18th EDITION EXAM HELP No.14. ESSENTIAL FORMULAS & CALCULATIONS
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- čas přidán 9. 07. 2024
- Whether you are studying for the exam or just wanting to keep your knowledge current, these videos will be of great help. They focus on the 18th Edition of the Wiring Regulations BS7671 and this video is about the formulas and calculations that you will be expected to understand for the 18th Edition exam.
These are important calculations that are essential to proper understanding and implementation of the 18th Edition Wiring Regulations in your day to day work.
We show you how to use the information available to you and how to quickly and easily find the information and formulas that you are looking for.
We also include several exam style questions in which we guide you through the calculation process in detail, the same process that you will use in the 18th Edition exam.
Each weekly video explores a different part or section of the Regulations and offers advice on understanding.
We guide you through each of the questions so that you can follow the logic behind answering the question quickly and effortlessly and we also provide sample exam questions for you to have a go at yourselves.
This video is made for Amendment 1 of the 18th Edition Wiring Regulations:BS7671
Page numbers and references are specific to the BLUE Wiring Regulations book.
This Amendment 1 video will help with your learning for Amendment 2 exams but be aware that none of the page numbers will match.
Amendment 2 videos can be accessed on CZcams by searching for
LearnElectrics Amendment 2
Whatever your motivation, you will find these videos useful and educational.
This is the fourteenth and last video in our current exam help series. If you are studying for the 18th Edition exam then these help videos will be necessary viewing and if you just want to refresh your knowledge and understanding then they are equally as helpful.
You may also want to view our video on the very important Adiabatic Equations on this link
• ADIABATIC EQUATIONS 18...
And on Voltage Drop on the following link
• VOLTAGE DROP CALCULATI...
This video is No.82 on our CZcams channel where we have videos on a wide range of electrical topics.
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 CZcams search bar.
After watching this series and buying a second hand regs book, I signed up for the 'exam only' 18th edition test. Instead of paying £380 it cost me £150 plus £20 for the book. You saved me over £200, so thanks a lot for putting this course out there, its most appreciated.
Congratulations on your success. The hard work was down to you. Keep learning, it's a good trade to be in. Dave.
Hi, where can i sign up for 'exam only' please help!
@@elguada123 it depends where you are. I’m in Liverpool so I contacted a few local centres. The one I used was tradetraininguk.
There’s a few online places you can do it if you Google ‘18th edition exam only’ a few different companies will come up.
Dave sat my 18th edition exam on Thursdays and passed with flying colours. Would of never been able to of passed if it weren’t for your videos. Really appreciate them, like I said before your students and CZcams are lucky to have you. Keep the videos coming. Thanks a lot. Chris p
That's great news Chris, well done. Thanks for the compliment but you passed because you bothered to learn the subject - well done. lots more to come, spread the word. Dave.
I passed my 18th edition. Thanks for these your videos.
Great job and very well done. Really pleased. Your effort came good. Keep learning, its a great trade.
your video helped me and i pass my exam. long live and God bless you
Well done, it was worth the effort. Keep learning, its a good trade to be in. Dave.
Yet another indispensable source of reference. Keep em coming 👍🏼👍🏼
Thank you. Great feed back.
Just wanted to say a big thank you for the 18th edition videos, they helped me pass the 18th exam with a very respectable mark.
Fantastic Aaron. Well done mate. Don't stop learning now. Too many sparkies hang up their brain cells after they pass the exam and they slowly lose the knowledge.
Glad we could help, pass on the channel info and help others. Dave.
thank you for such a beneficial video.tq
Thanks for the video. As an adult learner I'm a bit confused with your example of Ca. I understand how you calculated 22.52 amps of current at 30 degrees but you then say that at 50 degrees it will carry 13 amps without overheating - should that not be 16 amps?
Well spotted and thank you. Yes, my typo. Should be 16 amps, the breaker size.
It's a good job someone is paying attention. Dave.
got me there too
I have watched all the 18th Edition series. They all are great and helpfull videos. I can't thank you enough.
Never stop learning Abreham and good luck with the exam. It's not about what you can remember, it is all about finding the answers in the book. Lots more videos to come. Dave.
