Electrical warning installations and status sensors, photoelectric and infrared barriers, ultrasonic and vibrational emitters and receivers, electrical signal exchanges, fire alarms, burglar alarms, alarm and signalling units; combustion gas, gas, smoke, aerosol, flame and temperature detectors; equipment for protection against burglary, breaking-in and assault; access control units; signal transmission and display equipment, fire-fighting equipment, electronic valves, indicator glow lamps, over-voltage suppressors; computer software