Where cables pass through shafts, walls, slabs, or enter electrical panels or cabinets, openings shall be tightly sealed with firestopping materials in accordance with design requirements. Scope: Firestopping for busway, cable trays, cables, and trunking passing through walls in enclosed electrical installations. In other words, the cable tray manufacturer did not go to UL or ETL and say “test this tray penetration for 2 hours, make the hole this size, and use these pillows, compressed this. Our insurance company is requiring us to fire stop around cable trays where they penetrate walls. Most places look like it was never done in any manner and others look like it may have fallen away if ever there. We are closing gaps with drywall, fireproof rock wool and red caulk,. Tedious job, as. Tray fill limits must be calculated properly. Mesh trays reduce installation time while supporting compliance. Understanding NEC Article 392: Cable Tray Systems The National Electrical Code (NEC) Article. RECOMENDATIONS BE APPROX. 6" LARGER THAN THE OUTSIDE DIM. OF CABLE TRAY FIRE SEALANT BAGS (SEE NOTE #1) BAGS SHALL BE: GRACE CONSTRUCTION PRODUCTS KBS SEALBAGS OR 3M FIRE BARRIER PILLOWS. INSTALL BAGS PER MANUFACTURERS INSTRUCTIONS TO ACHIEVE UL CLASSIFIED FIRE RATING EQUAL TO OR GREATER THAN FIRE. 3M Fire Barrier Moldable Putty+ is a one-part, halogen-free product designed to firestop electrical outlet boxes and a wide variety of through-penetrations including cable, conduit, insulated pipe and metal pipe, which penetrate fire-rated construction. This organic/inorganic elastomeric sheet is.