This LearnElectrics video is about cable size and circuit breaker selection using the On Site Guide or OSG as it is often shortened to.
This video and the page numbers that are used are specific to the Brown Amendment 2 on site guide, apart from just one exception from the Brown Wiring Regulations Book because the information is not shown in the OSG.
Be aware that, although Amendment 3 is now released, and we have a video on this (see below), Amendment 3 is a 10 page add on pack that is attached to amendment number 2, so the Amendment 2 books are still valid and new books do not need to be purchased.

Some of the questions that we will answer will include …
How do I use the information in the books to help me?
Or … why should I choose the correct size cable and circuit breaker?
And … what are the formulas that will assist me?

We will start with the Cable Size Formula and show you the correct method to follow and why you should use it. Then we will look at breaker or fuse selection and converting kilowatts and watts into amps and how the OSG will guide you to cable choice. Finally we look at voltage drop in the cables and how to make adjustments in order to comply with the Regulations and then we will make a cable length calculation and give you the formula to do this.

This is video number 251 and to view all our videos type in LearnElectrics all one word into the YouTube search bar.

Take a look at our video - AMENDMENT 3 IS LIVE – WIRING REGULATIONS – BS7671 – NEW AMENDMENT RELEASED – IMMEDIATE ACTION DATE - copy and paste the link below into your browser

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Visit our YouTube channel where we have many more videos on a wide range of electrical topics.

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