FR-4 Insulating Boards are used for isolating live equipment on angle iron crossarms, such as when replacing fuse links or surge arresters, to shield adjacent phases and limit human activity, thereby enhancing the insulation level between phases. 2. These electrical insulating boards possess high insulation properties and can be directly contacted with live parts up to 35 kV, serving as temporary barriers. Insulating plates can also be placed between the moving and stationary contacts of a drawn-out switch to prevent accidental energization after the switch falls. When installing or removing the insulating plates, maintain a safe distance from the live parts (in accordance with safety regulations) or use insulated tools for the operation. 3. In electrical construction work, they are used for isolating and protecting transformers, section switches, and other equipment.