2391 Assessment Practice - 1 - Essential Calculations and Circuit Questions
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- เผยแพร่เมื่อ 1 มิ.ย. 2024
- In this video we look at some typical assessment questions such as you might expect for the 2391 assessments amongst others. There are a number of electrical qualifications that all follow a similar prospectus and as you would expect, the assessment process is very similar in each. Understanding one assessment style is of benefit to understanding the others.
This video will take you through 8 typical questions based upon the schedule of test results from an installation inspection, something that you would encounter in a normal working day. Your task is to show that you can understand the data, interpret the data and perform calculations upon it and choose the correct answer from a given selection (multi-choice).
The answers are given to each question as well as a clear and concise breakdown of the method used to arrive at the correct answer.
You may also find the following videos from LearnElectrics to be of help in your assessment preparations
VOLTAGE DROP FORMULAS for Electricians
• VOLTAGE DROP FORMULA ...
Zs - TABULATED or MEASURED
• Zs - TABULATED or MEAS...
WHAT IS R1+R2
• WHAT IS R1+R2. How to ...
This video is No.113 on our TH-cam 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 TH-cam search bar.
Always work safely, electricity can be dangerous. If you are unsure, stop and seek advice.
This video is provided for guidance only. 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.
Hi Dave. I got 96.67% in my 2391-52 multi choice on Monday and you were a huge help. Many many thanks! Practical on Friday... You are a star.
That is fantastic. A great score, you must be really proud. If the videos helped in a small way, then they have done their job. Thanks. Good luck on Friday, Dave.
The interesting part of question 4 was that you didn't need to solve the question to find the answer. The question was about current and only one answer was a current amount. Tricky way to save more time!
That's exactly right. Watch out for these questions, they are there to see if you are paying attention. Dave.
Thank you, Dave. Your videos are much appreciated.
Glad you like them and thank you for watching. Dave.
This is great for the memory!! ... and at the same time learning new formulas never encountered ... Great stuff LE !!! - thanks again.
Glad it is useful and thanks for watching. Dave.
Start my 2391-52 on Monday, really great videos, thank you very much!
Good luck. learn a little every day. It all adds up when you get to your exams and assessments. Lots more videos to watch. Dave.
Thank you, Dave, for your professional explanations and calm and appropriate voice were magnificent!
I hope to rise to the level of knowledge acquired now when taking the 2391-52 exam.
Good luck Dan, keep learning, its a great trade. Dave.
This is a useful tool of examples to know and practice on - Excellent, can we have some more please Dave
Thanks Tony, lots more to come, definitely. Dave.
Thank You, brilliant as ever.👍
thanks Sayeed, thanks for watching. Dave.
Great videos, explained clearly in a way easy to understand, passed my 2391 today and can say these videos got me extra marks
Great job, well done. Keep learning, it's a good trade to be in. It's taken me all around the world. Thanks for the support. Dave.
Excellent and thank you for your time which make me/us more understandable.
Thanks Muhammed, mush appreciated. Lots more to come. Dave.
Brilliant videos.. 👍👍👍
Thanks Keiran. Thanks for the great feedback. Dave.
Great content.really cleared my head as I was confused what to use when n where to use the formulas. Its been a great help particularly for my upcoming exam2391.Great Tips, please do make some more of similar contents .Thank you so much
Lots more to come Bijay. Thanks for watching. Dave.
Great content-thanks
Glad you enjoyed it Danny. Appreciated comments. Dave.
Great video👍🏻
Thanks 👍 Much appreciated. Dave.
Thanks for your tutorials. They are very useful.
Just want to say that QUESTION 8 can also be solved by using the rule of three because it's a ratio:
if 14.06V drop for 60 meters
then 11.5V for X
X = (60 * 11.5 ) / 14.06
Absolutely. Thanks for the contribution to the channel. Dave.
Thank you for this video. Very informative. I’m still slightly confused as to when to use the B1 table from GN3 or page 409 from the regs because they’re the same right, only with a correction factor added?
Different animals Edward.
Table B1 is resistance
Page 409 is current.
Hope this helps to clear the confusion
Good work. It might be worth adding the alternative calculation of VD:
VD= (R1+RN) x Ib x 1.2,1.28,1.04 etc. GN3, pgs 148 - 150. The formula isn't written anywhere but C&G expect students to know and use it.
Thanks for watching. Thanks for the comments. Dave.
This video is a great help as I’m prepping for my exam next month only slight issue I’m finding in all videos on 2391 is they’ve now changed the table numbers and what pages they’re on so I’m struggling to find a lot of these tables
Liam, all the tables are listed in Table of Tables on page 573 of the brown Regs book.
Also, go on to LearnElectrics.com and put Amendment 2 into the search bar. You will get a list of all the Amd 2 videos with the new page numbers and new questions. Dave.
Got my exam in 3 weeks, thank you.
Practice and practice. Watch the videos again. Do a little bit each night rather than cram all the revision into one day. And good luck. Dave.
Hi Dave thanks for another great video.
Do you have any videos on the actual exam (2391). Similar to the ones you done for the 18th edition. Ive got my exam coming up soon and find the best way to learn are through your videos. Struggle to sit and go through 2 hours long videos with my tutor. thanks chris
No, sorry Chris. Planned yes, but not done yet. Good luck.
@@learnelectrics4402 can I ask have you done any actual exam videos since updating chris 5 Months ago? it would be a massive help. thanks
Hi Dave very nice video do more and more please thank you
Thank you, I will. lots more to come and thanks for watching. Dave.
