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.


AFDDs - Arc Fault Detection Devices, with emphasis on their availability and use in the UK
Basic Principles - Basic principles of electricity and electrical installations
Circuit Breakers - What's inside circuit breakers or MCBs, explanations of various types and different applications
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
Fuses - Fuses of various types explained and demonstrated
RCDs & RCBOs - Redicual Current Devices including RCDs and RCBOs

Most recent update - 17th February 2019

NEW AFDDs Arc Fault Detection Devices - Arc fault detection devices from a UK perspective, also known as AFCIs - Arc Fault Circuit Interrupters - in other countries.
NEW Circuit Breakers MCBs - Circuit breakers, also known as MCBs or miniature circuit breakers.
NEW Residual Current Devices, RCDs - Residual current devices, or RCDs and the combined MCB and RCD known as an RCBO.
NEW Fuses - Explanations of various types of fuses and demonstrations of how they work.
NEW Initial Look at AFDDs Part 1 - A look at an Eaton 3 module AFDD and various basic tests done on it.
NEW Initial Look at AFDDs Part 2 - In this second part, further tests are done with the Eaton AFDD including overvoltage.
NEW Initial Look at AFDDs Part 3 - The thid part considers various BS7671 regulations and other materials from several manufacturers of AFDDs.
NEW AFDD Documents and Marketing Materials - A selection of documents from various manufacturers of AFDDs and others.

Previous update - 4th August 2018

Types of Circuit Breakers, B C D K and Z - Circuit breakers or MCBs and why there are different types are such as Type B and Type C. Covers the three most common types plus two others.

Older update - 29th July 2018

Neutrals in AC electrical circuits - What a neutral wire is, how neutral is derived at the supply transformer and why a neutral wire isn't always safe.

This section contains 24 pages of information.