Testing Zs - Why it is so important?
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- Опубліковано 6 сер 2024
- An overview of testing the Earth Fault loop Impedance (Zs) of an electrical installation.
This test verifies the protective device will operate in the required time, and that you do actual have a connection to the earthing system - Фільми й анімація
without a doubt the best instructional video on Zs testing i've seen, & the rest of the videos JPElectrical are equally as brilliant....thank you for posting these videos!
Thank you Alan that really kind of you to say
This is the best explanation on Zs ever. Be blessed
Thank you for your kind comment
Love the clarity of the animation, makes the understanding so much clearer to comprehend, subscribed.👍
Thank you Zed Zed. Really Appreciate the comment and that you have subscribed.
Very good explanation and easy to understand it gives the technical side and visual side .......I find it much better than watching a video.
Thanks Lloyd, appreciate you watching and commenting
It is a great video and very helpful
Can you please tell me how to check the discrimination in your whole system
How to know the response time for each protective device
How to control the response times as you mentioned that the distribution time is 5 seconds whereas the nearest device is 0.4 seconds
Many thanks to you
Thanks very much for a comprehensive explanation. New subscriber now.
Really enjoyed the video. Interesting, informative and explained in a clear and concise way. I also think there is considerable added value in you comments about the practicalities of real world scenarios. Also reworking calculations to show the impact changes/installation methods have on circuits is great. You often need to understand the background to fully understand a subject. So often people/UA-camrs just provide the exact detail and whilst it can be very useful and I’m grateful for their efforts. They could learn a lot about how to really provide an in-depth knowledge and understanding of a subject. Keep up the good work. Your video reminds me of just how much I’ve forgotten haha! In my career, I’ve always aspired to improve my position, which I’m pleased to say I’ve achieved. However, it also demonstrates just how removed I am, from the day to day world of Electrical Engineering.
The joys of multidisciplinary projects. It’s all Health & Safety, Finance, HR Issues, Project Management and the list goes on.
Again, keep up the good work…
Thanks Dave . Alway good to get feedback from people in the industry. Thanks for watching and taking the time to leave a great comment.
This is brilliantly explained & great video!
Top marks!
Excellent!!
MG.
Thanks very much, I really appreciate it.
The best explanation of Zs i saw. Thanks. 👍👍👍
Thanks davidofff25. I really appreciate you watching and commenting
Brilliant and very well explained,. Excellent!
Thanks very much for the comment, Appreciate it.
Welcome back.Great video and graphics as always(especially for Learners).I have always struggled getting my head around why distribution circuits and final circuits above 32A are allowed 5 sec disconnection time,so the part on "discrimination" makes it easier to understand.Still seems a long time under shock conditions?.Look forward to the next instalment.Thank you.
Thanks for the comment , really appreciate it. Re discrimination, and the five second disconnection time.
There is a lot of debate around its origin. I don't have a definitive answer for its use.
Distribution circuits tend to be quite simple, and generally solid in construction. i.e SWA from one distribution board to another, with no user interaction on that circuit, by that I mean no socket circuits and such. So the chances of someone in contact with that circuit is not very high. Local circuits off the distribution circuits will have 0.4 disconnection times.
Some Say they just increased the disconnection times to make it fit around 3036 fuses
Some articles talk about touch voltages, and protective and supplementary bonding considerations.
This is generally in commercial/industrial systems, so skilled persons are likely to be involved.
I clearly understand how you explain well put together
Thanks for watching and taking the time to comment.
Excellent video👏👏👏👏thank you 😊
very good explanations on all your videos.
Really help me to understand the theory better.
Would it be possible to explain Zs at furthest point when measuring by detailing whether MCB is on or not etc...
Brilliant explanation thank you
Hi munafmufc01 Thank you for the nice comment
Great video
Very good indeed, many thanks.
Better explaination ever in my 2 years Electrical course ive never learned as i learn from your channel thanks for helping us
Thank you emil gemc. really appreciate it.
Thanks for your great presentation. One point: At 14:40, on the right side stated correction factors from 10C, but shown from 0C. Is it a typo? Or I am missing something!
thank you very much!
Excellent 👍
Thank you Paul
Correction you say you can't remove the RCD to get a test, yes you can if you're meter is likely to trip the RCD then you remove the RCD from circuit and temporarily replace it with a suitable mcb do the test then replace the RCD . Great video well presented and informative.