I had some of these questions in my mind for years. Problem solved. Thank you Dave.
Happy to help Sajad. Thanks for supporting the channel. Dave.
Just passed my 18th Edition exam. So much help from Dave's videos. Excellent teaching once again! Watch his videos, do his questions and you'll pass. He should really be charging for this LOL 😆
Fantastic news that you passed. Really happy for you.
And thanks for the great comments, but really, it is your own commitment that helped you to pass. Spread the word about the LearnElectrics channel, that's the best way you can repay the help. Dave.
@@learnelectrics4402 will do Dave!
I have my 18th exam in a few days. No calculation questions whatsoever have come up in the practice questions provided by my online course, which I have run through about 50 times. I would question the need to learn the Actual Voltage Drop calcs, as that formula doesn't appear in the regs book. The 18th exam is supposed to test your ability to find answers in the regs book. It's not a memory test. We haven't been told to bring the Onsite Guide, so I'm very doubtful that a volt drop question would come up.
Just thought I'd mention that to help others. All that being said, thanks for the video, I feel more confident now if a calcs question does come up.
It is in the Regs book. Take a look at page 377 - Section 5. It's there in words which is why most people miss it.
@@learnelectrics4402 thanks for the quick reply! I came back to delete that comment because I realise I was wrong. I bow to your superior knowledge!
I'm a bit disappointed in my course provider for not supplying practice questions which involve calcs. I've been getting 58 or 59 out of 60 in practice, in less than 1 hour, so I should be ok, but I just don't want to get unlucky with the questions and embarrass myself!
Great Video, good reminder of common formula's that all electricians should practice and be conversant with.
Absolutely right Angelo. Thanks for the support. Dave.
Many thanks for your generous help.
Thanks Mark, you are very welcome, glad the videos help. Dave.
I bought the 18th edition book jut to go through this 14 series tutorial and become quite good at this! Thanks!
Great news. So glad you are learning and thanks for watching. Lots more to come. Dave.
Thank you, now I am starting to learn how to read this encyclopedia correctly by following your valuable videos, but I need to follow up more, as you are a sophisticated person in education, and I commend your efforts that you give us to learn
Thanks Radhi, great feedback.
Keep learning a little every day, it will make sense and thanks for watching.
Lots more to come.
Dave.
@@learnelectrics4402 when I read b.s book found table 4d1b page 402 it use R&x&z to calculate voltage drop it start from 25mm cable size who can use it.with my regards so I appreciate your hard work ( thanks)
Hi Dave, thanks for the afford you have put for these videos. i appreciate it. thanks for the very helpful videos . Moji
Thank you Moji, glad you find them useful. Lots more to come. Dave.
Very useful to know, video.
Glad you found it useful. Appreciated comment.
Thanks for the very helpful vedios
Thanks Mokhtar, glad they are helpful. Dave.
Hi, your Q7 from lesson 13 asked for 32amp which, according to the table on p364 for 0.2 seconds would be 280A, the 450A is for 45A. I thought i was going mad when I couldn't see 280A as an answer option when I did it ;-) thanks for the videos though, they're great help
Yes, my typo Craig. A few of you have spotted that, so much for copy and paste.
But it does show that you are paying attention. You are now an expert on this section and good luck with your exam. Dave.
@@learnelectrics4402 exam yesterday, 92% so thanks again, really enjoyed the videos 👍🏻
At 10:25 , you are saying that: "the cable that carries 22.5 amps at 30 degrees will be able to carry 13 amps at 50 degrees"??? Could you please explain where did you get that 13 amps from? It dosnt seem right.
I mean, you worked out that at air temperature of 50 degrees our cable was able to carry 22.5 amps; and based on table 4D5 we must select a cable that carries a current equal to or bigger than that, which is 27 amps at 30 degrees.
50 degrees.
50° ----> 22.5 amps
30° ----> 27 amps
The actual exact answer is 22,5 amps, but you cannot buy 22.5A cable for Ref method C off the shelf. so we would install 27A or 2.5mm cable. Hope this helps. Dave.
