CIRCUIT BREAKER TYPES - How they work and inrush currents
This is an introduction to the selection of MCB types and how a knowledge of inrush currents at start up can influence the choice of device.
We look at thermal sensing of overload currents and electro-magnetic responses to short circuit and fault currents.
Should a type B or type C be installed, and what are the implications on safety and circuit performance.
And we also look at the different kinds of devices, single pole, three pole, four pole etc.
This video is a good overview of the subject.
You may also want to follow the link and view our video entitled - Zs too high What to do - on the following link
• Zs TOO HIGH What can I...
This video is No.71 on our KZhead 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 KZhead search bar.
Always work safely, electricity can be dangerous. If you are unsure, stop and seek advice.
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. kzhead.info/tools/YaJQnpO4XAp0yCgqzMkmfA.html
The explanation is at the Highest level of standards and second to none. Thank you Sir.
Thank you Asad, brilliant feedback, really appreciated. Dave.
An other brilliant video ,The man explains every thing very well as it is, and answers all questions from everyone !!
Thanks for your support Andy, very much appreciated.
Thanks again for the really useful information on circuit breakers. You've become my little "Go To" for electrical help, advice and clarity when im carrying out little projects now my dad has passed. Really appreciate your videos. Good work.
Thanks Kevin, really appreciate the feedback. Yes, my dad was always at the end of the phone when I needed him.
Best video I have seen on the subject. Thank you.
Thanks Alan. Really appreciated, gives me encouragement to make more. Dave.
Your tutorials are excellent, both with the visuals and the explanation of theory, please keep them coming. I don't know if you have covered this in a previous tutorial and I missed it but the use of different types of protective device to accomplish selectivity from cascading along different distribution circuits would be welcomed. In domestic scenarios where the main DB feeds a garage DB, which then feeds a shed at the end of the garden for example.
Olly, great feedback. No, not covered that yet - it's called discrimination and will be covered in the next week or two. It will be on MCBs, RCBOs and RCDs etc. It's a good topic. Thanks. Dave.
Great videos. I do follow you and I gain my knowledge with every video. Thank you!
That's great to hear Patrik. Every little bit of learning adds up over time.
This is exactly the information i was looking for. I had been wondering if my LED lights had a high enough inrush current to trip the 5 amp MCB but it seems it allows for the inrush.
So glad we could help. Lots more videos to come. Thanks for watching. Dave.
Great explanation Dave, thanks👍
Thank you very much. Glad you found it useful. Dave.
Another super well explained video.
Thanks Paul, I really appreciate your comments. Dave.
Thanks for the information, visual helps a lot
Thank you. Great feedback. Dave.
Thank you for your efforts.
We try, we do try. Thanks for watching, it is appreciated. Dave.
Great explanation..Thank you...
Thank you Alex. Glad you found it useful. Dave.
Fair play although I know most of the content of your videos, every time I watch one, the visuals help reaffirm why the knowledge is so important. Would love if you did an on site guide video explaining as above. Top video once again.
Thank you Mathew. Very true words, we should all keep learning and refreshing our knowledge. Great feedback, appreciated. I have made a note of your request and it will be actioned in the near future. Dave.
@@learnelectrics4402 hi Dave, please don’t do it on my account. I just really enjoy some of your 18th edition wiring regs ones and whilst watching them thought to myself I wonder how many important things in the on-site guide I don’t realise how or why they are so important. You are spot on continued personal development by continuing to understand the basics. 👍
Yes Mathew, the On-Site guide will be covered too. Thanks for taking an interest in the channel. Dave.
All videos have the best explanations possible. Even above the e5 group guys. Can you do one on design please.
Thanks Chris, yes, Circuit design videos are being considered. Dave.
Great video. Learning lots watching this. I will pas this in at college.
Please do spread the word, thankyou.
Thanks a lot for this.
Glad we could help. Thanks. Dave.
Thanks for uploading
My pleasure, glad you enjoyed it and thanks for watching. Dave.
Great video, thank you👍
Thanks Royston, your comments are appreciated. Dave.
What a great video!
Thanks for the fantastic comment. So glad you enjoyed it. Dave.
Great video! At B type, in that table, it is mentioned that it is for long cables. I guess because it has to do with a bigger Zs and a low PFC?
Longer cables mean higher resistance/impedance that C and D types might not meet. But if you can install a smaller size MCB say from 32A to 20A, you're permitted Zs increases. Thanks for watching. Dave.
@@learnelectrics4402 Thank you for your answer! Have a great day!
Great video
Thanks for watching. Dave.
Hi.. would you be able to do a video on what io , ir etc mean on an MCCB and why you would want to adjust them. Instead of adjusting why would you not just get the correct one
Good idea Jake, it's on the list.
🙏 thank you 😊
You’re welcome Ibrahim, Dave.
Sorry, I am a newbie to this subject but was drawn to it when researching what fuse size to use on an offgrid solar setup. If a 10 Amp fuse will not blow until it might reach 100 Amps, then what cable size should I be using, something that is rated for greater than 10 Amps or a cable rated higher closer to 100 Amps???
Its all to do with how long it takes to trip. Have a look at this video on the link below. It will help. thanks for watching and stick with it, its a good trade to be in. Dave. kzhead.info/sun/idiNhc-Np4NjhZs/bejne.html
What does I2 (current causing effective operation of the overload) mean? is it when it arcs temporarily and raises more amps?
Its the current required to cause the device to operate within 0.4 seconds. In other words, the current required to satisfy the Zs tables. Have a look at this video, it shows how I2 is used to calculate ZS. kzhead.info/sun/fM6peq9pnHyCra8/bejne.html
@@learnelectrics4402 Thanks again dude!
Does the thermal overload still work in a TT system?
Unless you can get enough current flowing to exceed the breaker rating by enough amps and enough time, then no. That's the problem with TT. If the fault current flowing in say a 32A circuit is less than 32A then it will never trip. Good question. Thanks for watching. Dave.
MCB provide earth fault protection??
Correct. Thanks for watching.
It is normal for main circuit breaker to be a little hot at time? Mine once in a while trip, I dont think my appliance is shorted as it could be reset. I think maybe it is too old, mine house is 25 yrs old, Ty
At 25 years you may need a Periodic Inspection by a competent electrical inspector.
Why this MCB takes 15 mins to trip for 52 amps in a 32 amps MCB type B ? Can you please explain
Have a look at the video again Amarnath. We explain in the video just why and also look at page 370 in the Regs book for Type B breakers. The table shows a trip time of 900 seconds for a 32A breaker if there is only 52A of fault current. 900 seconds is 15 minutes. Thanks for watching. Dave.
Thanks alot for this. I just had to refresh my mental toolbox 🧰 🔧
Great, thanks for watching Pabor.