WHAT IS R1+R2. How to change the values, what do they mean.
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- Опубліковано 9 січ 2021
- Have you ever wondered why electricians have this fascination for R1 and R2?
What is it? What does it mean?
Or perhaps you do know but you just need to understand it a little more and to be able to safely make changes to the resistance values of R1 and R2.
If you can get R1 and R2 right then everything else should fall into place.
The video asks - what can you do if you arrive at a property to carry out work and the Zs figures are already at a maximum and you need to extend the circuit?
It happens a lot, especially if the house was wired to 16th Edition or earlier.
The video shows how this can be achieved safely and in accordance with the Wiring Regulations.
Lots of answers and lots of solutions will be found in this Tech Tips video.
To view all our videos, click on the following link
/ @learnelectrics4402
SEE ALL - To view a list of all our LearnElectrics videos, click on the link below.
There are many videos on many electrical topics including Installation, Part P, 18th Edition, Testing, Certification, Lighting, Sockets, Ring Circuits and much more.
ua-cam.com/channels/YaJQnpO4XAp0yCgqzMkmfA.html
So how will you do this test on a heating switch that has a paralel earth path, It has two earth. Please explaine if possible.
Thanks for making these videos, the amount of information that needs to be learned is daunting, but the way you explain things and break the subjects down makes it a lot easier to understand.
Thanks Nick for the really nice comments. There is a lot to learn but try to learn a little bit every two or three days. A dripping tap will fill a bucket. Also, draw some of the diagrams and pictures you come across, drawing it makes you concentrate on what is really on the page in front of you. The more you learn the better you become and your earning potential goes up. Stick with it, it's a good trade. Dave
There’s no other UA-cam channel that breaks things down as well as you! Really appreciate these videos. Clear and concise making everything so clear to understand 👍 can’t wait to see this channel grow 👏
Fantastic feedback. Thank you so much. It has really made our day.
Lots more to come.
Bux
Without doubt the best learning videos about electrics on you tube. Thank you very much.
Thank you so much. Really appreciate the positive feedback. Dave.
Brilliant video/videos..being explained so clearly is so helpful
Thank you Dan. Glad we can help. Lots more to come.
Dave
Thank you again for the best explaining R1+R2
Our pleasure. So glad that you found it useful.
You make it so easy. I learn so much from your videos, thanks.
Glad to hear that and thank you for the comments. Dave.
Spot on , thank you so very much for this informative video. I like and love your videos, you make learning electricity so simple and understandable..
You are very welcome, thanks for watching and thanks for the support. Dave.
Great channel! very helpful content.
Thank you!
Thank you for the positive comments. We do appreciate the feedback. Bux
Honestly mate, you are a Godsend. Your videos are absolutely flawless. Thank you 👍
Thank you Asim, your comments are really appreciated. A Man U supporter? I was born within sight of Old Trafford. Keep watching, lots more to come. Spread the word. Dave.
@@learnelectrics4402 Thanks for your reply Dave. Old Trafford is God's country. I'm originally a Salford lad but now live in Prestwich. Thanks for the brilliant videos and yes, I'll spread the word. Take care pal.
Stay lucky Asim and thanks.
I think you’ve a bit of a talent in explaining things..very well explained. Love the channel.
Thank you Paul. A great compliment and truly appreciated. I just try and put the message across as I would like it explained to me. Glad it works. Dave.
Fantastic insight as usual. Thank you Dave and team 💪🏾
Glad you enjoyed it, thanks for the feedback. Dave.
Best vids on the Internet are here! Thank you so much, please keep up the good work.
Last note: where can one find a greater range of breaker Zs permitted ranges. I'd like to keep them handy and printed out.
Thanks for the great feedback Galliger.
You will find the measured Zs maximums in the On Site Guide Table B6 which is on page 131 in the blue OSG.
Take a look at our video "35 is the Magic Number" on the link below and you may not need to print anything out.
ua-cam.com/video/URBD4llLU6Y/v-deo.html
Glad you are enjoying the videos, lots more to come. Spread the word, it all helps. Dave.
You are a legend thank you
I was searching for years to get a clear picture , now you made it
Take a look at this video as well. Thanks for watching. Dave.
ua-cam.com/video/6Re2sqGVoWY/v-deo.html
Am learning alot from your videos. Keep it up
Thank you very much for your positive comment. We do appreciate the comments. Dave.
Really do not know how many ways I can say thank you for these videos, you're a legend.
Just spread the word, that's all the thanks I need, and keep watching. Lots more to come.
