In the UK, what type of installation requires a fireman's switch?

Neon lighting runs at a high voltage, typically above 1000 Volts. A fireman's switch protects a fireman from receiving a shock when a water jet is sprayed onto the installation. The switches are red, and mounted in a conspicuous position. (This is specified by IEE Regulations (Europe), SANS (South Africa), UK Electricity regulations and many Asian countries. I am unable to confirm other countries' requirements, so feel free to let me know.)