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Signalling Systems

Fire Alarm and Security Systems

A fire alarm is supposed to protect the people first, and the property second. They have audible and visual signals to warn people. These alarms help people evacuate and alert fire department personnel to aid in removing the threat.

Classifications of Fire Alarms

Single Stage (Unsupervised)
Schools, Apartment Buildings - Alarm goes off in the whole building once initiated.

Two-Stage (Supervised)
Hospitals, Airports, Shopping Malls - Alarm goes off only after it has been `keyed` by authorized personnel.

The Basic Elements of a Fire Alarm

Input (Initiating Devices) - sends a message to the control unit to warn
1) manual pull stations (installation height minimum 1.2m, maximum 1.4)
2) heat detector
3) smoke detector
* called "inputs"

Control Panel (The "Brain") - this is the panel that activates the "outputs"
(installation height 1.8m - legends to top of panel being maximum 2.4m)

Output (Signal Device) - sends an audible or visual alarm
1) Fire bells (installation height maximum 1.8m, at least 50 mm from ceiling)
2) Speakers
3) Strobes

Ancilliary Devices - are activated by contacts in the control panel
1) Fan shut downs
2) Damper closures
3) Door holders and fire door releases

Annunciator Panel - These panels have a visual indication of where the trouble occurred. There must be audio and visual alarms on these panels. Depending on the amount of zones required for the installation, there could be a requirement for a panel to be installed at the main entrance so that fire fighters can enter the building and immediately see where the trouble is.

Types of Fire Alarms

Type #1
-any device that activates all alarms
-not permitted in buildings with an annunciator
-single stage

Type #2
-any device that activates all alarms
-has an annunciator
-single stage

Type #3
-any device that activates coded signals
-has an annunciator
-single stage

Type #4
-any device that activates a distinctive alert
-has an annunciator and keyed operated alarms
-two stages

Type #5
-any device that activates a distinctive alert
-has an annunciator and keyed operated alarms
-two stages
-indicates the zone the alarm was indicated in

Canadian Electrical Code

Fire Alarm Section - (32) Highlights of that section are as follows:

16 AWG for individual conductors pulled into raceways (less than 300v)
19 AWG for individual conductors laid into raceways (less than 300v)

Conductors will be installed independent of all other

Must have a separate circuit and disconnecting means shall be colored red, and lockable in the closed position.

In a dwelling unit to have smoke alarm supplied by a circuit with a mix of lighting and receptacles.

A separate transfer switch is required for each fire pump

Classes of Wiring

Class A or B Fire Alarm Wiring

Class A is addressable. It also does not disable devices downstream when there is a device disconnected or an open circuit. It is supplied from two directions.

Class B is not addressable. It disables devices downstream when there is an open circuit. It requires an end of line (EOL) resistor. If this resistor is too high of a resistance it will indicate trouble on the panel.


- a defined location covered by initiating devices in one circuit ( or zone)
- when it is activated, it can easily be detected
- a typical zone could be a floor or a wing

Addressable Systems

- can contain multiple circuits
- can log events, trouble, etc
- can program from laptop
- verifies wiring
- verifies devices
- verifies locations

Security Systems

The purpose of a security system is to provide:
1) Deterrence
2) Prevention
3) Detection
4) Response
5) Apprehension

Layers of Protection

The layers of protection refers to the onion skin analogy.
1) Perimeter - Outer perimeter of home or building
2) Space - motion detector, no worry of point of entry
3) Spot - specific areas

Three Components of an Alarm System

1) Detection circuit (secure/ insecure)
2) Control circuit
3) Output circuit

Alarm System Wiring

Two Wire Loop
1) connected in series
2) no supervision ( a short will not register)
3) when one opens (device) the current flow stops

Two Wire w/ ELR (Resistor)
1) connected in series
2) responds to shorts
ELR at end of loop (low to medium security)

Four Wire Loop
1) Hi/Lo Loop
2) Two Loops
3) Supervises both shorts and opens
4) Higher Security

Four Wire ULC
1) high level of security
2) Has a high/lo loop
3) contacts are SPDT (Single Pole Double Throw)

Zones of Security

There are four different types of zones:

1) Delayed Zone - causes a delay to arm the system or to disarm.

2) Instant Zone - causes an alarm when tripped.

3) Delayed Instant Zone - used with other interior detectors, helps with false alarms.

4) 24 Hour zone - armed 24 hours a day, and can utilize panic button.

Security Devices

Magnetic Contacts: are either mounted on the surface or drilled into the frame of an object

Reed Switches: are fragile low current devices that need critical alignment.

PIR Detector: Passive Infrared Detectors react to ambient IR level of the room. The heart of the device is a pyroelectric element. It is unable to focus on objects and is only useful up to 30m.

Microwave/ Ultrasonic: Actively emits radiation. This device can bounce off objects without changing frequency. It is unaffected by ambient temperatures but moving objects can cause a frequency shift.

Photoelectric Beam Detectors: This device works up to two (2) kilometers. A long range device that is also not affected by ambient temperatures. This is a supervised device that requires extra time for installation.

Control Panel: Reacts to changes in current. Panels with four, eight, and sixteen zones are common.