The thermostat must be protected wth 16 A circuit breaker (fuse) on power lead. Where the circuit breaker is mounted in Ex classified zones, ATEX certified circuit breakers must be used.Electrical connection to the heater must be executed via a circuit breaker, max. 16 A and terminals mounted inside an enclosure.The ambient air thermostat Series TEF502392xx must be used as ambient air sensing working thermostat mounted in ATEX certified Ex e enclosures or enclosures for safe areas.