Electric Shocks

How an electric shock occurs… Current travels through conductors within a closed circuit. The conductors could be made of copper such as in a cable, other metals, water or in the worst case the conductor can become the human body. An electric shock occurs when a person becomes part of a circuit, with current entering … Read more

Earth Fault Loop Impedance (Zs)

The earth fault loop impedance (Zs) directly effects the amount of current that flows under earth fault conditions. (Ipf = V / Zs). As I’ve mentioned in a previous post (see here) fuses and circuit breakers need a certain amount of current in order to meet their maximum disconnection times. ie a 20A type B circuit … Read more

Supplementary Bonding Bathroom Radiators?

This may not be an issue in newer bathrooms that comply with current editions of BS7671 as supplementary bonding in bathrooms may be omitted when regulations 701.415.4.5 (iv), (v) and (vi) are met. However, supplementary bonding the radiator has always been a grey area especially in older bathrooms because the radiator may or may not be an extraneous-conductive part. … Read more

Methods of Fault Protection

The17th Edition of the Wiring Regulations gives us methods of fault protection within Part 4 Chapter 41 BS 7671. But firstly what is Fault Protection? Part 2 of BS 7671 Says… “Protection against electric shock under single fault conditions” In plain language this means that fault protection provides us with protection against receiving an electric shock from … Read more

Ten 17th Edition Regulations at Christmas

It’s the festive season ‘again’ and just for a bit of fun here’s… “Ten Wiring Regulations That Apply to Christmas” 314.1 Every installation shall be divided into circuits, as necessary to: (iii) take account of the hazards that may arise from the failure of a single circuit such as a lighting circuit. 414.1.1 Protection by … Read more