BREAKER AND CABLE SIZES FOR ELECTRICAL CIRCUITS.
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- Опубліковано 3 сер 2024
- How to select the correct size breakers and cables for your electrical circuits. This video will introduce you to the steps needed to calculate maximum loads on a circuit; how to use charts to determine the correct circuit breaker for the load, and how to select the right size of cable for the job. Avoid the dangers of installing cables that are too small and give rise to fire risk, avoid over sizing cables and wasting money on excess copper; the right size matters. Use the tables to ensure that the circuit demands are properly balanced and will function safely and correctly. With just one easy to use formula, this video will enable you to plan jobs more efficiently with the confidence that it has been done correctly according to the Wiring Regulations. Once learnt, remembered for life.
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/ @learnelectrics4402
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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
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When you fully understand something it is easy to explain said Isacc Newton. Your explanation was simple and complete. Thanks
Thank you Chris. We really appreciate this feedback.
Dave
9 times out of 10, yt influencers give out incorrect information. This guy does NOT.. Excellent stuff sir . Sub from me
Thanks for the sub, really appreciated. Dave.
Finally someone has explained the actual calculation of what we were trying to learn 👏
Thanks for the great comment. Lots more videos to come, including more calculations. Dave.
@@learnelectrics4402 hi dave 👋today is Christmas day "so I'll bid you merry Christmas 🎅 "and a big thanks for your teaching videos " I've been in the building trade for nearly 40 years now? As a bricklayer ☠👻spent most of my time on sites 'but went self employed in 2000 ' I've learnt a little bit about electrics 'wired up a few sockets now and again? And normally had to get electrician to check it over ' 🤪but recently I came across your videos " and got interested in expanding my knowledge of electrics 'I've watched other videos of similar advice "but found yours the one that struck me the most ' its not elaborate or highly glifick "but some how it works for me?? Think it comes down to how someone can get a difficult scenario across ! I find your instruction easy to understand 😃I'm going to follow you deeper into this "and get more equated with this "wish you could of taught me years ago "🙈all the best my friend "have a good New-year 👍
I can't begin to tell you how grateful I am for these videos although I retrained 7 years ago as a older student know 53 they give me a much better understanding I am now confident enough to help some of the younger apprentices with issues or just show them your videos keep them coming matey 👍
Thanks Mark, brilliant feedback, makes our day. 53? Still got loads of life in you yet and yes, it is good to pass on knowledge to the younger electricians. Thanks again. Dave
Mark, Your just a young man, Im 66 and still going strong so dont worry about age mate.
@@angelofranklin1 66 that's excellent I just noticed I put 53 don't know why because I'm 55 🤣 tell me I'm going be OK 🤣
Thankyou described it in a easy to understand, in the past I have looked at books on electrics,and they made it sound so complicated, but with your explanation I got it straight away,once again thanks
Glad you liked it. Keep watching James. Thanks Dave.
You have saved the day once again mate.
I was sweating over this theory on a training course and its a relief to now understand it. Thanks to your excellent communication skills. 👏
Glad we could help John, spread the word. Dave.
Yes, I completly agree. Easy to follow through.
I've been looking for this for a long time now. Well explained, thanks a lot.
Great Pabor, glad it was helpful. Lots more to come, check out our other 50 plus videos.
What a video, great at explaining and making things more clear and easier to understand! Bravo!
Thank you so much David. We really appreciate your positive comments. Dave.
Master your videos are superb. I'm not yet an electrical engineering student but I'm about to be, watching your videos is pretty good for a lost sheep. After tons of research this piece just made my day.
Thanks Matthew, good luck with your studies. Thanks for watching and keep learning. Dave.
Thank you so much, your explanation is perfect. In class they gave us handouts stating the steps of finding the cable size with these Ib, In, Iz symbols, never understood the meaning of these symbols, and now that i viewed this well explained video everything became clear
So glad that it helped. Tell the rest of your class mates about us, it makes it all worthwhile to keep making more videos. Dave.
Fantastic explanation really informative. Completed a domestic installers course with a well known training centre and this is great to keep my knowledge from rusting up. Great stuff and easier to understand.
Thanks Robert, really appreciate the good comments. Dave.
i learnt more from you than from my 2 years at the college... keep the excellent work up
Thanks, will do Imran. That's fantastic feedback. Dave.
Love the video, the way it is explained is brilliant, grateful of the videos👍
Thanks for the really positive feedback. We try our best. Lots more to follow. Dave.
Thank you for this video, something what i thought id never get my head around made it very easy by watching this. once again thank you
Great to hear that Jess. If the video helped, its done its job. Dave.
