Metacaulk® Cover Guard™ is a single component fire rated gasket for use with electrical boxes when addressing steel electrical box penetrations in fire rated assemblies (the "24 inch rule"). It is mounted on the inside of the cover plate and installed at the same time as the cover plate, covering the opening and providing the necessary fire protection. When exposed to heat, Metacaulk® Cover Guard's highly intumescent nature causes it to expand forming a char that will seal off the opening and prevent the spread of flames and limit the temperature rise on the unexposed surfaces. Metacaulk® Cover Guard is applied by hand, does not take up volume in the electrical box and is a labor saving replacement for putty pads in normal applications. U.S. Patent No. 6,207,085; 6,252,167 & 7,348,484.
Metacaulk® Cover Guard is used when electrical boxes are installed in rated walls facing opposite directions and horizontally separated by less than 24". Metacaulk® Cover Guard can also be used as a solution for standard electrical boxes when the 100 square inch rule is violated. Metacaulk® Cover Guard is UL tested and can be used with both metal and plastic cover plates. Tested conditions for one and two hours.