This document specifies general requirements for the construction, testing and performance of electrically operated apparatus for the detection of flammable gases, designed for continuous operation in a fixed installation in household premises. The apparatus can be mains or battery powered. Additional requirements for apparatus to be used in recreational vehicles and similar premises are specified in EN 50194-2. NOTE For caravan holiday homes EN 50194-1 applies. This document specifies four types of apparatus to operate in the event of an escape of town gas, natural gas or liquefied petroleum gas (LPG), Hydrogen and flammable refrigerant gases: Type A apparatus provides a visual and audible alarm and an executive action in the form of an output signal that can actuate directly or indirectly a shut-off device and/or other ancillary device in the event of an escape of town gas, natural gas (LNG) liquefied petroleum gas (LPG) and Hydrogen gases; Type B apparatus Same as Type A but provides a visual and audible alarm only; Type C apparatus provides a visual and audible alarm and an executive action in the form of an output signal that can actuate directly or indirectly a shut-off device and/or other ancillary device in the event of an escape of flammable refrigerant gas A2L, A2 or A3 as classified in other International Standards, e.g. ISO 817; Type D apparatus intended to be installed where there can be a source of danger to the public, designed for continuous operation in fixed installations in non-classified explosive atmosphere premises (where the requirements for electrical Ex-safety are not requested). Intended for any flammable gases. Typically Type D apparatus are available with analogue or digital output, in the form of detection system, system regularly maintained by competent persons and/or with protection IP44 or higher. For type D equipment, EN 60079-29-1 is applied. See Annex C for further clarification on the apparatus types and their application. NOTE Apparatus complying with this document is not considered suitable for installation in potentially explosive atmospheres, in which case the EN 60079 series applies. NOTE Apparatus complying with EN 60079-29-1 will not necessarily comply with this document. This document does not apply to any of the following: apparatus intended for the detection of dusts or mists in air; scientific or laboratory-based apparatus used only for analysis or measurement; apparatus used exclusively for process measurement purposes; apparatus for medical purposes; apparatus used for breath alcohol measurement; apparatus intended for the direct measurement of automotive exhaust gases; apparatus intended for use in industrial environments.