When cable trays pass through walls or floors, seal openings using fire-rated penetration sealing materials. Do not modify or damage the tray coating or structure during use. Whether you're installing security cameras, setting up a home network, or extending ethernet connectivity to an outdoor space, running cable through an exterior wall is one of the most common DIY projects homeowners face. However, if the cable tray does pass through a fire separation, then the tray must be protected with an intumescent coating for a sufficient. Cable trays seemed to run through fire rated barriers with reckless abandon; the holes created by passing the tray through the wall or floor varying in size and shape.