the-Regs : BS7671 18th Edition Online Training
BS 7671: 18th Edition Wiring Regulations – Study when you want and pass your exam when you're ready…
Just a quick post about a question that is often asked… “Do I need to earth the metal back box for a socket?” A metal back box for a socket would be classed as an exposed-conductive part and as such it needs to be earthed. If the back box has a fixed lug on one … Read more
The maximum disconnection times for a TT system is 0.2 seconds for final circuits up to and including 32A (Table 41.1) and for distribution circuits or circuits greater than 32A it’s 1 second (411.3.2.4). The problem is that with TT systems the external loop impedance value (Ze) will be too high to achieve these 0.2 … Read more
Prospective Fault Current (Ipf) is the general term used for the highest amount of current that will flow under fault conditions. On a single phase installation fault conditions can either be Prospective Earth Fault Current (PEFC) Line to Earth or Prospective Short Circuit Current (PSSC) Line to Neutral. Whichever one is the highest would be … Read more