This design note adopts a 300 mm horizontal air-gap separation between primary and secondary life-safety trays on roofs, based on these regulatory requirements and established UK guidance. BS 7671:2018 +A2:2022 states: “Circuits of safety services shall be independent of other. A maximum of ten numbers of 25mm diameter service conduits for electrical and communication cables serving the SS, and for electrical and communication services which are located on external face of SS wall, are allowed to be embedded in the SS walls. Both ends of these concealed conduits shall be. All service conduits shall not penetrate through the walls and slabs of the HS. Drilling through the membrane creates potential leak points and can jeopardize roof warranty. Cable tray systems are often used for cable management in commercial projects to support insulated electric cables on flat roofs. This document outlines the key requirements for cable tray layout, installation, and fireproofing in industrial and commercial environments.
[PDF Version]