These specialized trays are designed using non-combustible materials, often rated according to international standards such as UL 94 and IEC 60332. Install fire barriers within the tray to isolate different fire zones. Do not modify or damage the. Electrical cable tray wall penetration firestopping Scope: Firestopping for busway, cable trays, cables, and trunking passing through walls in enclosed electrical installations. Where cables pass through shafts, walls, slabs, or enter electrical panels or cabinets, openings shall be tightly sealed. Cablofil cable tray is the preferred choice for the cable containment of low and high voltage electric cables where fire resistance is crucial - this includes cable basket tray systems for Prysmian FP (FP400 and FP600) and Draka Firetuf type cables. The following charts give the number of 3M pillows needed to completely firestop an opening that cable tray passes through.