Over in Part 5 BS7671 we have Chapter 53 – Protection, isolation, switching, control and monitoring.
A good way to remember this very important Chapter during your 17th Edition exam is to just think “turning stuff off”.
531: Fault protection (ADS).
It tells you what devices you should be using for turning things off during a fault and that fuses and circuit breakers must meet the maximum disconnection times stated in Chapter 41. In other words that they should not exceed their Max Zs (80% of measured).
RCDs have quite a large section here in Chapter 53 and it goes into great detail as far as the specification and the requirements of RCD fault protection is required.
533: Overload protection
Covers the requirements of fuses and circuit breakers used for overload protection.
534 and 535: Devices for overvoltage and undervoltage protection
Equipment and procedures for dealing with electromagnetic interference and voltage surges, undervoltage and loss of voltage.
537: Isolation and Switching
Devices for isolation, both for electrical and general maintenance, emergency switching and normal everyday functional switching.
538: Monitoring
If for any reason something cannot be switched off especially during a fault or overload then the circuit must be monitored. Here is where you’ll find guidance on the devices to use.