4.20.1 All electrical cables shall be flexible, flame-retardant, standard sheath wall and LSZH types complying with EN 50264. The flexibility of cable shall be class 5. The cables shall be adequately rated and protected for their intended duties and loading requirements. The cable size selection and other electrical design shallcomply with BS 7671, Requirements for electrical installation - IEE Wiring Regulation 17th edition. Cable specification shall be submitted to the Engineer for approval.