Today’s businesses reply on their communication systems to stay competitive. Communication systems cover a wide range of voice, information processing, and signaling systems used to connect users together or to share information.
Five categories of communications systems in commercial buildings need structured cabling systems. These are:
- Phone systems
- Data systems
- Local Area Networks (LANs)
- Building Automation and Control Systems (BACS)
- Sound Systems
Each type of system is defined by NEC (National Electrical Code) in different sections of the NEC. Each system requires its own cabling system and usually is bid and built by separate contractors.
Most commercial businesses require more than one phone line, so that employees can receive phone calls while other employees are making phone calls. This is supported by a phone switch. Each telephone is connected to the phone switch using UTP (Unshielded Twisted Pair) copper cable. This is shown in the following figure.
> Small Business Phone Systems
Small businesses with fewer employees typically use small phone switches called Key Service Units (KSU). A KSU is designed to support a fixed number of phone lines and telephone extensions. A typical KSU supports up to eight phone lines coming from the Local Exchange Carrier (LEC, the phone company), and up to 32 telephone extensions. A KSU phone system is shown below.
> Large Business Phone Systems
Large businesses with hundreds or thousands of employees need a large phone switch called PBX (Private Branch Exchange). PBX can support hundreds of phone lines from the LEC (phone company) and thousands of telephone extensions. PBX systems can cost hundreds of thousands of dollars.
The term Data System is typically used to describe a mainframe or minicomputer system. It is not used to describe today’s popular PC-Server LAN (Local Area Network) systems.
> Mainframe Computers
Mainframe and minicomputer data systems were popular in the 1960s, 70s, and 80s. They have mostly been replaced by LAN (Local Area Network) systems. (We will talk about LAN in the next section).
A mainframe is a large, centralized computer that performed all computing activities. All applications were installed on the mainframe computer, and all data was stored on the mainframe computer’s disk drives.
Users interacted with the mainframe computer through terminals which were connected to a port on the mainframe’s controller with a communication cable. A mainframe computer could support hundreds of terminals. A mainframe computer was powerful enough to support an entire company.
A minicomputer is a smaller version of the mainframe computer. All applications ran on the centralized computer system and all data was stored on the minicomputer’s disk drives. Users interacted with the minicomputer through terminals which were connected to a port on the minicomputer with a copper cable.
Because minicomputers were not as powerful as mainframes, they supported only small number of terminals.
LAN (Local Area Networks)
In 1980, IBM produced the first Personal Computer (PC) and LAN (Local Area Network) was designed to link PCs together and enabled them to communicate. The term LAN is defined as “a data communication system allowing a number of independent devices to communicate directly with each other and within a moderately sized geographic area.”
The following picture shows a small LAN network.
A LAN is composed of at least of the following components.
- Network Interface Card (NIC)
- Communication cable
- LAN hubs or switches
Each station on the LAN must have a dedicated cable connection to a port on the hub.
Building Automation and Control Systems (BACS)
Building Automation and Control Systems (BACS) are build systems that regulate a building’s environment or monitor it for safety or security purpose.
BACS systems use a centralized control unit and distributed sensors or devices. Each sensor is connected to a port on the centralized control unit with a cable. The cable may also provides power from the central unit to the sensor.
The following systems are all part of a BACS system.
- HVAC (Heating, ventilating, and air conditioning)
- Fire Alarm
- Security, access control, and CCTV (closed-circuit television)
> HVAC (Heating, Ventilating, and Air Conditioning)
The HVAC system provides building temperature, humidity, and environmental control. It has a centralized control unit, and thermostats placed throughout the building.
Thermostats are connected to the control unit with cable and preset thresholds will trigger the centralized control unit to turn on a mechanical system to adjust the air pressure, rate of air flow, and fan speeds.
> Fire Alarm
A fire alarm system consists of the follow components.
- Lights and horns
The centralized fire alarm control panel is responsible for the detection, suppression and notification of fire. Fire alarm sensors are wired to a port on the control unit. If the centralized control panel receives a signal from a sensor indicating a fire condition, it may activate the suppression and notification devices.
The following figure shows a typical fire alarm communication system configuration.
The fire alarm system can also integrate with security and access control system to unlock security doors and to enable automatic doors to be manually opened to provide escape routes. It can also integrate with the electrical system to operate emergency lighting and perform elevator capture to prevent their use during a fire.
> Security, Access Control, and Closed Circuit Television (CCTV)
Security systems include the following types:
- Alarm systems to provide intruder detection
- Control system to provide restricted access to specific areas of a building
- Closed circuit television systems to provide 24-hour surveillance of building grounds and building spaces.
Security systems are often integrated with access controls systems together.
1) Security System
The security system is made up of the following components:
- A centralized control unit
- Magnetic contact points
The sensors and magnetic contacts are distributed throughout the building and connected back to the control unit with communication cable. The security system monitors glass breaking, motion, or separation of the magnetic contact points on doors and windows.
2) Access Control System
Access control system is made up of the following components:
- A centralized control unit
- Access points
Access points are connected to the control unit with communication cables and they are magnetic card readers, key pads, or a type of biometric sensing device. The access point sends user’s information to the control unit, and the control unit send the signal to open the door if user is verified.
3) CCTV System
Closed Circuit Television system is a video network for security purpose. It is made up of video cameras placed throughout a building and campus. The video cameras are wired to a headend with coaxial cable. In turn, the headend sends the video signal to television monitoring sets in a security office. A typical CCTV system is shown below.
Sound systems include overhead paging systems and audio systems. Sound systems are used buildings for many people, such as airports, department stores, and sport stadiums. Overhead paging system is used to broadcast messages in a building such as airports and sport stadiums. Audio systems are used in department stores to distribute music and create a pleasant shopping environment.
A typical sound system is composed of the following components:
- Sound source
- Communication cable
The following figure shows a typical sound system configuration.