Wires + Breakers

• Live wire = brown = current IN at a high voltage
• Neutral wire = blue = Current OUT at a lower voltage
• Earth = yellow + green = safety wire (carries I safely into ground if a fault occurs in a metal-framed appliance- e.g. kettle)
• CURRENT = key word
• Safety features = Earth wire, Fuse, MCB, RCCB
• Fuse = a plastic tube containing a thin piece of metal; attached to live wire; Fuse is designed to break live wire if overload of current
• Fuse adv = cheap, small so can be used in all appliances
• Fuse dis = not reusable, takes time to replace, they melt and break - do not work quickly, appliance could already have had problems)
• MCB (Miniature circuit breaker) = always on live wire, uses an electromagnet (magnet gets strong when the current increases, breaking circuit if too much)
• MCB adv = works quickly (don't have to wait for it to melt), easy to reset - just press a switch -, reliable
• MCB dis = very large (can't use everywhere), expensive( have to pay to fit also)
• RCCB = (residual current circuit breaker/device)
• RCCB = left over I circuit breaker, measures I in and out (should be equal, if not breaks the circuit)
• What is the relationship between I out and I in?

  Should be equal
• RCCB = only safety feature that works if I breaks
• RCCB adv = protects user, works very quickly, very sensitive, can be reset
• fuse = fault leads to current overload
• MCB = automatically switches off after a fault
• RCCB = protect user by meauring imbalances in current in and out (which should be equal)
• MCB = protect the circuit
• RCCB = protect the user
• RCCB = most sensitive -> fastest
• earth = metal-framed appliance
• RCCB = mentioning of wires rather than current (e.g. live wire = broke)
• MCB = current
• fuse = current