Types of MCB / Circuit Breaker, BCDKZ

Different types of circuit breaker, tripping current and considerations when using them.

[jamie_d___]

I love Electrical information, I enjoy it so much I'm watching this at 4.22am In Australia, before going to work in the electrical industry, purely for enjoyment . This is me coming out, as a geek .

[johnjgcork]

Thank you John, as always I learn so much from your presentations. I teach physics to Electrical apprentices among others in various career paths, but I find many apprentices have no real desire to grasp the science behind Electricity. I recommend your site to many. I always hope they learn as much from from us, to improve their own safety as much as the end user. Keep up the good work.

[Marcel_Germann]

Thank you, that video is great!
In addition:
In Germany there are two other types available. You've already mentioned the type K, this was a common type here for workshops with large machines. K stands for Kraft (power), and is one of the old german types still available. The other ones were:

H for Haushalt (household), manufactured until 1976. Magnetic: 2 to 3 times. Thermal:

2.1 times (up to 4A)
1.9 times (6 to 10A)
1.75 times (12 to 25A)
1.6 times (more than 25A)

So it's for high impedant grids. It was replaced by type L, which was used here until 1990 before it was replaced by type B. But L is still available as circuit breakers for the replacement of Diazed fuses. In this case the housing is round and it's having an Edison thread.

L for Licht (light), or later Leitungsschutz (cable protection): Magnetic is the same as B, thermal is the same as H.

Picture of a screw-in MCB with Edison thread:

[enycenyc]

+John Ward 2 related Areas worthy of Further video in my view:-
(1) When is a circuit a distribution-circuit that may only require 1sec (TT) or 5 sec (TN) disconnection time [>32A ?]. [presumably the TT case is where you also use a 100mA S-Type RCD as well...].
(2) Selectivity between MCBs
It seems, in some circles to be accepted to use a C50 to feed a downstream B32 (e.g. submain to garage with electric-car fast-charging-point), and similarly to use a C32 to feed downstream B16 (e.g. feed to outbuilding with multiple socket-circuits).
HOWEVER this is seemingly not 'guaranteed' and depends on the particular combination of devices and the exact fault-impedance and so-on and so-forth.
When is a switchfuse with BS1361/DNO style fuse instead of a circuit-breaker better to feed a submain, anyway...?
Discuss: What MCB-selectivity is actually 'good enough in practice', what 'passes inspection', etc...?

[johnmac]

Another great video JW, I was a bit hazy on MCB types, but you just nailed it

[bobbyleigh]

What a fantastic video. Thank you so much for this John. very informative and very well broken down and explained. Great work :D

[Sarcastix]

Very informative. I'm studying Electrical Engineering in college and we went over cable sizes for circuits but didn't discuss the impedance of the circuit.
So my understanding is you would need to have the correct size cable for the rated current but you might also need to increase the CSA to bring the impedance down to the levels specified in the guide to ensure magnetic tripping in the time allowed. Of course that doesn't really help if the circuit is already installed.

[ianm]

Only ever retro fitted type C twice, may years ago.Once when I added 4 more magnetic powered halogen lights to an existing circuit of 8 lights. The breaker would occasionally trip when the 12 lights were turned on. Changed to type C for this circuit and all was fine. Should really swap back to type B as over the years many of the in ceiling transformers have been replaced with modern electronic units.2nd place fitted was house entry lighting circuit. When using ye old tungsten bulbs the cold air rushing in from front door would mean very short life for the entrance hall way bulbs, generally bulbs blowing and taking out the breaker. This circuit was also the garage light circuit where the breakers were located, as well as any easily accessible light switches from front door. Thus one had to fumble around in the dark, in the garage to reset the breaker. Changing this to type C meat when bulb blew the breaker no longer tripped and other lights on the circuit worked fine. All not necessary now using first CFL bulbs and now LED.

[aogulla]

Nice video. A brief mention of DC circuit breakers and why AC breakers should not be used in DC circuits would be helpful.

[richardlang]

Dear John. Thank you for making all those great videos. You have great electrical knowledge and I do very appreciate it. I need to mention one comment. BS7671 doesn't provide final Zs values for Circuit Brakes. All values have to be multiply by 0.8 correction value. On Site Guide have already corrected those values compared to BS7671. Kind Regards Richard

[aroncells]

Great video, your knowledge and ability to teach this is very appreciated thanks

[johnmac]

If you could do one on RCD types as well (if you haven't already?) that'd be great, thanks JW

[manickn]

Excellent video. This was on my to research list so I saved that time watching the video.

[gbelectricks]

Great explanation again John. Please could you do a video on mccb’s. Thanks

[bborbelyimre]

Dear John, this video is graet. Regards, from Hungary

[IrishHitman]

Very informative... Any chance you could explain with Ib and In etc... rated current and breaking capacity mean while you are on the topic. Thanks.

[CoolJoshk]

Can you do some vids about surge protectors?

[islashiraz]

Thanks Mr ward for all of your informative videos, without watching your video, I couldn't progress in my electrical installation course. Thanks again

[uittyman]

Great content your a beam of electrical light for the curious mind. An enthusiastic thumbs up 👍

[mayureshpatil]

Very nice & Crystal clear VDO. Can you please explain why MPCB used in Industry and disadvantages / Advantages over MCCB's.