G
PHYSICS
G
PHYSICS
G08
SIGNALLING
G08
SIGNALLING
G08B
SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
G08B
SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
21/00
Alarms responsive to a single specified undesired or abnormal condition and not otherwise provided for
21/00
Alarms responsive to a single specified undesired or abnormal condition and not otherwise provided for