What Is a Control Box? A control box is a centralized hub that helps manage, monitor, and protect electrical systems. This setup makes it easier to control equipment. The 6 Way Universal Fuse Relay Block Kit is 6 slots relay panel design, 5 slots for 5-pin Bosch style relays, and 1 slot for RTT7121 4-pin relay. Each slot is precisely. Distribution Box: Handles main supply voltage (220V–690V) with current ranging from tens to hundreds of amps. It brings together switches, relays, circuit breakers, and other devices in one safe location.