Mark O'Driscoll - Electricians | Electrical Services | Warminster, Salisbury, Hindon, Tisbury, Shaftesbury.

AICO Expert InstallerMark O’Driscoll Electrical Contracting has achieved a registered AICO Expert Installer Status. Let us help you design and installer your Fire Alarm and smoke detection installations to achieve a compliant system.


Which alarm sensor goes where?

Fire alarms have different sensors to detect different fire types. Some alarm sensors react to heat and some to the physical smoke created by a fire. By fitting the right type of alarm sensor you will avoid nuisance alarms and get the best protection.

Here’s our guide to choosing the right alarm for each area within a property. The two houses below show rooms that are colour coded to show which sensor types are best suited to each area of a typical property. The house on the left shows a layout using multi-sensor fire alarms and the house on the right shows single sensor alarms.

Layout using single sensor fire alarms

Single Sensor Layout.

Optical Sensors

Alarms containing optical sensors use an infra-red beam to detect smoke. They detect smoke from slow, smouldering fires such as electrical fires and are less prone to false alarms from cooking fumes if fitted in the hallway next to kitchens.

Fit Optical Alarms in: Hallway, Landing, Living Room, Dining Room


Heat Sensors

Alarms containing heat sensors only detect changes in temperature using a thermistor. The trigger level is set to 58°C degrees. Ideal for kitchens as they won’t nuisance alarm from cooking fumes but should not be used in other areas of a property as they will not provide the speed of response required – smoke alarms should be used instead, see above for guidance.

Fit Heat Alarms in: Kitchen, Garage

Multi Sensor Layout

Multi Sensor Layout.


Contains optical and heat sensor to detect both smoke and heat, so responds to all fire types from fast flaming to slow smouldering providing the best fire reponse. As the alarm also intelligently monitors both sensors, the risk of nuisance alarms is virtually eliminated.

Fit Multi-Sensor Alarms in: Hallway, Landing, Living Room, Dining Room, Bedrooms