Security System

This section of the Ideas will cover basic security systems, installation issues, and integration with home automation. Every home automation system installation either provides for the security of the home or has provisions to incorporate new or existing security systems and equipment. The security subsystem of the home is responsible for not only the security of the home from intrusion from the outside, but the safety of the occupants and property from fire and other environmental hazards.
Security systems have been used in commercial buildings since the turn of the previous century, but have only been installed in home in any large numbers since the 1970's. They are now one of the most popular home subsystems, followed by HVAC and lighting. The scope of what the security subsystem does has also expanded to include everything from medial monitoring to video surveillance. This section will cover the basics of most security subsystem equipment operation, installation issues associated with the equipment and options for integration with automation systems.

Security System
Home Security

Security zone - a zone is typically defined by a group of sensors that monitor a specific area of the home or environmental condition. For example, all the downstairs windows, the perimeter doors, or the first floor interior spaces. Zones typically fall into three general areas: the house exterior areas such as a driveway, pool area, or entry area; perimeter entries or openings such as doors and windows, and interior areas such as room, hallways, or stairwells. A zone can also be assigned to safety related sensors such as smoke and heat detectors.

Security systems can generally monitor 8 to 16 zones. What the system does when an alarm condition occurs in a zone is programmed into the system when it is installed.

Armed/Unarmed - A security system is said to be armed if it will cause an alarm condition if a sensor input detects a condition that may threaten life or property. The alarm condition may turn on sirens, lights, and/or transmit the condition to a monitoring service (see below). A system may monitor sensors and report their condition for purposes of home automation functions without being armed.

Sensor - a sensor is any device that detects a condition that can be translated into an open or closed state. Sensors generally fall into three categories; intrusion sensors (the largest category) intended to detect actions associated with breaking into a home such as door and window magnetic sensors, fire related sensors such as smoke and heat sensor, environmental sensors such as water or carbon dioxide sensors, and medical related sensors such as medical alert pendants.

Monitoring - A security system is said to be "monitored" if an alarm condition (or other conditions programmed into the system) causes the system to transmit its alarm state to a service that will take appropriate action. Almost all security systems are capable of being monitored by a security service. For a monthly fee the service will call and dispatch local fire and police services as well as notify the home owners. The monitoring service acts as a "go between" the security system and local police/fire/medical services since these services will not accept calls directly from the security system.

Security System Overview
Security systems fall into two general categories: stand alone systems that operate independently from any other system in the home, and integrated systems that are usually part of a home automation system. Often the distinction between a home automation system and a security system is blurred and it is hard to tell whether a system is an alarm system with added home automation related functions, or a home automation system with security functions built-in.

This guide will separate the two systems and discuss stand alone systems followed by systems integrated with home automation systems.

The other major division of systems is based on how the sensors or other input/output devices connect to the system: hardwired meaning they connect primarily by cables; or wireless meaning they connect primarily by RF signals. Wired and wireless systems operate almost identically and are primarily intended for new construction installation and retrofit installation respectively.

Security Panel System
Typical security system components

The panel is intended to be mounted in the equipment room or central distribution point in the home-the same location that structured cabling or other equipment is located. It contains the main control logic electronics of the system.

The cables to all sensors and other devices (keypads, alarms, etc.) originate at the panel. Most panels use an external 12 or 24 Volt power supply, plugged into an outlet strip but some have a built-in supply. They will always contain a backup power battery to supply power to the system, typically for 6 to 12 hours, if house power fails. The battery will furnish power for everything attached to the system (for wired systems). The panel will also monitor battery power and provide an alarm condition if the charge state is too low. Programming the system is typically done by attaching a PC to the system at the panel.

The keypads provide the user interface for the system. They may be very simple, using only a few buttons and LEDs, or very sophisticated with graphic displays and a range of alpha, numeric, and special function keys. Most systems can accept several keypads that act in parallel. Keypads are usually placed near entryways to the home such as a front hall, back hall, and in the master bedroom so the system can be easily armed or disarmed when leaving or returning home. Keypads will always have a way to arm and disarm the system, with keys to allow the user to input an access code (usually 4 to 7 numbers).

Sensors are remotely located throughout the home to detect some action that causes the panel, depending on security state of the home (armed, disarmed, and so on), to either do nothing, cause an alarm condition, notify the occupants, notify a monitoring service, and so on. While there are dozens of different types of sensors, from simple magnetic door sensors to complex microwave motion sensor, they all produce the same "output": either the sensor is "open", meaning an electrical circuit path is open, or "closed", meaning an electrical circuit path is made. For example, the contacts on a magnetic door sensor is usually closed when the door is closed and open when the door is open. The security panel simply detects an electrical open or closed condition and is unaware of what type of sensor is attached. Since all sensors work basically the same way, they can be substituted or combined in almost any combination.