@@learnelectrics4402 Have been spreading the word and will continue to do so for years to come. Just know your work here is very valuable in many respects. And yes I'm looking forward to travelling the world a bit! Stu
thanks for making these videos, you make it very easy to understand I like your videos very much.
Thanks Nicholas, that's exactly what we like to hear. Lots more to come, keep watching. Dave.
Thank you for your videos very helpful and clear. Please keep going, refresh our memory because of constant working no time for reading unfortunately .
I know what you mean. Trying to keep the videos to 15 mins or so and one topic for one video. Thanks for the support. Dave.
Perfect video thankyou
Explained earth and neutral clearly and good visual
Thank you, and thanks for watching. Dave.
Thank you Dave for another great video.
Thank you.
Very good explanations for us
Thanks Joseph, appreciated. Dave.
Well done mate ,you are professional
Thanks for the great feedback, it does mean a lot to us, it makes all the hard work worth it.
Brilliant video thanks.👍
Glad you enjoyed it and thanks for the feedback, appreciated.
Nice one dave another great video for learning 👍👍 brilliant
Thanks for the positive feedback, appreciated.
Dave
There are UA-cam channels giving great insights into the industry. I am currently working towards my C&G level 2/3. I am finding this channel, Learn Electrics, to be the most useful in terms of knowledge and understanding; thanks for producing them and helping me to greatly develop my “mental toolbox”😊 …. Brilliant
Thank you martin, appreciate the comments. Lots more to come. Its a great trade to be in and its kept me busy for over forty years. Dave.
Another great video, keep them up👍
Thanks. Glad you enjoyed it. lots more to come. Dave
Excellent video.
Thanks Andy, your feedback is appreciated. Dave
Great content. Thank you
Glad you enjoyed it. Thanks. Dave.
Excellent content. I’ve paid lots money to an electrical training company, I’m learning as much if not more by watching your videos. Thanks for this!
That's good of you to say Martyn. These are things that your tutor should be showing you. Thanks for watching. Dave.
@@learnelectrics4402 They have/do... Just no way near as clear, concise, understandable and at such a maneagable pace.
Fantastic better than my lectures keep it up 👍🏻
These are the sort of comments we just love. We are so glad you enjoy them, we try our best to pass on information in bite size chunks. Keep watching and thanks. Dave
Great great video. I love your channel.
At the risk of sounding like an idiot I'm a little confused when you said energised electricity flows through r1 and then de-energised energy flows through rn.
I never thought of it in this way and I'll have to look into that more.
Thanks a lot for taking the time to do these videos. Your teaching style works really well for me which is really saying something
Thanks for the support, appreciated. Its like water in a central heating system. Hot water flows into the radiator and cooler water flows out. We don't lose the water, the water flowing back has given out its heat and returns to be reheated again. Thanks for watching. Dave.
This is a mint demonstration of the test thanks. It’s helped me explain this. Being autistic I struggle to explains how stuff happens.
Glad we could help. Spread the word, it all helps. Dave.
I love watching your videos, the way you explain things makes it so much easier to understand, far better than the tutors on my electrical course, please keep making these videos.
Thanks Stuart. Yes, I will continue to make these help videos. Spread the word, that helps. Dave.
Great video
Thanks for the positive comment, appreciated.
Brilliant! 👍
Thank you, appreciated. Dave.
Thank you Sir
Thank you Asad, much appreciated comment. Dave.
Another great video. Any chance doing a video on contactors and relays. On how they work?
A good shout there. Yes, your request has been recorded and we will look at doing one, brilliant idea, thanks. Glad you enjoy the videos, lots more to follow. Dave
I think videos like this should always mention which countries these things apply to. The physics is the same everywhere, but rules and also names are different. I never heard about "R1+R2 test" and it took long 18 minutes to realize that we simply call this test differently. And table with resistance limits allowed for particular fuses are also different.
Thanks for watching, appreciated. Lots more to come. Dave.
Thanks for the informative video. I have a Napit CPS assesessment in a few months time. And I remember reading in the comments of one of your other videos that you yourself used to be an inspector for a Part P if im right? What kind of things were you on lookout for with potential candidates? And also do I need to show the assessor Minor Works Certifcates with all r1+r2 and ze readings completed etc.. even for minor things such as socket from changes?
Thanks
G
Every assessor will follow a set guidelines but interpret these slightly differently that is why the video says to ask the assessor what he wants to see when he phones to arrange a visit to you. The video does list all the things he will want on the OFFICE slide and on the JOB slide, have another quick look George. Certificates, generally want to see EICs or Electrical Installation Certificates but do get all your Minor Works together. The more you give to him to look at the more he will know you mean business. The worst thing for an assessor is to be presented with just one certificate. Good luck and relax. Dave
Perfect.