Thanks a lot dude. Just about to complete my engineering apprenticeship and now wish to base my career from an electrical bias. These theories aren't so intimidating when broken down and structured as well as you have demonstrated here 👍👍 will be sure to watch more. Thanks again
Thanks for the feedback. There is access to over 200 videos on the website LearnElectrics.com Dave.
Thank you so much for the lesson. It was so easy for me to understand the way you explained.
Brilliant. That's exactly the feedback that we want. One video, one topic, made easy.
Lots more videos on the way. Dave.
Hi Dave, I recently completed and passed an excellent domestic electrician course at EC4U in Ditchling. Your video series is a superb “old-school” reinforcement of these key principles and in some cases has offered an even clearer explanation, or at least a different perspective on the same learning points. Being an older learner who has recently changed to the electrician career, this series has been brilliant. Thank you!
Thank you Mike for the very positive feedback. Our aim is to produce videos that tackle just one subject each week and they are based on all the questions and difficulties that electricians and learners have had over the years during the time that we ourselves have been working on the tools and as assessors and instructors. There are many more to come yet, keep watching and thanks again. Dave.
Mike.
How about the Domestic Electrician course in EC4U? I also want to join it.
@@hingninwong yes, look them up on google. The website is easy to navigate. Good luck!
@@MS-Patriot2
does the domestic electrician couse fit your purpose, such as capable for you to do the minor electrical work ? Any comment to this course?
Again very well explained. totally at ease with the way you explain things. very well done
Thanks Iqbal, great comments.
Thanks Dave, your a Legend loving all of your video
Have a great Christmas & take care
Thanks Johnny, thanks for the support and have a great Xmas yourself. Dave.
Its great the way you simplify it by using that box method,really helpful.
Thanks Marc, appreciated comments. Dave.
A fantastic help. Thanks for the video!
You're welcome. Thanks for the support.
Again an excellent video and thank for the great explanations.
Thank you. Glad that you are finding them useful. Dave.
Great video, very well explained, clear and to the point. Thank you very much
Glad you enjoyed it, thanks for the support.
Thank you so much for these valuable videos. Much appreciated 🙏
Glad you like them Aleko. Thanks for watching.
Excellent video. I learned a lot about choosing the correct wire size and fuse to be used.
Thanks. If the video helped then its done its job. Dave.
Very easy to understand. Great video. Cheers
Glad it helped, thanks for watching.
Hi Dave, very well explained thank you.
Thanks Angelo. Thanks for watching.
If i am not wrong, there is not even a channel like yours...
It is helping me...
Thank you for everything and may ALLAH(GOD) bless you...
From Mozambique
Thanks Mohammed. Thanks for watching and I'm so glad the channel is helping. I have some very fond memories of my time in Africa. Beautiful country, amazing skies. Dave.
Thank you for the breakdown it always helps when it’s explained correctly. Please keep up the good work you have my full support. Regards Karamat Hussain
Thank you so much Karamat.
Great comments.
Dave.
Love it! Thank you once more
Thanks for watching.
First video I see from your channel, amazing 👏. Thank you for your content sir.
Keep watching, lots more to come. Thanks for the comments. Dave.
Just wow this video is gold
We're glad you like it. keep watching, more to follow. Dave
Dear your explanation was so simple and it is delivering your experience. thanks ......
Thank you. Great feedback, appreciated. Dave.
Thank you for your excellent video.
Great comments. Appreciated.
Thanks once again for well presented technical material in the subject of electrical calculations
Kindly keep them coming
Thanks
Thank you, I will, lots more to come. Thanks for watching. Dave.
It's very important idea and concept about Electrical Engineering
Thanks for watching. Appreciated. Dave.
Very clear and easy to understand 👌
Great. That's exactly what we wanted to achieve. Thanks for watching. Dave.
you're the great explainer.
The great explainer, sounds like a song. Thanks for the great feedback, really appreciated. Thanks for watching. Dave.
Thankyou really clear and easy to understand
Glad it was helpful Paul. Thanks for watching.
Thankyou really good and clear to understand.
Glad it was helpful paul and thanks for supporting the channel.
Thankyou for your amazing video.
Glad you enjoyed it, thanks for watching.
another great video, i did miss the normal couple practise questions you put in though.
This is an older video, before I started doing that. Thanks for watching. Dave.
Boss explanation this is.
Thank you for explaining this better than the big book! It's quite a simple theory, made incredibly confusing and baffling by the wording in BS7671. I don't know why they don't just print the formula in BS7671 instead of the 3 bullet points.
Unfortunately we have no control over how the boffins lay out the book. Glad it helped. Dave.
