Choosing the Right Circuit Breaker - 6kA vs 10kA
In this electricians' Q&A video, we delve into the world of circuit breakers and uncover the meanings behind the specifications printed on them. Have you ever wondered the difference between a 6kA and a 10kA MCB? Well, wonder no more! We'll explain what ICN means and how it's related to prospective fault current ratings. We'll also explore the regulations surrounding installing protective devices, including the importance of measuring or calculating the prospective fault current.
Joe Robinson will guide you through the three options for determining prospective fault current and provide practical examples for measuring or calculating it. Plus, we'll reveal why devices rated higher than 6kA are sometimes necessary and the specific criteria that must be met for domestic installations.
Want to learn more about circuit protection check out this FREE CPD training module
👉training.efixx.co.uk/course/c...
Want to learn more about circuit protection check out this FREE CPD training module 👉training.efixx.co.uk/course/circuit-protection-devices
Not a complaint, just an observation. I love your channel and Mr Robinson is an absolute star in my book. On this video the sound is low and woofly, not the usual eFIXX standard. Thanks guys.
Great video again. I have only ever come across this problem twice before. Once in a training college and the other was in a Domestic installation. In the 40+ years in the trade, only a handful of Electrician's would even had known this. In my personal opinion. Most would always fit what the wholesaler's had on the shelf. Same with type of MCB'S. Whatever the wholesaler's have on the shelf. Maybe, something for the industry inspector's to check and give advice, on there annual visits.
Great video as always. It would be good if you produced content on back up protection when set fault levels for particular ocpd's are exceeded
Great Video. Should Ipf be calculated using Cmin?
If you're close to the transformer the highest short-circuit current will often be through line to neutral and not the 3-pol short-circuit current.
Why?
@@ppdan I think it is because the impedance will be lower close to the transformer if you have 1-pol compared to 3-pol.
@@Faddnn Line to line has a higher voltage than line to neutral and according to ohms law a higher voltage will induce a higher current into the same load.
@@ppdan It is not that simple when you are close to the transformer. If you want a complex answer you have to ask someone else. All I can say is, this is the situation when I get the numbers from the DNO when working on projects close to a transformer (TN systems).
I always test and never enquire but phase-phase SFC is often higher in commercial 3 phase than phase-earth or phase neutral. That's because earth and neutral are both the same at the transformer where phase - phase is the greatest difference in potential. Often I'll find Phase-Phase around 9.8kA where Phase-Neutral/Phase-Earth will be around 3.7kA
Your channel is very useful not only because of high quaility, but also because it's more relevant to European electrical distribution. There is a lot of US electrical content out there
Could you reupload this with louder audio? Something went wrong and I can barely hear what you're saying without cranking the volume up.
Nothing wrong my end.
Nor me
I assume this is similar to the AIC rating we have over here in the US? We go with sequential order... where we get with our utility company with our load demands and determine the AIC rating of our Main breaker depending on other things as well as wire size and length. From there the other breakers after the main step down in rating so as to not trip the main unnecessarily when a ground fault happens in a sub panel. I.E. ... the fault should only trip the breaker feeding it and not bypass (let's say) four breakers ahead of it and trip the main. ...Simplified explanation
What about in commercial premises?
The Ze value where 10k is required would have been informative 👍
V =IR therefore v/I will give you that value. 230/10000 = 0.023 ohms. But you also need to consider short circuit loop impedance.
Even if you measured 16KA PSSC at your main switch, a BS88 80A service fuse would clear the fault by 3.8KA.
We use Rockwell Allen Bradley 💯
Isn’t that through fault current reduced or limited by the first CPD ?
Backup protection
Testing the highest value of SFC/ PFC down during inspections is more important on 3 phase installations than on single phase where enquiry is acceptable. That's due to the voltage difference of line-line, if you're at 400 volts phase to phase / phase to earth with 0.04 ohm ze you're at 10kA. I've had it before where you've enquired and the DNO aren't even aware there's 3 phase in a property. Also the number after the 6000(3) or 10000(3) is the number of times the breaker is rated to trip without issue if my memory serves me correctly.
No the 3 means it's an energy limiting class 3 device. Single phase or three phase it makes little odds of the device isn't up to the job.
@@travoltasbiplane1551 Well my memory isn't perfect after all these years but I do remember there was a number on devices referring to it, though I am going back many years since my NICEIC inspector informed me. It's probable that it isn't even needed on these modern devices.
@@effervescence5664 you're thinking of the ics value, which is max breaking capacity where the MCB can be safely reused, icn is the max one time breaking value.
That 16kA conditional rating is all well and good... Bet those domestic installations are gonna still be using t&e though... K2s2 isnt gonna be up to thr i2t of the device.
Can you guys do a video on using programs for calculating wire dimensions? A bit selfish but I have a sense that I’ll be able to pick up some new knowledge. It’s a interesting part of installation that most, at least Swedish sparks, have a limited understanding of.
R=(ρl)/A Do you really need a computer programme for that?
@@deang5622 I’m thinking about the dimensioning of cables from distribution boards and taking voltage drop and other factors in to the equation
@@kristiangoransson6104 And voltage drop depends on the electrical resistance. I provided you with the formula to calculate that electrical resistance.
@@deang5622 I’m not stupid but doing calculations manually for a freezing faculty with 6000A three phase isn’t very financially viable. It would be interesting to see how British sparks or consultants do it since it seems, at least on KZhead, that you do more measuring and documentation than we do
@@kristiangoransson6104 It isn't that you are stupid, it is that electricians are not taught the fundamentals. And that is what is wrong. They don't teach it, and they should. Ok, there is partly a problem that they take students on to electrical apprenticeships that don't have strong enough maths and physics skills because they don't set any minimum requirements in these topics, which of course they do set if doing an electrical engineering degree. Figure that out!
Why do we see so many 6ka and 10ka breakers then? Surely if it could be up to 16ka all breakers in new installations should be 16ka ?
Because the devices are cascaded with the upstream device. There is backup protection. The energy let through of say the supplier fuse will help the downstream device break the fault current. Essentially it will never see the full 16kA.
@@travoltasbiplane1551only for a consumer unit though, which is type tested by the manufacturer. That's where the only OEM mcbs in their board comes from.
@@matthewthomas6121 yeah I think the exact wording is an assembly to 61439
The prospective fault current tend to decrease due to the increasing impedance as you go down the network. For my country, we follow the guide of using 6kA for up to 15kVA, and 9kA up to 23kVA.
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