Thanks John, thanks for watching. Dave.
Can you do a video on electricity being 'energised' and 'deenergised' like you mention here? Interesting stuff.
Yes, I've thought of that, I have the perfect analogy to use. Its on the list now.
love it
Thank you Wayne, we try our best.
Thank you can you plz do one for RCD trip time 🙏
Absolutely we can. It is already planned, lots of requests for RCDs.
Watch this space and we are glad you are enjoying the weekly videos.
Thank you very much.
Would using RCD or RCBO help resolving loop impedance test?
Different tests, for different reasons. We should always try to achieve the correct loop impedance figures by correct design of an installation. Thanks for watching.
Thanks for this clear explanation you explain this concept perfectly!
I was wondering what your thoughts are on short courses for adult learners? I am 45 but would like to change career. I understand that getting some work experience is key to doing the job safely. I was thinking of doing a domestic installer course and trying to get some work experience to build up my skills. Do you think it’s worthwhile? I am keen to lean and do a lot of hobby electronics already. Thanks Glenn
Thanks for the positive comments Glenn.
Up until Covid struck the country I used to teach lots of Part P, 18th Edition and Inspection and Test courses. They are good if you are starting out, especially for mature learners of which there are a lot. BUT choose your training centre very very carefully. Some centres promise a lot and leave you still wanting. I would recommend actually physically visiting at least 3 centres before parting with any money. What are the training facilities, how much practical is there on each course, what is the written syllabus, get a copy. You are looking for a centre with a high standard of teaching, an instructor who has been on the tools for many years, not just read it out of a book or doing electrics one week and plumbing the next.
I also taught and assessed for one of the big scheme providers and although they might be a little more expensive they do have a high standard of teaching and are in a much better position to advise on your next step, especially on registration as an electrician. They can be worth the extra cost and extra driving distance in the long run. As far as experience goes, some chaps have offered their services free as an electricians mate one day a week until they build up experience. Others just do minor work stuff, changing lights, repairing broken sockets etc. until their skill, confidence and experience build up.
You will get NICEIC and NAPIT phone numbers off the internet.
Hope this helps - be careful before you part with a few thousand pounds of hard earned cash. Dave.
@@learnelectrics4402 Dave thanks so much for taking the time to give such a detailed reply. This is great advice and much appreciated. I was thinking of this course at trade skills for you
www.tradeskills4u.co.uk/courses/domestic-installer-course
I am interested in later on doing the EV charging point course too. That’s all I want really someone I can work with on a Friday so I can learn. My issue is I wirk 4 days a week and I need to keep that going as I have a mortgage and children. Someone else from the industry had suggested doing an nvq level 2 with a view to doing level 3 and working on contracts but I think I would struggle to fit the course in round my job.
One thing that put me off years ago was I had been told I was colour blind. I have since done an online test and I have mild deutan or red green colour blindness. This doesn’t effect me seeing the colours of the wires at all there is no confusion between earth, live or neutral. Plus I have seen there are glasses you can buy to solve this. Do you see this an issue?
Thanks again Dave and sorry about the 2,000 questions.
Cheers
Glenn
Glenn, lots of sparkies are colour blind but there are many levels. Most don't know and it never affects their work. Don't worry about it. We have a video on this that might help.
Colour Blindness Testing
ua-cam.com/video/P0Cgglc391M/v-deo.html
As a trade you will need the 18th Edition so keep watching our 18th edition help videos.
You need as much practical as you can get so if it was me I would spend Fridays with another electrician learning the skills. Or even doing things in your own home. Change a socket, change a light switch. Make the garage lights two way. Invent things to do. Make a plan that every Friday you do just one easy job in you house. Change a ceiling rose. Fit a 13A socket with a USB charger socket.
Practice is the key. Good luck. Keep watching the videos, never stop learning. Dave.
@@learnelectrics4402 thanks Dave it’s funny after sending you the colour blindness question I saw your video on it it’s like you were reading my mind🤣.
Brilliant advice Dave I will definitely do that. I think I am just going to go for it with the course and practice loads and get some work experience with someone and as you suggested do work on my own house. And of course I will keep watching your videos. Thanks again for taking the time to reply.👍
Good luck, I've enjoyed the last 40 plus years in the trade, and most times the roof is on when you're working. Dave.