Really really good video, thanks,
Glad you liked it. Thanks for watching. Dave.
You made it simple for us...
Great feedback, appreciated. Dave.
I've done 3 years of evening college, honestly wish I'd come across your videos first.
Well, you've found them now. Stick with it, it really is a good trade to be in. It's taken me around the world several times, worked in some fantastic places. Dave.
Perfect thank you
You're welcome Coby.
Great ,subscribed.
Thank you Stephen, much appreciated. Dave.
❤fabulous video ❤
Glad you enjoyed it, appreciated.
Well done again...
Thank you, thanks for watching. Dave.
Thanks for sharing it with us
My pleasure Daniel. Thanks for watching.
Brilliant thanks
So glad you enjoyed it. Thanks for the positive comments, they do help. Dave.
LOVE these
Glad you like them. Thanks for watching.
Wow! This is very informative, thanks for sharing it with us. It worth it and the best tutorial on the topic for me...dl
Glad it was useful.
@@learnelectrics4402I am here again
Great information
Thanks for watching, appreciated.
Thanks really perfect
Thank you, great feedback, appreciated.
First of all I want to say thanks a lot for all
Your excellent video. I would like to ask about 3 phase circuit how we can find out about Ib and cable size .
Thanks for watching, glad you found it useful.
We will be posting a video soon on 3 phase cable sizes, lots of people asking for information. Good request. Dave.
I'm glad to get ur channel sir,10Q
Glad that you lie the channel Aeneas. Lots more good videos to come. Dave.
NOT , I'M NOT LIE U. I swear.
Very good explanation
Nice comments, thank you. Dave.
Thanks for help
Always happy to help Reza, it makes the world go round. Dave.
Love yr video's can you please make a video on two way lighting circuit and fault finding if the wire's mixed up on celling rose and the switch thankyou
We have lots of videos on all aspects of lighting on our website.
Go to LearnElectrics.com and put lighting into the search box and you will get a list of all the videos about lighting and direct links to the videos.
Hope this helps, thanks for watching.
Have a look at lighting Differences on this link
ua-cam.com/video/NEjCXO_ZC5c/v-deo.html
Thank you once again for a very clear explanation.
Just one question:
8:28 you select the second row - even though I can see 6 rows with "100" as Allowed installation method (5 with 32 A breakers)
Is this because the top 2 rows are for breaker type BS EN 60898?
Could I also pick the 3rd row? (i.e. a 10mm^2 cable)?
Thank you for your patience (I hope this question helps other students).
Happy to help. Thanks for the feedback.
I think it’s worth mentioning that when you’re calculating your design current, if it is a 3 phase system you would put root 3 at the bottom of the fraction and if you have a power factor you would put Cos(power factor) at the bottom of the fraction aswell
Excellent information, thanks for contributing. Dave.
Brilliant
Thanks for the feedback. How is good old Shropshire, I lived in Shrewsbury for 20 years before heading south for the sun. Thanks for watching. Dave.
Thank you
Thanks for watching, appreciated. Dave.
Hi Dave, another excellent video, we all thank you for all you are doing. I'm confused about the choice of cable size. On the chart on page 72 I see many entries with a rating of 32A that fit with the 100 installation method, why did you say there is only one?
Also, do you know where in the book we could find the installation methods? Again, thanks for what you are doing.
You will find installation methods begin on page 433 of the Wiring Regs book.
If it is flat profile twin and earth we choose the nearest size cable equal to or greater than 32A which is 6mm. See Table 4D5 on page 456. Hope this helps. Dave.
Brilliant A1
Thank you. Great comment, it makes our hard work worthwhile.
Im training as an electrician and your videos are very helpful, i can see this calculation wiuld be good for an individual radial or ring say for a shower or cooker, how would this woek with lighting circit or socket? I am starting my NVQ level 2 in september so sorry if this is a basic question.
There are standard sizes that we usually use for each type of circuit. The important thing is that the cable capacity MUST be equal to or greater than the fuse/breaker rating. I'll be doing a video on this soon. Stick with it, its a good trade to be in.
Really useful videos for someone learning the trade.
With regards to choosing the cable size, I'm just a bit confused, could you also choose the 10/4 mm too seeing as it also allows 100 as the installation method?
You can always go up in cable size, the difficulty might be in getting the conductors to fit in the accessory. Thanks for watching. Dave.
@@learnelectrics4402 Ah, I get it....thanks for answering
Fantastic video. What would change in the calculations if it was on a tt system. ?
Nothing should change. Install conductors with sizes as if they were in a TN-C-S system. They still have to take overload currents. Its just that your measured ZS will be all over the place. Dave.
