Cartridge Fuse

• Usually found in plugs
• 45A >13kW
• 30A > 7kW
• 20A – for storage and water heater circuits
• 15A < 3kw for single appliances circuit
• 13A between 700W – 3kW
• 5A for lighting circuit (MAX load is 1200W or 12x100W lamps)
• 3A < 700W (table lamps and alarm clock)

High Breaking/Rupture Capacity Fuse (HBC)

• link can blow without the fuse itself being destroyed

Miniature Circuit Breaker (MCB)

• opening as a result of the increased heat or magnetism
• Situated in the Consumer Unit
• Trips out when fault occurs
• Protects against overload

Residual Current Device (RCD)

• senses an imbalance of current between the phase and neutral
• Protects against Earth faults
• Operate when detecting the fault above 30mA

Residual Current Breaker with Overload (RCBO)

• Combination of MCB and RCD
• Recommended for commercial installations
• Protects single circuits (ring with lots of computers in use)

Rewireable Fuse

• Not used on new installations because wrong wire can be used

Suppliers Main Service Fuse

• supplier’s cut out
• part of the Supply Company’s Head
• Sealed and can be served only by electricity supplier
• MIN 750mm below roads (MIN 450 if below open grounds) – underground supply cables

Customers Consumer Unit (CCU)

• 25mm2 – cross sectional area cable between Company’s Head and CCU for live and neutral
• Contains the main double-pole switch
• Bus bar?????????????
• Circuit Protection Conductors (CPC) – where “earth” conductors are terminated (Earthing Bar)

Main Earth Terminal

• 16mm² earthing conductor from earthing bar in CCU
• 16mm² cable to the service head or outer casing of the supply cable  - in case of underground supply
• To an earth electrode (main earthing conductor) – in case of overhead supply