Hello Dear Tutor
I am your fans and watch your video long.
something I don't understand is near the end you said " if the circuit breaker changes to type C from type B, the Zs goes down. It is now even harder to get the figures and sizes become more critical and changing the type D breaker makes it worse again " however, as we know the less resistance on Zs, the more fault current will flow and the quicker the circuit breaker operates to trip. looking forward to hearing from you soon. thank you
That is correct. If you make the MCB less sensitive to tripping B to C to D you need to increase the current to compensate for this lack of sensitivity. Next Mondays video is about MCBs and more detail about this. Thanks for watching.
@@learnelectrics4402 Thank you for teaching the relationship of resistance and current for the Zs. but for the sensitivity of the MCB I don't understand that based on the changing type B to type C, the resistance is lower and the current should be risen, right ? for the typee of the rating 32 A, does type C have higher sensitivity than type B because type C has lower resistance value ? I don't get it, please help.
I have been asked why you can't take a zs and subtract ze to get your r1 r2 , my answer was because of parallel paths , but if your saying leave the cpc in the MET , you would still have parallel paths?
You will need the earth in the cpc to get your Zs. Your test meter won't work without. Thanks for watching. Dave.
@@learnelectrics4402 I don't understand your reply🤔 , you say take the line out the mcb and put it in the main earth terminal , the on site guide also says leave the cpc in and put a fly lead between line and cpc but surely this leaves parallel paths?
Is there a max vlue for R1+Rn The breaker must still trip safely if there is a short between live and neutral ??
Yes, but think about it. Most circuits have the L+N+E going the same route so they will be almost the same length.
As the Neutral is the same size as the phase, and the earth usually smaller, this means that R1+Rn is less resistance than R1+R2, so the short circuit current could be higher. Hope this helps buddy. Dave
We have a great video about this ... Cable Lengths and R1+R2 ... on this link
ua-cam.com/video/Qq_9MNH8XxU/v-deo.html
@@learnelectrics4402 Thanks, what you say makes total sense. Just we are never asked to check the R1+Rn to make sure it is less.
Stick with me buddy, we'll get you there. Dave.
Is Ze given by supplier or do you measure it also
The supplier will just give a general figure if you phone them and often nothing like the actual for that property. It is quicker and more accurate to measure it yourself.
what is the relationship between r1 and r2 recorded in step 1 and (R1+ R2) recorded in step 3.
little r1 can be a number on its own, and can little r2. But R1+R2 is an expression, a symbol if you like. There is no such thing as big R1 on its own in a ring circuit. Take a look at this video.
ua-cam.com/video/6Re2sqGVoWY/v-deo.html
Understand for telling me this it will safe my life
Thank you for watching. Appreciated.
Nice theory. But practically required with an MFT meter.
Absolutely. Always practice using an MFT. More practice, better skills, thanks for watching.
What about if the fault was on the neutral side of the resistive element?
If the fault was neutral to earth then you would not have an overload since the resistance of the appliance is still in circuit. You may find the RCD trips though.
Good question. Dave.
@@learnelectrics4402 not sure why I asked this as they're effectively the same by being connected at star point 😂
Glad you did Ed, someone else might have been wondering the same question.
And what a but if we have TT resisting will be very high MCB will never trip?
Thanks for watching, appreciated.
As it says in the video this is just for TNCS and TNS systems.
We are making a separate video on TT systems so please keep watching.
Lots more to follow. Dave.
@@learnelectrics4402 thank you I cant wait to watch a video a but TT disconnecting time.
Glad that you are enjoying the videos.
How measure R1+R2, of 3phase?
Three separate single phase readings.
Resistance affected by length, size, temperature and material
Correct Tony. But we are only looking at copper here.
Thanks for the input.
Dave.
is this not irrelevant when using 30 mA rcd 30mA is a lot less than 200A fault current and trips very quickly old regs V new regs
Good question. RCDs are additional protection, additional to that provided by MCBs.
I know what you are saying but we are just telling you what the Wiring Regulations require us to do. Lots more to come, hope you are enjoying them. Dave.
Another option if Zs is too high - Supplementary earth bonding
Thanks for watching.
so resistance is not futile???
Nice one. Thanks for watching.
OPTION 3 NOT SHOW ONLY OPTION 1 & 2 AS YOUR TALK
Option three is the table next to the see-saw where it says option 3. Have a look at 15:04 onwards. Changing the circuit breaker size. Thanks for watching.
Wtf is "de-energised electricity!!?
Think of it like hot and cold water in a central heating system Mike. Hot, energised water flows into the radiator, gives off its energy as heat and then flows back to the boiler as cooler water to be re-heated, re-energised, and flow around the system again. Hope this helps. Dave.
Great video
Thank you. Much appreciated comment. Dave