ON-SITE GUIDE - APPENDIX F - PART 2 - VOLTAGE DROP - HOW TO CALCULATE IT - HOW TO SELECT CABLES

This is part 2 of our look at Appendix F of the On-Site Guide or OSG.
This is an often under-used Appendix, but it is so full of very useful information.
We are working to Amendment 2 of the Wiring Regulations, the brown book and all page numbers in this LearnElectrics video refer to the brown Amendment 2 On-Site Guide. The on-site guide follows the Wiring Regulations book BS7671 2018 Amendment 2.
Over time, we’ve had lots of questions about voltage drop …
What is voltage drop for instance …
Where do we start with the formula, and can we have some examples to help us to understand?
How does the formula work? How does it affect the circuit?
And even … Why does it matter about voltage drop? A cable is just a cable … isn’t it?
We will use a basic cooker circuit to show you how we get voltage drop and its effects on the circuit.
There are worked examples for you to follow along with, all fully explained with lots of detail.
We look at the standard formula and at a valuable re-arrangement that you can use in your work.
Some of our very observant viewers have noticed a typo and brought this to my attention, for which I am truly grateful. On a couple of charts I have the Ohm’s law formula for current as I = V ÷ I which cannot be. This should be I = V ÷ R
Ohm’s Law, as a reminder then …
V = I x R
I = V ÷ R
R = V ÷ I
And Power Law
P = V x I
V = P ÷ I
I = P ÷ V
This is video number 215 and to view all our videos type in LearnElectrics all one word into the TH-cam search bar.
Visit our TH-cam channel where we have many more videos on a wide range of electrical topics.

[@johnshiels842]

Another great video David clearly explained, you make them so easy to follow and understand.Always look forward to the next one

[@learnelectrics4402]

Thank you, great comments and thanks for watching.

[@anthonyfindlay466]

Spot on Dave, excellent keep it up I really appreciate you sharing your knowledge.

[@learnelectrics4402]

Thanks, will do, appreciated.

[@AhmedMohammadali-pn3ud]

perfect explanation , thank you

[@learnelectrics4402]

Thanks for watching. Dave.

[@dannysmith2408]

Great video. thank you.

[@learnelectrics4402]

Glad you liked it and thanks for the support, appreciated.

[@brianhewitt8618]

👌excellent, very detailed

[@learnelectrics4402]

Glad you liked it Brian. thanks for watching.

[@halilyasaval4202]

Thank you so much for good explaning

[@learnelectrics4402]

You are welcome, glad it was useful. Dave.

[@rjmateo03]

for which country are these exams sir?
very helpful. great job

[@learnelectrics4402]

UK, Great Britain, but learning about electrics helps with any electrical circuit. Just adapt to your own needs. Hope this helps.

[@no_short_circuit]

Thanks for the video. Very clear as usual (small typo in table though - I= V /I - instead of I=V/R)

[@learnelectrics4402]

Yep, it seems that everyone spotted that. Corrected on that and repeated slides. Glad someone is checking for me, really appreciated, it helps, Dave,

[@ahmedalazazi2895]

An excellent video
It seems that there is a typo mistake
Thanks

[@learnelectrics4402]

Is there. Thanks for watching and for your feedback. Dave.

[@vachikyadegarian1403]

Hi Dave ,Thank you for clear easy instructions.Dave just to let you know I think there is a typing error in your two initial tables. We see I=V÷I instead of I=V÷R..YOUR LECTURES ARE FANTASTIC.

[@learnelectrics4402]

Yes, my typo. Everyone seems to have spotted that except me. Thanks for the feedback, it is appreciated, Dave.

[@franciscogago5961]

Thanks ...

[@learnelectrics4402]

You're welcome, thanks.

[@SSSwilliams]

Shared 👍

[@learnelectrics4402]

Thank you Chris, much appreciated.

[@jchidley]

At 4:08 the total watts is 1,646 and not 2,215 (lower cable resistance, and thus lower overall resistance, should increase the total power).

[@learnelectrics4402]

Thanks for watching, hope you enjoyed it. Dave.

[@jchidley]

@@learnelectrics4402 All your videos are excellent.

[@highgatehandyman6479]

Correction Davo.
At 4.17.
I = V/R. As you know

[@learnelectrics4402]

Wow, that's some super typo. Thanks for that, corrected on that and other slides. Hopefully folk will see through it. That's what I love about you guys, you never let me get away with anything - it keeps me on my toes.
Thanks again, really appreciated, Dave.

[@berkotropia]

If you don't understand voltage drop from this video, don't worry, plumbing is still waiting for you!🤣😂😇

[@learnelectrics4402]

Thanks for watching, appreciated. Dave.