used in security systems to seize a telephone line for purposes of notifying an alarm monitoring service of a security breach?

    1. RJ-11
    2. RJ-12
    3. RJ-31
    4. RG-6
  7. What type of sensor is used to detect the opening or closing of a door or window?

    1. CO sensor
    2. Glass-break sensor
    3. Contact sensor
    4. PIR sensor
  8. If a homeowner wishes to have an outside party take action on security and alarm events that are triggered, the type of firm contracted would be a

    1. Remote monitoring service
    2. Alarm monitoring service
    3. Remote alarm management service
    4. Alarm security service
  9. Which of the following is not a form of a security system’s interior protection?

    1. Someone moving about inside a home
    2. Someone breaking into a cabinet, cupboard, or the like
    3. Smoke, fire, or carbon monoxide gases
    4. A door opening
  10. Which of the following is not a protection provided in a perimeter security system?

    1. Access control
    2. Smoke, fire, or carbon monoxide gases
    3. Glass breakage detection
    4. Screen breakage detection


  1. C. Interior systems, which should be obvious from its name, include all security measures placed inside a home. The other choices are all typically included in an interior security system.
  2. D. Radio frequency (RF) signals are used by wireless systems to communicate. X-10, which is a form of wireless system, uses existing powerlines to communicate; Cat 5e is a networking cable standard; and HomePNA (Home Phoneline Networking Alliance) is a standard for communications over interior telephone lines.
  3. C. Security systems that are integrated into a home automation control system provide proactive security.
  4. A. This alarm doesn’t sound an alarm locally, but notifies the monitoring services. An audible alarm can also notify services although it also sounds an alarm. A local alarm sounds a siren or bell without notification action. The term digital alarm is erroneous; a digital dialer is the mechanism used to notify the monitoring service.
  5. B. Regardless of the system type, hard-wired or wireless, the homeowner’s interface to a security system is primarily through a keypad. However, a PC can be used with most hard-wired control panels and a remote control can be used to activate or de-activate the alarm system.
  6. C. Actually, the connection is an RJ-31x. RJ-11 and RJ-12 are one-and two-line telephone line connectors and RG-6 is a coaxial cabling standard.
  7. C. This sensor detects that it has been either opened or closed, depending on whether it is set to Normally Open (NO) or Normally Closed (NC). A CO sensor detects carbon monoxide gas; a glass-break sensor detects the sound of breaking glass; and a PIR (passive infrared) sensor is a motion detector.
  8. B. A remote monitoring service performs video surveillance on a property and the other choices are just plays on words.
  9. D. Detecting an exterior door opening is a part of a perimeter security system.
  10. B. Smoke, fire, and CO detectors and alarm systems are classified as components of an interior security system.

Part I - Home Technology Installation Basics

Part II - Structured Wiring

Part III - Home Computer Networks

Part IV - Audio/Video Systems

Part V. Home Lighting Management Systems

Part VI - Telecommunications

Part VII - HVAC and Water Management

Part VIII - Security System Basics

Part IX - Home Technology Integration

Part X - Appendices

HTI+ Home Technology Integrator & CEDIA Installer I All-In-One Exam Guide
HTI+ Home Technology Integrator & CEDIA Installer I All-In-One Exam Guide
ISBN: 72231327
Year: 2003
Pages: 300 © 2008-2020.
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