Alarm devices provide some highly audible or visual indication that an alarm condition has occurred. The most common are sirens, bells, or horns that provide a loud alarm noise to alert occupants, neighbors, or the police. Alarms come in both inside versions (to alert occupants) and weather resistant outside versions. Outside alarms can also be placed in protective enclosures. Alarm devices are also available that output voice messages such as "Intruder alert", "burglary, burglary, the police have been called", "fire in upstairs bedroom", intended to scare away intruders or give occupants more information about the alarm condition.

Annunciators are similar to alarm devices but are used primarily to alert occupants to anything from door openings, to someone around a pool area. They can be simple buzzers, chimes, or voice generators.

A monitoring interface allows the alarm system to use a security monitoring service. A monitoring service will notify the police, owners, your company, or anyone else on a notification list if an alarm occurs. They can also be used to filter false alarms by calling the house to verify if an alarm was accidental. A monitoring interface (usually built into the panel electronics) typically uses a phone line to dial the monitoring service computer system. Once connected, the interface will convert the alarm condition to a standardized digital code that is transmitted to the monitoring service. The monitoring interface can also use a cell phone connection or other wireless system to connect to the monitoring service.

Sensor wiring for series and parallel combinations

Sensors that have normally open contacts can be wired together with other normally open devices in parallel. If any sensor is closed (alarm), an alarm will be detected. If more than one sensor enters a closed state, it is not possible to tell which sensors are in alarm.

Many sensors, such as smoke detectors and infrared motion sensors, require DC operating power, usually 12 volts DC. This power is usually provided by the power supply in the panel and wired to the sensor using an extra set of wires in the cable from the panel to the sensor.

Perimeter zones are on the house perimeter and usually consist of entry doors, garage doors, and windows. Perimeter zones are used to generate intruder alarm conditions as well as for monitoring.

Interior zones are on the inside of the house and typically include motion sensors on each floor, halls, or basements, but can also include sensors on cabinets, drawers, or other interior locations. Interior zones are also used to generate intruder alarms as well as monitor for activity.

All systems include one or more fire/smoke "instant alarm" zones used for attachment of smoke and/or fire sensors. There may also be a "panic" or "medical" zone. A panic zone can be connected to buttons or other sensors activated by the occupants to indicate that an intruder has gotten into the house (perhaps disguised as a salesman). This will cause a "silent" alarm to be sent to the monitoring service to summons the police.

A medical zone is usually assigned to buttons or wireless pendants around the home that, when activated, will cause a medical alarm and alert the monitoring service to send medical help.

The security system will generally provide for a fixed maximum number of zones that can be wired to the panel. Each zone consists of one or more sensors wired together in either a series (most common) or parallel configuration.

In some systems, the function of each zone can be programmed, while in others, they are fixed and defined by a specific set of screw terminals in the panel where the sensors for the zone are attached.

Most security systems allow the installer to custom program the system for the individual installation. Some of the more typical programming parameters include:

pass-codes - one or more multi-digit codes for the occupants.

entry/exit delay - the entry and exit delay times in seconds.

zone operation - assignment of zones to exterior, interior, perimeter areas or inclusion in each type of arming mode.

alarm conditions - what to do when an alarm is detected (sound alarm, annunciation, notify monitoring service).

monitoring parameters - monitoring service information such as account numbers, alarm codes, etc.

Programming can be done from the keypad (upon entering a "supervisor" or "installer" code) or by an attached PC via an RS242 port on the system panel. Once programmed, the system will retain the input values in a nonvolatile memory to prevent loss in case of power failure.

Wireless Systems
While wireless security systems are primarily intended for installation in existing homes, there is no reason they can't be installed in any home. Wireless systems operate nearly identically to wired systems except the connection to the sensors (or other components) is by RF signals.

This means that all the sensors will need to have a battery. Typically on small sensors such as magnetic door and window sensors, the sensor is actually hardwired for a short distance to the RF transmitter unit. The transmitter can be mounted out of sight behind curtains, blinds, and so on. Connection to alarm devices is also via RF. Alarm device may plug into an AC outlet but may also be battery operated.

Typical security system panel with plug-in power supply, backup battery, and keypad. The processor board has screw
terminals to connect sensors alarms and keypads.

We carry more than 10 different security systems please ask us which one is the best for you

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