The mains RCD is usually incorporated within the main distribution board but may be found as a free-standing unit fed from the distribution board. These are commonly used almost anywhere, from domestic to industrial and. A distribution box uses MCBs, RCDs, and busbars to protect circuits, prevent shocks, and ensure safe power distribution in homes and buildings. You use a distribution box to divide electrical power into smaller circuits. In simple terms, it distributes electricity safely. A residual-current device (RCD), residual-current circuit breaker (RCCB) or ground fault circuit interrupter (GFCI) is an electrical safety device, more specifically a form of Earth-leakage circuit breaker, that interrupts an electrical circuit when the current passing through line and neutral. Main Distribution Board (MDB) is also known as Fuse board or consumer unit where the main protective and isolation devices are installed to provide electricity in a safe range to the connected electrical appliances. Related Wiring Tutorials: How To Wire Switches in Parallel? The Distribution Board. It is an electrical protective device that protects electrical circuits and devices from some electrical faults such as leakage faults, electrical shock, current unbalance due to equipment failure, etc. Also known as a Residual Current Breaker (RCB) or Residual Current Circuit Breaker.