Fire

Open areas under flat horizontal ceilings

Maximum area covered by 1 heat detector: Heat 50m² Smoke 100m²
The maximum distance between any point of an area to the detector, should be, 5.3m for Heat detectors, 7.5m for Smoke detectors

Minimum distance between detector (other than beam detectors) and wall or partition should be 500mm
Maximum spacing between detectors is reduced when obstructions are present

Corridors
Detectors in corridors may generally be spaced more widely.

This is NOT applicable to life safety applications unless all adjoining rooms have smoke detection.
Corridors greater than 5 metres wide treat as for flat horizontal ceilings

Detectors may be placed at horizontal distances extended up to 50% of the difference between the actual corridor width and 5 metres. E.g. for a corridor with a width of say 1.5m, the maximum distance from a detector can be increased,
for a smoke detector by:- (5m - 1.5m)/2 = 1.75m + 7.5m = 9.25
for a heat detector by:- (5m - 1.5m)/2 = 1.75m + 5.3m = 7.05

Pitched roofs
A row of sensors should be installed along the apex of any pitched roof or "north-light" roof. Smoke detectors should not be more than 600mm, and 150mm from the apex of the roof, 150mm max for heat detectors. Horizontal spacing between sensors may be extended when used under pitched roofs, by 1% per degree of slope, to a maximum increase of 25%.

Heights
Maximum heights of detectors are dependant on the fire brigade response available.

Detector/Sensor type	General Applications (m)	Automatic link to a manned centre. Fire Brigade response is normally within 5 minutes. (m)
Smoke	10.5	15.0
Heat Grade 1	9.0	13.5
Heat Grade 1	7.5	12.0
Heat High Temp	6.0	10.5
Beam	25	40

String Of Beam Detectors
As with point detectors, a beam detector must be sited in the apex of a pitched roof.

	Minimum (m)	Maximum (m)
Height of optical beam of floor	2.7	25*
Optical beam length	5	100
Distance of optical beam from a flat ceiling or apex	0.3	0.6
Horizontal distance between optical beams measured at right angles to the beam	-	14
Horizontal distance between optical beams and an adjacent wall or partition	See Notes	8

*The height may be increased to 40m provided that the general height to which the combustible are stored in the building does not exceed 5m and that the fire brigade can attend within 5 minutes.

Note: Generally the beam should not pass less than 500mm to a wall or partition, and not closer than 600mm to an obstruction. Where the beam detector is mounted in the apex of a pitched or 'north-light' roof the horizontal distance can be increased by 1% for each degree of slope up to a minimum of 25% (e.g. 20" slope of roof 20% of 7.5m = 1.5m increase).