Electrical Theory and Regulations

This section contains information of electrical basic principles, wiring regulations, circuit design and more. As with the main Electrical section, this is applicable to the UK and UK wiring regulations. Other countries will be similar in many respects, but there will be important differences in some areas.


Basic Principles - Basic principles of electricity and electrical installations
Earthing & Bonding - Earthing, main protective bonding and supplementary bonding explained
Electric Lighting - Electric lighting in various forms, how they work and where they are used
Protective Devices - Fuses, circuit breakers, residual current devices and more
Wiring Regulations - BS7671 Wiring Regulations as applicable to electrical installations in the UK

Most recent update - 17th February 2018

NEW Voltage, Current, Resistance & Power - Explanation of basic electrical terms voltage, current, resistance and power.

Previous update - 11th February 2018

Lighting - Electrical lighting in various forms, how it works and how it can be used.
Fluorescent Lighting - Fluorescent tube lighting with a magnetic ballast and glow starter.

Older update - 3rd April 2016

Basic Principles - Basics of electrical theory centred on mains electrical installations.
Protective Devices - Fuses, circuit breakers and RCDs examined, taken apart and tested.
Earthing and Bonding - Earthing, main protective equipotential bonding and supplementary protective equipotential bonding are explained and illustrated.
Wiring Regulations BS7671 - A selection of topics on UK regulations for electrical installations, BS7671.
Diversity and Maximum Demand - An explanation of diversity and how the maximum load of a circuit or complete electrical installation can be assessed.
Voltage Drop in Electrical Circuits - Voltage drop explained - why it occurs and how to minimise it.
Earthing for Electrical Installations - Earthing for mains electrical installations in the UK.
Main Protective Equipotential Bonding - What Main Protective Equipotential Bonding is, and why it is installed.
Supplementary Protective Equipotential Bonding - The purpose of supplementary protective equipotential bonding and where is typically installed.
Circuit Breakers - What's inside, how do they work - How a typical circuit breaker works for overloads and short circuits, plus a look inside.
Residual Current Devices - How residual current devices (RCD) work and what is inside a typical example.
Fuses Explained and Examined - What fuses are for and how they react to short circuits and overloads.
Rewirable and Cartridge Fuses Tested - A selection of rewirable and cartridge fuses are subjected to overload and short circuit conditions.
Bathroom Zones as defined in BS7671 - Definitions of the various zones for bathrooms as found in BS7671.
BS7671 Wiring Regulations and On Site Guide (Yellow 2015 Edition) - A look at both BS7671 and the companion On Site Guide, 17th edition 3rd amendment as published in 2015.
TT supply with a metal consumer unit - Problems in complying with the 17th edition 3rd amendment wiring regulations with TT electricity supplies..

This section contains 19 pages of information.