This standard is besides to reactor protection systems, also applicable to temporatory installations which are part of the protection system. Section 2 is intended particularly for the cabling of the protection system. Its object is to identify a certain number of possible causes of failures and to lay down, taking these causes into consideration, a set of basic rules to be followed when desgning a protection system in order to ensure that its purpose is fulfilled in the best possible way (these rules apply to the protection system as a whole), as well as to give requirements to be fulfilled for cabling separation within a reactor protection system.