MATCHING CABLE SIZE TO CIRCUIT BREAKER SIZE. How to select the correct sizes for safety and function
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- Опубликовано: 4 июн 2024
- How do we go about making the correct selection of fuse sizes, circuit breaker sizes and cable sizes?
We all know that incorrectly matched components can cause problems in an installation and that customers might complain of nuisance tripping because of a mismatch.
The fire brigade might also want to ask a few questions where they suspect an incorrect choice has caused a fire.
It is so important that all components in an electrical installation work together in achieving a correctly balanced circuit.
In this video we show you, in a simple and easy to follow sequence, how to understand the process of selecting the correct breaker or fuse size and, armed with this information, how to choose the correct conductor size.
Not only can incorrect choices lead to safety problems and unexpected tripping, a bad choice can also be expensive if the wrong size cable is purchased unnecessarily.
This short video will introduce you to the basics of cable size choice and help you to make informed and correct decisions in the future.
This is video No.63 on our RUclips 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 RUclips search bar.
SEE ALL VIDEOS - 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.
ruclips.net/channel/UCYaJQnpO4XAp0yCgqzMkmfA
Fantastic and educational. I’m 53 years young and enjoy learning this amazing trade. You give very practical real world advice.
I appreciate those comments Robert. Lots of folk start again in middle age and make a good living. Lots more to come. Dave.
Looks like I'm in your boat
It's scary to think that some one who is presumably qualified and experienced to sign off other work doesn't have a clue of what they are doing, to say it's illegal also is worrying, good content mate
I'm afraid there are those out there that need to watch you tube but probably never will.
Thanks for the response Brian, much appreciated. Dave.
This vid really benefitted me. Thank you
Glad we could help, you're very welcome and thank you for watching. Dave.
These vids are great. So very helpful. Thanks so much.
Great feedback, thank you so much and thanks for watching. Dave.
Your videos have been a godsend to me. I have just finished level 3 (8202). Now I have 18th edition to do soon. Thank you very much for the videos !!!
You're welcome Nat, so glad we could help. Lots more videos to come. Thursday's video each week is about the 18th Edition exam. Keep watching, keep learning, its a good trade and its taken me around the world several times. Dave
Dave, if I have to drive 200 mile to come to your class and learn from you I WILL!!! Just tell me where is your college! I spent at least 3 years in college and lot of short courses in London but never ever meet someone like you to explain easy and clear so people in every level can understand it so easy!!! I can not thank you enough!! THANK YOU SIR!!!
regards
Ali
Thank you Alireza. I don't do classroom teaching at the moment. Everything stopped with Covid and still deciding what to do. Keep watching the videos, I hope they are useful. Thanks for your support my friend, really appreciated. Dave
@@learnelectrics4402 🙏🏻🙏🏻
You're welcome.
Excellent video. Thank you again to you and your team for all your efforts. Regards.
Many thanks. Lots more to follow.
This channel is the best… you discuss real life problems precisely and accurately… can you do a video on SDP sizing and selection
I've put it on the list to be done Joel. Thanks for your feedback. Dave.
Brilliant as always
Thank you Alan. Great feedback. Dave
This content is absolutely fantastic and you should be up there with the highest views and subs but......you don't drive a Tesla to site and bombard us with ads and marketing.
I prefer you guys as you are....👍🤝
Thanks Mike, appreciated.
Another great Video!!!
Thank you Steve. Much appreciated.
Always informative.
Thanks for watching, appreciated.
Well exsplained dave 👍
Thank you Rod. Appreciated. Dave.
Super vids Dave.
Glad you like them Andy. Thanks, Dave.
Wow! This is very informative, thanks for sharing it with us. It worth it and the best tutorial on the topic for me...dl
Great feedback, just what we need.
Thanks Dave.
You're very welcome. Thanks.
Spot on again Dave. A*
Cheers Gary.
Excellent sir 👌
Thank you, great that you like it.
Thank you
You are very welcome Alex. Thanks for the positive comment. Dave.
thank you
Glad you liked it Mary. Thanks for watching. Dave.
Thanks
Thank you Andrew, thanks for watching. Dave.
Hi just curious u rounded the amps to 4amps so what made u decide a 6amp circuit breaker? Why not 5? Sorry that part just confused me
Thank you
thanks
You're welcome Jamal.
Thanks for explaining this again. But pls don't forget to do a clip on circuit breaker types and functions 🙏🙏🙏🙏🙏🙏
Thanks for the feedback Pabor.
Have you seen our video - Protective Switching Devices - link below
ruclips.net/video/IR2_9N7J4DY/видео.html
We have a video in two weeks about different types and applications of breakers and other devices. Hope this will help and thanks for watching. Dave.
@@learnelectrics4402 yeah, I've watch almost all your videos. Will be waiting, thanks a lot
Happy to help.
you are amazing
Thank you so much, I really appreciate your fantastic comment. It makes all the hard work worthwhile. Good luck to you my friend. Dave.
If the shower draws 39A wouldn't a 40A breaker be too small? Considering that it is a regular practice to size a breaker at 125% of the continuous load, or to only utilize %80 of a breaker's capacity?
These are the minimum sizes. Thanks for watching.
Hi , great video , however when you choose cable for Cooker circuit, you showed in your example shower circuit instead of cooker circuit.
My question is if it was actually a cooker circuit that would draw 7KW then woudnt you apply diversity before choosing the circuit breaker.
Once again thanks for the video
No, you choose the breaker size based on the maximum design current. Thanks.
@@learnelectrics4402 thanks for reply so where does diversity fit in all this? As it was a cooker circuit so definitly diversity needs to be applied, I am just abit confused thanks
Apply diversity to a 7kW cooker and you get about 22 amps, so a 20A breaker is not big enough. The Regs say that for a 7kW cooker a 32A breaker is usually appropriate. The same with an upstairs ring circuit - diversity says that the circuit will only use 6 or 8 amps so why does the book recommend 32 amp breakers. It's one of those mysteries of custom and practice that the boffins come up with.
Diversity is best applied to overall demand of an installation. Yet with domestic lighting we can apply diversity directly to the breaker size. Sometimes we just have to go with the flow.
Thanks for the question, at least someone is paying attention. Keep watching, lots more to come. Dave.
How i understand it is, we use the smallest permissible wire size to reduce cost, increase ease of installation, and easier interface with components.
That about sums it up. Why waste copper and money. Thanks for watching. Dave.
Hi Sir, how do we measure the cable length? Is it from the consumer unit to the intended switch or socket outlet? Thank you.
Between the two points of measurement. Usually this will be the socket outlet or switched line terminal at a ceiling rose.
@@learnelectrics4402 meaning to say the fixed point will start from the consumer unit right?
Please apart from this MFT instrument, which other instrument can be use to determine the resistance value of a cable for for a distance of 1m
You can use a multi-meter.
@@learnelectrics4402 Please I did you it and I had a wrong value. Thus an approximated value
👍
Thank you, thanks for watching.
At 8:38 " Lighting is assumed to be an evenly distributed load across the circuit " What does this mean ???
Several lighting points along the circuit. Not all at one end a cooker might be.
why is multiplied by 100watts please
Because the Regulations tell us to assume the worst case scenario of 100 watts per lampholder. If the customer decides to fit 60W or even 6W LEDs then that is safer. But we should not calculate for 60W per lamp holder just in case the customer fits brighter lamps. Have another look at the video, it is explained. Hope this helps.