If you have electrical devices fitted in a compartment containing gas or petrol there's a danger of the flammable gases being ignited by hot components or electrical discharges and causing a fire or an explosion. To minimise the risk of this happening the electrical devices must be ignition-protected to meet BS EN 28846.
Boats built before 16 June 1998 are exempt from this requirement if it wouldn't be practical to comply, e.g. if the relevant component is not readily available. [3.7]