The manual call point is the oldest part of a modern fire alarm system and still the fastest. A person who has seen a fire can raise the whole building in one second, which no detector can promise. Everything about the way they are sited follows from that: on the escape routes, at the exits, at a height somebody can reach in a hurry, and visible without looking for them.
Where they go
On escape routes, at every storey exit and at every final exit to open air, so that nobody leaving the building passes a point where they could have raised the alarm and did not. The spacing rule is expressed as a maximum travel distance to the nearest point rather than a grid, with a shorter distance where occupants are less mobile or where a fire could develop fast.
Height and reach
Points are mounted at a height chosen so an adult can operate one without stretching or crouching, and the same height throughout a building so people find them by habit rather than by searching. Where wheelchair users need to reach them, a lower mounting height is appropriate and should be applied consistently rather than to a single token point.
Break glass and resettable elements
Modern points use a resettable plastic element rather than real glass, operated by pressing and reset with a key. They are still called break glass units and the sign above still says so. Some carry a hinged cover to reduce malicious operation, which is a design decision with a real cost: a cover adds a step for somebody in a panic, so it belongs where misuse is a demonstrated problem rather than everywhere by default.
The sign
A call point should carry a sign identifying it as a fire alarm call point, in the safety sign format used for fire equipment, so that it reads as a fire device at a glance and in poor light. Signage on fire equipment follows the same colour and shape conventions as the rest of the safety signage in the building, which is the point: nobody should have to read the words to know what it is.
Questions people ask about fire alarm call point
How far apart should call points be?
The rule is maximum travel distance to the nearest point rather than a fixed spacing, and the distance is shorter where occupants are less mobile or the fire risk is higher. Your system design should state the figure it was designed to.
Do call points need a sign above them?
They should be identified so they read as fire equipment at a glance. Safety signage for fire equipment follows a standard format across the building rather than being invented per device.
Should call points have protective covers?
Only where malicious operation is a real, recorded problem. A cover adds a step for somebody raising a genuine alarm, so fitting them everywhere as a default is a trade against the thing the device exists for.