This document provides technical information for the installation of refrigeration, air conditioning and heat pump equipment containing flammable refrigerants, in particular from class A3, complementing existing standards. The term "refrigerating system" used in this document includes air conditioners and heat pumps. Refrigerants from toxicity class B are excluded from this scope. This document includes risk mitigation measures not yet addressed in existing standards for specific refrigerant classes, or not fully reflecting the state of the art, and establishes complementary technical specifications related to the installation of equipment. The following aspects are considered: - explosive atmosphere workplace and equipment; NOTE Further information can be found in Directive 99/92/EC (ATEX Workplace Directive) and Directive 2014/34/EU (ATEX Equipment Directive). - design and structural specifications for the installation site; - marking and labelling of equipment parts and installation site; - good practice for installing equipment, including tools and personal protection; - risk mitigation methods and related refrigerant charge limits; - risk assessments; - competence of personnel; - safety testing of systems and equipment.