Fantastic video again thank you, if you were installing a domestic cooker circuit for a 16.5kw cooker and induction hob (very large i know) how would you go about that?
Would you install a 16mm cable that would be able to handle the full maximum load of 67amps or with diversity included would say a 10mm cable would be sufficient?
Installation method ref method c no insulation and 8 meters of cable for the circuit
Sometimes these scenarios confuse me a little and i don’t feel 100% confident with selecting the correct size cable.
Any help would be greatly appreciated thank you
Thank you for watching and the great comment.
We have a video that will show you how to calculate diversity for your cooker.
The example in the video is for a 7kW cooker, just change the necessary numbers.
Cheers, Dave.
To view the video, DIVERSITY and MAXIMUM DEMAND, click on the link below
ua-cam.com/video/TV2IZtmydm4/v-deo.html
@@learnelectrics4402 thank you very much your videos are extremely well presented and helpful keep up the great work
Thanks again. Happy to help. Dave.
Thanks useful video. For the video of playing at 8:57, may I ask why not choose cable size of 10mm/4mm?
See above.
Seems easy enough as you explained in great detail, I am looking to install panel heaters in my flat, can these just be added to ring main or need a separate circuit, if a separate circuit then can I do myself to save money?
Consult the heater manufacturer's instructions. Some say that they can be plugged in, coming with a fitted plug is usually a good clue. Other heaters are recommended on their own circuit.
Adding a new circuit assumes that you are competent and can notify the work to LABC afterwards. Only you will know if you can do this. If you are unsure, I would suggest using a REGISTERED electrician, but ask to look at his registration card (NAPIT, NICEIC etc) before giving him/her the job and before handing over any money. Tell them you want a Building Control certificate when the job is finished. And get three written quotes before making a decision.
@@learnelectrics4402 thanks, the heater doesn't come with a plug, needs wired in to a fused switch
Thanks nice
Most welcome, thanks for watching
Thanks
Thank you Maryam, appreciated. Dave.
Hi
Thanks for good clips . I am a bit confused though When I calculate for 63 meter 6 mil cable the voltage drop will be 14 volts which is over the allowance voltage drop . example in this clip according to table 7.1 onsite guide
(7.3*30.43*63)/1000=13.99voltage drop which is more than 11.5 volts allowance
Thanks for your prompt reply. In your video, you said you choose 6mm cable is based on method 100 in 2nd row, but 3rd row also has method 100. So may I ask to explain more by based which Wiring Reg. , we should choose 6mm but not 10 mm cable? I have confusion to choose one between them. Thanks.
You need to look at all the information on each line. With 6mm cable the maximum cable length is 63 metres which is more than long enough for most domestic dwellings and this matches up with the rest of the information on the slide. If you install 10mm you can take the length to 105 metres. Hope this helps.
@@learnelectrics4402
Yes, i got it that based on the length of cable for the house dwelling in this case. Thanks.
A 6mm cable (6 sq mm) is fine when the insulation stays the same and the shower remains at 7000 W. A 6mm cable is near the limit. The user may well fit a 8000 W shower when a 7000 W shower becomes unavailable on replacement by a plumber. Or the insulation is upgraded. On balance I would install a 10 mm (10 SQ mm) cable.
Thankyou
Very welcome. Thanks for watching. Dave.
hello Sir can I ask what book you use for the tables amd charts you used in the video? thank you in advance
Hi Dave, could you do a similar video for three phase?
It is planned Ed. Thanks for watching.
Thanks for good explanation
But I need that book
Thanks for the good feedback Justin.
The book is the IET On-Site Guide 18th Edition.
You will get it from Amazon or google search it or even Ebay.
MAKE SURE that it is the BLUE 18th EDITION copy.
Any other colour will have different data on some pages and different page numbers and is no good to you.
Good luck, and thanks for watching. Lots more videos to come. Dave.
Thank you for the video. What is the difference between "rating" and load" in the table on page 64. Is this assuming diversity of 80% e.g. the shower is off for at least 12 minutes in every hour of use?
Load is the amount of current you put through a fuse. A kettle might put a load of 13A on the circuit.
A table lamp might have a load of half an amp
The rating of the breaker in the consumer unit might be 20A or 32A if a ring
Hope this helps. Dave.
thank you so much for clear clips. can I ask you if we have 63 meter cable length and use voltage drop formula vd={(44/6)*63*32 }/1000 the result will come to 14.7 volts and because its greater than 5% allowance means 11.5 volts is it acceptable ?
A 14.7 volt drop isn't acceptable as its above the values in the Regs. You would need a bigger cable size. Dave.
