Megger det14c clamp on earth resistance tester megger 1000 761 the megger det14c is an advanced clamp on ground resistance tester that sets new standards in terms of access performance features simplicity of operation and safety these units are designed with flat core ends to prevent dirt build up ensuring measurement integrity and improved reliability over products with interlocking teeth other enhancements include safety to cat iv 600 v a built in filter function for electrically noi