How to Wire a Fuse Box | DoItYourself Voltage Meter. The fuse box in your home is there for protection against power surges and potentially life threatening fires. When there is an overload in the system, caused by a short or some other electrical power surge, the fuse will blow instead of letting the power flow continue on to an electrical device. B+ terminal repair - main fuse box - Volvo Forums Jan 31, 2016Originally four wires are wraped together as a single cable to carry the current to the main fuse box. These wires are an integral part of the vehicule harness. Opening the wiring harness to replace them isn't partical.