18th Edition and Three Often Used Calculations

Let’s take a look at what are possibly the three most used calculations within the 18th Edition Wiring Regulations for electrical installations. Calculation Voltage Drop Calculating the cross-sectional area of protective conductors Tabulated current carrying capacity of conductors ‘It’ 1. Calculating voltage drop… You won’t find this formula anywhere in BS7671:2018 as this is another … Read more

Single and 3-Phase Electricity

One of the main reasons for using an alternating current a.c. supply is that we can easily change the voltage levels up or down by using a transformer which would be more difficult and expensive to do if using direct current d.c For efficient transmission the generated a.c. supply coming from the power stations is … Read more

Cable Size and Protective Device Selection

05: Cable Size and Protective Device Selection The cable most commonly used in domestic electrical installations is the 70 °C thermoplastic PVC insulated and sheathed flat cable which is often referred to as ‘Twin and Earth’ or ‘T&E’ and is available in various sizes ranging from 1.0 mm² up to 16 mm². As well as … Read more

3 Routes to Becoming an Approved Domestic Installer…

To become an approved domestic electrical installer who can self-certify their own work you will need to be a member of a Competent Person’s Scheme. Published in 2020 and in effect from September 2021 the IET Electrotechnical Assessment Specification sets out the minimum requirements to be met by an electrician and or company in order … Read more

Insulation Resistance – Testing

Insulation resistance testing on a new installation(i.e. during initial verification) The object of this test is to verify that the quality of the insulation surrounding the conductors is satisfactory and has not deteriorated or been damaged causing short-circuits and earth faults. It is done at the consumer unit with all the installation switches closed ‘on’. … Read more

Testing Socket Ring Circuits

Continuity of Ring Final Circuit Conductors The objective of this dead test is to ensure that all ring circuit conductors are continuous throughout the ring, with no breaks and no interconnections and also that all connections are electrically and mechanically sound. This test also verifies the polarity of each socket outlet. The test is made … Read more

Dead Testing Electrical Installations

Introduction… Initial Verification: Dead testing must be completed after your inspection and always before any live testing takes place. This is to ensure that all safety systems such as the main earthing, main bonding and all circuit protective conductors are in place and that there is no risk of any short circuits or earth faults … Read more

Electric Vehicle Charging Modes in Amendment 1, 18th Edition BS7671

Introduced in February 2020. Amendment 1 is an amendment to Part 7 of BS7671:2018, Section 722 Electric Vehicle Charging Installations. It does not apply to electric vehicle charging points that employ inductive charging, or to mobility scooters and similar chargers for vehicles of 10 amps or less. “All electric vehicle charging installations that are commenced … Read more