Space-saving surge arrester module with LifeCheck for protecting up to four single earth-potential-free wires with a common reference potential of intrinsically safe measuring circuits, meets the requirements of FISCO. ATEX. Insulation strength > 500 V wire-earth. LifeCheck detects thermal or electrical overload conditions after which the arrester must be replaced. The indication is contactless using DEHNrecord LC / SCM / MCM.