Fuses and Fuse Boxes - Car Builder Solutions We sell a wide range of fuses, relays and fuse boxes from a single fuse to a complete car wiring module. Fuse types we stock are Mini, Standard and Maxi Blade, Ceramic, Glass and MIDIVAL. Our modular fuse and relay box system gives great possibility to find the right solution for any need. What is the purpose of fuse and relay box in cars? - Quora Sep 25, 2017The fuse used in the car box is to limit the current and prevent the fire. A relay is a switching device that uses a small electrical current to control a much larger current in a second circuit. In other words, a relay routes power to a circuit or component when it is turned on.