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Fire Alarm -- Description

Email, Big Voice, Text, Mass Phone, Twitter, Radio, Television
Mass Notification Systems are not specific equipment, they're the method used to get emergency messages out to as many people as possible.
Douglas Krantz -- Fire Alarm Engineering Technician, Electronic Designer, Electronic Technician, Writer

What is Mass Notification?

By Douglas Krantz

When a disaster or emergency strikes, and everyone in the area is to take action now, a Mass Notification System is a Call-to-Action.

Call To Action

A Fire Alarm System is a type of Mass Notification System; when there is a fire, it calls the evacuation of a building.

On the other hand, a Mass Notification System calls people to action with any impending danger - fire, dangerous weather, terrorist, tsunami, explosion, or even invasion. In an emergency, it's a means of giving of instructions to a large number of people, all at once.

Area Wide

A Mass Notification System covers a larger geographical area than a building's fire alarm system, like:
  • A college campus
  • A military base
  • An open air arena
  • A hospital complex
  • A community


Not just turning on the fire horns like with a fire alarm system, It gives more instructions. it tells people:
  • A tornado is coming - move away from windows
  • There is a bomb - get out of the building
  • A gunman is on the loose - lock yourself in
  • A chemical plant is on fire - leave the area
In addition to the general instructions, each type of facility - military base, college campus, large hospital, open air arena - has a customized set of instructions.

A hospital, for example, would include in its customized messages:
  • Code Blue - send help, someone's heart has stopped
  • Code Green - get security, a patient has become violent
  • Code Grey - be on the lookout, a patient is somewhere wandering the halls
  • Code Red - protect the patients, there's a fire in the hospital
In the above hospital example, pocket pagers and overhead paging systems reach everyone in the hospital. Just to make sure the security department sends out more detailed directions.

Overcoming Communication Problems

The general public, however, isn't so easy to reach.

Single communication systems only pass instructions to a few people at time:
  • Not everyone hears the overhead paging speakers
  • Not everyone has a pocket pager
  • Not everyone carries a cell phone
  • Not everyone is always listening to the radio or watching television
  • Not everyone surfs the internet
  • Not everyone hears the fire alarm system
  • Not everyone hears the outside civil defense sirens
By themselves, none of these systems can furnish emergency instructions to large numbers of people, but each of these systems does reach some people:
  • The overhead paging speakers reach people in offices or warehouses
  • Cell phones (text messaging, voice messaging, twitter, etc.) reach people chatting with friends
  • Radio and lit signs reach many who are in a car
  • Television reaches those being entertained at home
  • Email and override messages on the internet reach people working in offices
  • The fire alarm system, using voice messages, reaches people who are asleep
  • Outside big-voice speakers (like civil defense sirens, only using voice announcements) reach people outdoors
By using all of these methods at once to get the message across, most people in the general public will receive their emergency instructions.

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Mass Notification

A Mass Notification System is flexible; it covers any disaster and instructs people about what to do. To get an emergency message to almost everyone at the same time, it is a coordination of many individual communication systems.

Like a fire alarm system, a Mass Notification System gets people's attention. However, unlike a fire alarm system, which only notifies the people of a fire inside a single building, a Mass Notification System reaches people in a community or set of buildings, both inside and out.

A Mass Notification System calls everyone to action.


Douglas Krantz

Describing How It Works

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Electrical Flow

On this website, most references to electrical flow are to the movement of electrons.

Here, electron movement is generally used because it is the electrons that are actually moving. To explain the effects of magnetic forces, the movement of electrons is best.

Conventional current flow, positive charges that appear to be moving in the circuit, will be specified when it is used. The positive electrical forces are not actually moving -- as the electrons are coming and going on an atom, the electrical forces are just loosing or gaining strength. The forces appear to be moving from one atom to the next, but the percieved movement is actually just a result of electron movement. This perceived movement is traveling at a consistent speed, usually around two-thirds the speed of light. To explain the effects of electrostatic forces, the movement of positive charges (conventional current) is best.

See the explanation on which way electricity flows at