Very interesting, is it possible to have a few more of these videos? I've made the attempt to challenge this but failed. 😔
Lots more to come, definitely. Thanks for watching.
Dave
Thanks a lot
Glad you found it useful. Thanks for watching.
Hi Dave, are these videos still relevant? Taking my 2391 shortly!
This is I wanted . Thank you very much Dave . I hope you will keep this in more further videos .
Yes, lots more on 2391 and 18th Edition over the next few weeks. Dave.
Thanks for all the great videos they have been really helpful. Just one thing i noticed but for question 3 shouldn't the (mV/A/m) actually be 27 as this is for flat cable with protective conductor. Rather than 18 which is used for singles?
page 456 of Wiring Regs. Table 4D5. If its 2.5 twin and earth the mV/A/m is 18. Hope this helps. Thanks for watching, Dave.
@@learnelectrics4402 ah I miss read which one. I read of the amps not the mV
2.5 is 27A reference method C, clipped direct.
Dave have you got a video to help on the practical assessment for 2391?
Its on the list to be done. Thanks for watching. Dave.
Really good video still interesting information even though I got my 2391
Please Can you do a video how to test extraneous conductors with mft like in a garage or outer building so if we need to tt the supply
Its on the list Mustafa. Thanks for the question. Dave.
@@learnelectrics4402 thank you dave
I’m looking to get my 239152 qualification. I have some experience in initial and periodic inspection and testing (4 months ) what would my best route to achieve this qualification be in your professional opinion ?
Robin, a lot depends on what qualifications you already have, what experience you have, are you full time in the trade, part time looking for a change of career. I suggest to everyone that they find 3 training centres in their area and visit each one. Visit, not have a chat on the phone. You need to see and feel what the centre is like. Ask them the questions, what route they suggest etc. and don't part with any money until you've seen the other centres. Courses are not cheap and you want value for your money. Good luck, its a good trade to be in. Be patient and keep learning.
Hi have you done A video similar to this question? The measured value of loop
impedance for a circuit is 0.83 Ohms.
If the temperature at the time of the
test was 20°C and the cable is 70°C
(factor 1.2) what is the corrected
value. Ze = 0.4 Ohms
Thanks
That depends on if you are saying all the loop is affected in which case it will be 1 ohm or if just the building part is at 70C when it will be 0.92. Hope this helps.
Thanks Dave please can you tell me the Sum I can’t figure it out? Is The Sum in guidance 03?
Please have a look if the is right
1) 0.83 - 0.4 = 0.44
2) 0.43 x 1.20 = 0.516
3) 0.56 + 0.4 = 0.916
Thanks Dave Or do you have a better way
Where are you getting Ze = 0.2 on question 6 mate? I'm lost 😅
About 1 minute 20 seconds into the video it says overview of the installation and tells you that Ze for all the questions will be 0.2 ohms. Hope this helps. Thanks for watching, appreciated. Dave.
@@learnelectrics4402 realised this after 😂😂😂
Hi Please can you Guide me where it is in the book for the total insulation resistance formula or the 2 mg I can’t find it in part 6 thanks love you education videos
Thanks Emi, it is on page 109 of the Electricians Guide to the Building Regulations.
Thanks for watching. Dave.
Thanks Dave for your help:)
Hi Dave
Can this formula of VD (Rn x 2 x 13 = 11.55 v in your example !
Rn 7.41 pm x 60 = 444.6 / 1000 = 0.4446 homs
0.4446 X 2 = 0.8892 x 13 Ib = 11.55 v.
I’m I wrong !
Great video’s 👍👍
I think that's just coincidence that it comes to 11.5V as that is fixed value regardless of current and Vd is also affected by length.
❤
Thanks. Dave.
In question 3 there is a MISTAKE.. In both the On site Guide 2018 + A2: 2022 (Table I1) and in Guidance Note 3 2018 +A2:2022 (Table B1) The Resistance per metre (for 2.5mm2 & 1.5mm2 cable) is (very definitely) given as 19.51 milli ohms per metre. Your question states that this is 18 milli-ohms per metre (? ) Where did you get '18' from for 2.5mm + 1.5 mm T&E cable?
Gary, you are looking at the WRONG table. You need to be on page 456 of the Brown Book, where it clearly shows the mV/A/m as 18. It is nothing to do with 2.5/1.5 - this is a no fault circuit so it is line and neutral 2.5/2.5.
Have a look at the video on the link below for a reminder about voltage drop calculations.
th-cam.com/video/TY6L0KB9Lx8/w-d-xo.html
Thanks for clarifying that Dave. Much appreciated to see that you are responding to our questions here on your youtube channel!
Instead of dividing answer by 4. Just divide by 4000 instead of a 1000 for rings. 👍
Lots of different short cuts. Thanks for watching. Dave.
@@learnelectrics4402 thank you mate. You explain very well. Keep it the good work. Sub from me 👍
TAble I1 APPENDIX I
Thanks for watching Antonio, appreciated.
Q6 - Tabulated value is 5.87 ( for B Type - Not 7.28 as mentioned) - sorry if i'm wrong! sitting for test in 2 hrs!!!
You have quoted the MEASURED value which is 5.87.
The TABULATED value comes from the Tables in the Wiring Regs book which is 7.28 as you have quoted.
Make sure you understand the difference between Tabulated and Measured. have a look at this video on the differences and good luck with the exam. Dave.
th-cam.com/video/YVT5d1d3Q8g/w-d-xo.html
@@learnelectrics4402 lovely- thanks for the info.👍