18th Edition Exam Questions Help - 4 - Calculations
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- Опубліковано 6 сер 2024
- Continuing our series of help and tips videos on how to answer the questions in the 18th Edition Wiring Regulations Exam, this video is Session number 4.
There will always be questions that require you to calculate an answer. Indeed, it is an essential part of our trade, of being an electrician, that we can make calculations of circuit parameters correctly and not have to rely on guesswork or which way the wind is blowing.
In this video, we will concentrate on the two main calculations from the Wiring Regulations book. These are the Adiabatic Equation and the Voltage Drop formulas.
The adiabatic equation will allow us to correctly select a suitable size protective conductor, or earth, that will handle any fault currents safely. Why should we worry about the correct size? Copper conductor is expensive, if we install too big a size then yes, it may do the job adequately, but you or your customer have just paid extra money for copper that is not needed. And of course, too small a size can have disastrous consequences.
By rearranging the Adiabatic Equation, we can also determine how long it takes for a cable to reach the critical limiting temperature. Will the fuse or breaker trip before the cable is damaged by thermal effects.
The Voltage Drop formula will tell us the voltage drop in a certain length of cable and we can also work this backwards and determine the maximum length of cable to not exceed the voltage drop limits.
The video series is intended as an enhancement to classroom learning where you should be taught to understand the Regulations and their importance to the safe and correct functioning of electrical installations. Viewed alongside formal training classes these videos will certainly enhance your skills and improve your chances of success in the exam.
You can also view our video - ADIABATIC EQUATIONS, by clicking on the link below
• ADIABATIC EQUATIONS 18...
And to view our video - VOLTAGE DROP CALCULATIONS, click on the link below
• VOLTAGE DROP CALCULATI...
This video is No.115 on our UA-cam channel where we have videos on a wide range of electrical topics.
We also have a 14 video series of 18th Edition training videos (Playlist A) which can be accessed through the following link …
• 18th EDITION EXAM TIPS...
To see a full list of all our LearnElectrics videos, click on the link below.
/ @learnelectrics4402
You can also view all our videos by typing LearnElectrics all one word into the UA-cam search bar.
Always work safely, electricity can be dangerous. If you are unsure, stop and seek advice.
Every electrical situation is different, please check and ensure that you are applying this learning information to your own individual circumstances correctly and safely. If in doubt, stop and seek competent advice.
Ah Dave, this takes me all the way back to Lisburn Technical College, Northern Ireland, circa 1974/1975when I started to serve my time, at the princely sum of £9 per week, and the advent of the new Sinclair calculator, which cost £15, and had to be ordered--one of life’s life changers, along with the cordless drill etc--whilst as you know I’m retired now, I look forward to your videos--exceptional knowledge, and graphics.
Many Thanks as always for your efforts-D
Thank you Dave, my journey into electronics and electrics began in 1978. A great trade, lots of travel, lots of good stories. £9 a week, I bet you felt like a Lord on pay days. Thanks for the comments. Keep watching. Dave.
This is fantastic. I can't stop watching your videos since I discovered it on UA-cam. Something I left the college without been able to work it out I just learned in less than 10 minutes. You are Wonderful. Thank you so much.
Happy to help and thanks for the great comments. Keep watching, lots more to come. Dave.
Im a huge fan of these 18th edition (help & tips) and exam questions, keep them coming👍🏻.
Absolutely Dibbo. Lots more to come. Dave.
Absolutely wonderful! Thanks Dave for keeping us on our toes, makes me feel like I'm back at college again. Love your passion for the subject and your desire to impress these key points firmly in our minds. Keep them coming, as it's good to test ourselves so that we don't forget. Will be putting it into practice more.
Many thanks.
Thanks Francoise. Yes, keep you on your toes, me too. Always try a learn a little more each day. Lots more to follow. Dave.
Hi Dave, from an old spark from the 60's. I very much appreciate the effort put in to create such excellent tutorials, how easy it is compared to my days in the early 60's everything was done longhand no calculators, they say use it or lose it, I don't think I could calculate square roots longhand now? I will have to give it try and see if I can remember. Keep these excellent videos coming you are a great asset to the young apprentices.
Peter.
Thanks Peter, great feedback and appreciated. Longhand? It's so easy now. I can remember using slide rules. I've still got mine, somewhere, but I bet I can't remember how to use it without some effort. Thanks for watching. Dave.
Your videos helped me more then I learned in course
Glad they were useful. Thanks for watching.
Thanks Dave.
Great video.
i appreciate you time
Super feedback Abdirizak, thanks for watching.
Thanks for these ever so well explained and set out tutorials.👍
My pleasure Zed. Glad you like them and thanks for watching. Dave.
Really like the thank u sir
You are welcome. Thanks.
Very impressed🤗
Thank you Stephen, much appreciated comments.
Fantastic content.
Glad you found it useful Billy, appreciated. Dave.
HI! QUESTION 6: answer is D - 2.06 seconds not c - 2.06 seconds thank you
Thanks Edouard, you are correct. A small typo but hopefully you found the right answer. Thanks for watching. Dave.
Hi Dave it is very best video ever in UA-cam, can you do zs length and volts drop together video thank you very much
Absolutely we can, keep watching. Thanks for your support, appreciated. Dave.
I’m living in UAE , and I cant tell how thankful im to you ! Your are the best . Are you providing paid courses for a broad engineers like me to teach as much more about bs7671?
Thanks Aideed, great feedback. No, I don't do face to face teaching anymore. Lots more videos to come on 18th and 2391 etc. Keep watching and learn a little more each day. Dave.
Hi Dave can you do max zs length and volts drop together. thank you
Thanks Azizur, your request is now on the list to be done. Dave
Hello Dave, I hope you are doing well. In the voltage drop equation we use Ib. But, in design method we select Iz based on In. these patterns are not similar. If we can use Ib in voltage drop calculation, then why can't we select Iz based on Ib? Do you have any idea?
Using In for voltage drop looks more smart and conservative, It will make the circuit, future change proof 😃 . In my country taking branches or spurs from available circuits is popular. Maybe in UK you have more strict rules, but I think at the end of the day people are people and show similar patterns. Or even without taking spurs, there is the chance of replacing the electrical equipment and therefore change of wattage and current. I vote for using In in formula 😉
Sajad, there may be other ways of calculating answers but I must show the methods that are expected in the exams. Thanks for the comments and thanks for watching.
See above Sajad. Thanks for your support and enlightening comments. Dave.
@@learnelectrics4402 True, your focus is on exam, but your nice channel absorbs broader viewers than just exam participants.😊 I learnt a lot watching your high quality tutorials. Best wishes.