At 18:30 is the length of the circuit L the length of the cable or is it double this to allow for neutral path
From the CU to the point of use. Hope this helps. Dave.
dear sir yes you are absolutely wright thank you for your correction
Thanks Azizur. Believe me, you won't forget that now, and that is good. Dave.
@@learnelectrics4402
Hi Dave It Azizur Rahman
How to do r1r2 ring 2.5 line conductor 1.5 cpc and some 4mm line conductor 1.5 cpc
Please tell me. Thank you
At 3:11 what determines the size of fault current in practice in the field ?
Fault current is derived by ohms law from Ze or Zs, whichever is being tested. Thanks for watching, Dave.
i just passed for my first time today because of you thanks very much
anyway i can send u a tenner through paypal
Great job, well done. You took the time to learn and it paid off. Don't stop learning now, keep going, it's a great trade to be in. Dave.
The best thing you can do for me is to spread the word about LearnElectrics. Dave.
@@learnelectrics4402 will do
Outstanding video Dave, just one query. If I have a T&E with reference method B or E used, these are not on table 4D5 (p409), am I right in thinking we would revert to table 4D2A (p403) for this situation?
For Twin and Earth go to page 390. The bottom half of this page (Table 4A2) is what you want for the installation methods and then page 409 Table 4D5 for cable sizes.
@@learnelectrics4402 yes I understand the 100, 101.. etc methods. But how about t&e in surface trunking or conduit, ref method b? What current carrying capacity table would be used? Specifically for methods b or e?
The regs suggest that T&E should not be in trunking or conduit, it should be singles or multicore as per the drawings in the table. If you must put T&E in conduit you will have to try and find a comparison for multicore for your own circumstances.
Hi Dave, I got 280A for 0.2 seconds on question 7(BS 88-3 FUSE) of the previous video. Different to your answer here.
Yes, you are right. The question should have stated a 45A fuse. Well spotted, I've corrected it now. Just goes to show that you are learning something, good luck with the exam. Dave.
@@learnelectrics4402 thank you for the great videos. Really good TEACHING!
Hi there I just wanted to know is this your last video for 18th edition series? or is there more to come?
No. 14 is the last for now. Another mini-series will appear soon with lots more questions etc. Thanks or watching and good luck. Dave.
appreciate ur videos too much , in question 7 the answer should be b 280A (0.2s,32A)
Yes, my typo. Thanks for watching.
Is there any chance you could put all your 18th edition exam learning videos into a playlist on your page as they are quite hard to find the next part each time. Thank you
Excellent idea Tom, I'll look at that. Also, if you go to our dot com website you can search for 18th Edition session1 - 18th Edition session 2 etc. up to session 14
Thanks for the useful tip. Dave.
great video many thanks can you do more live testing and inspection , also PAT testing thanks again
Certainly can, those very subjects are being planned. Thanks for the feedback. Dave.
Thanks, may I know why the answer of Q7 (Appendices) is A (450A), not 280A?
Yes you may. Q7 should ask about a 45A fuse nit 32A. Put 45 in and you'll get the right answer. My typo. oops, sorry.
Thanks for the video alot. But question 7 from previous video, should the answer not be B, as the for 32a bs 88-3 on page 364, it says 280a, you have chosen answer A which is 450a way above 280a. Can you explain please. Thanks
A typo. It should be a 45A fuse. Try that. Thanks for watching.
thanks mate. can you tell me how calculat K?thanks
We don't calculate k, the boffins tell us what it is in a set of tables for different materials, thanks for watching. Dave.
Do u have a course and exam centre?
No, not any more. Thanks for watching, really appreciated. Dave,
dear sir I like the your video I am very very happy and watch your every video it is Wonderfull and understanding I=1150 t=0.5 seconds K= 115 it gave me answers 7.071 mm2 but your answer is 25mm2 please can you explain me may be I am wrong calculation. thank you
Azizur, you have made the same mistake that many others also make. Read the question properly, do the calculation in stages. t is 5 seconds not 0.5.
Try again, you won't forget this now. You've just added to your learning. We all learn by making mistakes. Good luck. Dave.
@@learnelectrics4402
Hi Dave It Azizur Rahman
If unknown r1r2 for ring how to do voltage drop by ohms
Thank you