Level of interior fire protection, fire resistance duration of at least 30/90 min. Boxes other than electrical boxes, protected with membrane firestop. The International Building Code, which is adopted in most US jurisdictions, requires that all recessed fixtures be installed such that the fire resistance rating of the wall not be reduced. Many red tags are issued by city inspectors for electrical boxes incorrectly installed in fire rated walls, floors or. 3M™ Fire Barrier Electrical Box Inserts are a flexible, one-piece fire-rated intumescent insert used to protect electrical boxes by adhering to the inside the box. 3M™ Fire. With the introduction of the 15th Edition of the IEE Wiring Regulations in 1981 the UK aligned the requirements of the regulations with the International Electrotechnical Commission (IEC) worldwide electrical installation standard IEC 60364.