About Intumescent Fire Protection Gaskets
Where socket outlets or switches are back to back in fire walls with cable or conduit passing through walls, gaskets must be fitted inside these boxes to stop the passage of fire.
In addition all boxes in plasterboard partitions need to have gaskets fitted.
Where steel conduits pass through firewalls or floors, it is essential to terminate each side of the wall or floor slab with a BESA box or universal conduit box. The intumescent gaskets fit into the back of the box, stopping the passage of fire and smoke from one compartment to the other