Intumescent gaskets are essential in metal or plastic boxes wherecables pass back through a wall. Gaskets must be fitted to all dry lining boxes in partition walls. Without these gaskets fire can spread into the partition within 4-5 minutes. Where cables run through back to back boxes in brick or block walls, flames can pass through within 6 minutes, resulting in a wall or partition only 6 minutes of fire integrity.
Gaskets for use inside metal or plastic boxes are made to the size of the box and come with self-adhesive fixing on the back. Once the backing paper has been peeled off the fixing strip, the gasket can be adhered to the inside of the box. Holes can be cut into the gasket with a sharp knife to receive cables, or the gasket can be cut to fit the back of the box if cables are already fitted. Dry lining boxes in walls have two pads per box, made to size and adhered top and bottom.
Plasterboard ceiling rose boxes can be protected by means of an intumescent cover which folds up and is passed through the hole in the ceiling. A hole is then cut in the cover to receive the cables, which are then pulled through the cover, box and ceiling before connecting the ceiling rose. Ceiling rose gaskets to fit over the ceiling rose or hook plate should be fitted where more than two cables pass through the ceiling. A hole is made in the gasket through which the cables are passed. The backing paper of the self adhesive fixing strip is then peeled off and the gasket is adhered to the ceiling. The pendant or light fitting can then be fitted.