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
READ MOREPermitted cable routes / zones BS7671:2018 I’ve recently been asked a question by one of our 18th Edition students and think it would be useful to see it here. ” My inquiry is quite simple really, but I am a little confused as to what is acceptable practice
READ MOREThe often misunderstood regulation concerning fires and cable supports… Recently I was speaking to a builder who had been refurbishing an old terraced house and he was telling me about the electrician who completed the rewire. The ceilings on the ground floor had been removed but were going
READ MOREIsolation and Switching in Domestic Kitchens… Let’s take a look at a few definitions first… Isolation: Function intended to make dead for reasons of safety all or a discrete section of the electrical installation by separating the electrical installation, or a section thereof, from every source of electrical
READ MOREThe most common cable found within a domestic electrical installation is the PVC insulated and sheathed Twin and CPC cable – also known as Twin and Earth. A PVC three core and CPC is also used on two-way lighting circuits, smoke detector interlinks, fans with timers and also
READ MOREKey Points of… Isolation: 537.2 Every circuit / installation must be provided with a method of isolation from the supply. This isolation device should also be provided with a method to prevent unintentional or inadvertent reinstating (usually lockable). In a TN-S or TN-C-S system it is not necessary
READ MOREThis 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
READ MOREA.C. current flowing in a conductor creates an alternating magnetic field. This is made stronger if the conductor is surrounded by a ferrous ‘containing iron’ enclosure such as with steel wire armour ‘SWA’ or steel conduit and also if a single conductor enters a ferrous enclosure on its
READ MOREOver 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
READ MOREProtective Conductor Sizes… Regulation 543.1.1: This can be achieved by either calculation (543.1.3) or selected (543.1.4) from Table 54.7. The formula used in 543.1.4 for calculating the size of a protective conductor is covered in great detail in a session inside our 17th Edition online course. Selecting from
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