What fuse rating is typically used in a fused connection unit to protect a fused spur off a ring circuit?

• A. 16A
• B. 45A
• C. 32A
• D. 63A

Answer: (C)

When protecting a fused spur off a ring final circuit, the protection shown by the fuse in the fused connection unit works in tandem with the ring’s own protective device. The idea is to have a local protective device that limits damage to the spur wiring and any appliance fed from it, while still relying on the ring circuit’s protection to guard the rest of the circuit. In many standard installations, the ring final circuit is protected by a 32A device. Using a fuse rating in the fused connection unit that matches this 32A protection ensures the spur cannot overload beyond what the ring circuit can safely carry, and it keeps the protection scheme consistent and predictable. Smaller fuse ratings would overly restrict the spur or cause nuisance tripping, while much larger ratings would undermine the protection of the spur wiring. So, 32A is a typical choice for the fuse in a fused connection unit protecting a fused spur off a ring circuit.