Thank you Sean. Removing the RCD would not be a practical solution, and not something I would advise. The RCD is a two pole device, and the MCB is a single pole device. So what would happen with the neutral? If the RCD causes issue, use the dead test results . R1+ R2 and Ze to get your Zs..
@@JPElectric yes but some tester manufacturers say in there meter instruction manual if the tester does not have D lock or no trip function then the RCD WILL HAVE TO BE REMOVED FROM CIRCUIT AND TEMPORARILY REPLACE WITH A SUITABLE MCB AND YOU MUST REPLACE THE RCD AMEDIETLY AFTER THE TESRT. Ie kewtech kt62 multifunction tester and the Robin kts 1620 some other models as well. Agreed it would be a pain in the ass but some time we just have to put up with it not ideal I know. Great video all the same I will be watching more so keep them coming and keep up the good work.
I think thats advice from some time ago. Those models did not have the low current test feature, we have today.
All modern meters have a low current setting. And in an EICR, Dismantling is discourage as it can introduce faults.
@@JPElectric I don't know were you get that from, I have never read that in the regs, considering the fact that the regs and and none of the part p scams like Napit JIB niceic and all those have no impact on test instruments when they say your test instruments 16th 17th or 18th edition ready that Is rubbish it is a selling tactic to get you to spend money, BS7671 state if ANY meter can perform the tests then it will be complyant with BS 7671 provided it is in good working condition has no external damage and is properly maintained and calibrated and that the test leads conform to GS38 not at any point dose the regs mention test instruments by brand manufacturer or model
I agree, older test meters are still fine for continued use.
Thanks again ❤
Thank you Saman
hello,
would appliances like kettles, fridges, wifi boxes, or microwaves etc need to be unplugged whilst doing the zs and r1+r2 test? i’m not sure if they would give false results
Love your videos, what program do you use to make the slides? I've taken a new job and this would brilliant if I could attempt something like this
Hi bluetilly, thanks for watching, I use adobe illustrator
Thanks JPE
Thanks for the comment Chris.
Thankyou!
For a live Zs test on things like cookers and light fittings, don’t you need to disconnect the cooker cable from the cooker so the cooke4 heating elements etc are not in circuit and for the light fittings test, do you not remove the lamps? Thanks
Not on the Zs test. You are thinking of the Insulation resistance test.
Hi, Cmin is used for calculating the max Zs of a breaker. Uo x min divided by la . But where is Cmax used please?
Thanks
Hi Adam Cmax is the maximum voltage correction factor to take account of voltage fluctuations. It is 1.1 Section 722 of BS 7671 gives an example of use
Thank you 🙏
Thank you for watching Khan
@@JPElectric
Can you please do video on maximum demand please..🙏
@@JPElectric Can you please do video on maximum demand please
Calculation.
What about if we can called internal Ze
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Great video but could you incorporate into the graphics how zdb and zsdb are found as I am struggling to get this in my head . As main consumer unit in the house with another board fed off one of the spare ways to garage then feeding other circuits where are zdb measured and or zsdb ??
Hi Paul, the term Zsdb, is not really used (AFAIK).
If you test another board fed from the main consumer unit, you do a Zdb reading.
Just think of it as a Zs test at the second board.
You do not disconnect any earthing on a Zdb.
Zdb is the impedance at any other distribution board. You only have one Ze, but you can have multiple Zdb readings. If you have a look at the Testing Ze video this is explained there.. Thanks for watching.
@@JPElectric And then obviously you add the R1+R2 of any circuits to the ZDB from the say garage circuits which would give you the Zs of that circuit as this would be at the most distant point of the installation .
Yes, thats right, if you wanted to calculate it. Using the Zdb + R1+R2. Or you could do a measured Zs reading at the furthest point. Volt drop is something you will want to consider though, and this is from the origin.
👍👍
My tests also confirms Polarity
Imagine that, the nanny state 'government' officials wanting skilled, experienced 'Electricians' NOT to work on live conductors for testing and relying on calculated readings...Oh, hold on....
This is an insult to the intelligence of these skilled people..
Thanks for the comment EF. I do agree. A well trained and experienced electrician is perfectly capable of working safely around live conductors.