A Guide to Screw-In Fuses and How They Work - The Spruce The Fuse Box. A fuse box has a series of threaded sockets into which the fuses are screwed in like light bulbs. Each circuit in the home is protected by a fuse, and each fuse must be the correct type and appropriately rated for its circuit. Using the wrong type of fuse for Author: Bob Formisano How to Replace the Fuse Holder in a Fuse Box | eHow Replace the fuse with a new fuse and restore the main power. Test the light, or outlet connected to the new socket to ensure proper operation. If the fuse pops or the problem persists, consult an electrician to ensure proper repairs are made to maintain safety.