Manual call points (MCP’s) are the red break-glass units that are installed on the walls in various locations around the building including near exits and stairwells. By understanding how these work and what will happen when one is activated, building managers and occupants will be able to deal with the situation in the most effective manner.
What a Call Point Actually Is
A manual call point (MCP) is a simple device that forms part of the overall fire alarm circuit. It is typically a weak point in the overall circuit and is designed to be triggered by a person in the event of an emergency. The typical form of a manual call point is a red push button, often fitted to the walls near exits, or alternatively in stairwells. These units are typically mounted at a height of around 1.2m to 1.4m above floor level to ensure that they are easily accessible to all people.
The Physical Action
When the frangible part of a Manual Call Point is pushed or struck, it breaks or flexes allowing the two contacts within the unit to close. This allows a signal to be sent down the fire alarm cable to the fire alarm control panel. Many Manual Call Points are now fitted with a resettable insert, which allows the unit to be reset after activation for testing purposes, or after a real alarm activation, without the need for replacing the entire unit.
What Happens at the Control Panel
The panel receives the signal in seconds, displaying a zone indication or even showing the exact location of the call point that has been activated. For manual call points installed as part of an addressable fire alarm system, the panel will display the specific device name or location of the call point that has been pressed. The panel will then activate the sounder circuit sending a continuous tone to all audible sounders within the building.
What Occupants Should Do
As the sound of the continuous tone of the evacuation signal is heard by all the occupants of the building, they should immediately proceed to leave the building by the nearest safe exit. No attempt should be made to investigate the cause of the activation of the fire alarm system. The panel log will contain details of the time and point of activation of the fire alarm system. This information will be passed to the Fire Service and will also be used in any post-incident investigation.
Keeping Call Points Accessible
Workplace fire safety responsibilities also include ensuring that your manual call points are always unobstructed and are of a suitable height. Many times during installations and servicing of fire alarms, ISE Fire engineers come across call points that have been painted, incorporated into new partitions or even installed at the wrong height. This can seriously affect the time taken to activate a call point in the event of an emergency. It is recommended that manual call points are installed between 1.2m and 1.4m from the floor to enable everyone to easily and clearly break the glass in the event of an emergency.
A simple device but a vital one that only works when it is maintained correctly, kept clear and tested regularly.