Is this an alternative method to using the 18th Edition BBB and using the design current x length of cable x mv/A/m x any grouping factors?
This video is about Ib In Iz. Condition factors are covered in a different video.
Thanks for watching. Dave.
👍👍
Thanks Mike, thanks for the support. Dave.
Hi great video but ai am confused you say at 8:32 there are 2 entries for 32a when there are 9, & 6 of them meet the installation method 100.. am I missing something obvious this is a little old not as page 82 now.. your help here would be most appreciated.. Thanks
👍👍👍
Three thumbs, that must be good. Thanks for your support, much appreciated. Dave.
All the page no have been changed in new on side guide and also length of cable is also changed on this video now new length is 46m and page no start from 74 to 85. You need to amend this video please.
M happy
Thank you Terrance, appreciated. Dave.
ETAP design and simulation software has already been introduced long back merging formulas, considerations, conditions,standards and requirements.
It has Mohan, but unfortunately its not allowed in an exam. Thanks for watching. Dave.
Hi - when you say IN must be the same or just above IB, how do we quantify or calculate 'just above' ?
If Ib is 9.9A then you want a 10A breaker. If you put a 40A breaker in circuit that is too big.
Could you plz do a video on SELV AND PELV circuits?
You must be a mind reader. That video is planned for February.
Keep watching, thanks. Bux
@@learnelectrics4402 lol
Can you explain the digital scale on a multimeter for measuring resistance? The only thing I can find is a old vid from perkies talking about ohms scale?! Many thanks do you have an e mail I like to talk about the course I’m doing !
Thanks, I've put this on the to do list of videos. Dave.
What if 3 shower is installed for single 32amp circuit breaker? Will it be ok?or do we need to recalculate
Definitely not ok. Every shower should be on its own circuit. Putting three showers on one breaker will contravene the Wiring Regulations, contravene the Building Regulations, contravene the Electricity at Work Regulations and contravene the Health and Safety at Work Act. That's just for starters, you will also invalidate any trade insurance you have and any professional indemnity insurance and invalidate the buildings insurance.
I’m confused, on page 72 for cable sizes you say there’s only one that matches the reference method 100, but there’s actually two? 32 amp 6mm and below it 32amp 10mm?
Also is there another chart that goes higher than 40A on page 64 ?
The two 100 references are for different cable lengths - 63 metres and 105 metres. A longer run will need 10mm cable. Fuses/breakers above 40 amps look at pages 61/62/63 in the Wiring Regs. That's a good point, perhaps I should do a definitive list for all fuses/breakers and put it on the website. food for thought. Thanks. Dave.
Hi Dave, When you mention @3.23 "larger cable " "paying for extra copper that you do not need". Is this the only reason? Will a larger cable not affect anything else, only cost?
A larger cable will carry more current more easily and will not heat up at the same rate as smaller cable sizes, We can always install bigger cable and know that we will not have a problem, except perhaps with getting the cable into the terminal holes, 10mm shower cable will work for a lighting circuit but no way will it fit in the switch (an extreme example, sorry). So yes, that little section comes down to cost. Good question and thanks for watching. Dave.
Hey Dave just a quick question if the shower is taking 30amps on a 32 breaker but the cable rating is 34 so is that mean the shower is taking 34amps? Which will trip the breaker?
The cable can take up to 34 amps but the actual current in the cable depends on the load.
A 1 amp bedroom lamp pulls the same current through a 10mm cable as it does for a 1mm cable - about 1 amp
You do some great videos Dave and explain things really well but I think this method is incorrect.
Table 7.1 of O.S.G assumes a max load of 26A for a 32A 60898 breaker where your shower has an IB of 30.43A.
I have always used and taught cable calcs using the tables from App' 4. Keep up the good work though Dave your explanations are great.
👍🏻
No Dave, the video is correct for a dedicated shower circuit, nothing else on it. Are you perhaps looking at maximum length for a 32A Type C breaker which is 26 metres due to Zs limits? Great comments and support. Thanks, Dave.
@@learnelectrics4402 Dave could I private message you tomorrow about this?
By all means Dave, yes. There is also another table in section 7.1 that states assumed maximum is 26A, but this is not a :Should not exceed: value and has been used for cable length calculations. The Electricians Guide to the Building Regs also states that a 7kW shower can be installed on 6mm cable with a 32A breaker. Dave.
@@learnelectrics4402 how do I contact you?
Dave, I looked for you under DavePotter on Facebook. There are six, which one are you? I was going to send you a friend request. Or you can send a friend request to FB for LearnElectrics or Dave Buckley. My profile image is me with a blue jumper and the union flag in the background. Speak soon buddy.