The absurdity of the Electricians trade

Discussion in 'Electricians' Talk' started by unphased, Oct 13, 2018.

  1. unphased

    unphased Screwfix Select

    If you consider the plethora of rules and regulations surrounding this trade and the amount of bickering amongst all professionals about testing, and of the importance of testing, there is one absurdity that sums it all up. There is no requirement to test the operation of an mcb! And no means of testing one available. So every single mcb fitted is never tested. It is all just accepted that they work. If only the faith exhibited in mcbs could be spread to other areas.
  2. retiredsparks

    retiredsparks Well-Known Member

    When was the last time you tested your
    smoke alarms

  3. peter palmer

    peter palmer Well-Known Member

    We do put a lot of trust in technology with ever knowing if its even real. Look at those mine detectors sold to the armed forces, nothing mall than golf ball collectors. You wouldn't be happy if you were using one of them and found out.

    Some of the Chineese MCBs didn't even have any working innards, just a piece of braid connecting one terminal to the other.
  4. spinlondon

    spinlondon Well-Known Member

    The thing with fuses and MCBs, is that they will work.
    They don’t need testing.
    RCDs on the other hand are hit and miss.
    Insulation can become damaged or deteriorate.
    Installations can be altered during their lifetime.
    Even the environment can affect things.

    Actually, you can test both fuses and MCBs.
    There is equipment available to conduct tests, but it’s very expensive, and testing either, would involve using dangerously high current.
    With a fuse, it would be no use once it passed the test.
    Last edited: Oct 13, 2018
  5. unphased

    unphased Screwfix Select

    Yes I was specifically referring to mcbs (BS EN 60898), I realise fuses with wires as the cut-out are use once. Also the RCD component of BS EN 61009 is the only testable part.

    You say they will work. Will they? Its a leap of faith for every single one. There are fakes out there as we all know. It is one of the hypocritical aspects of the industry that they make so much fuss about training, testing, registering, Part P, C&G and yet ONE of the most vital components of every single consumer unit and distribution board, the mcb, is never site tested. Once it leaves the factory its a leap of faith it will work.
  6. peter palmer

    peter palmer Well-Known Member

    To be fair I've inadvertently "tested" a few MCBs over the years when things haven't gone quite as expected.
  7. seneca

    seneca Screwfix Select

    Haven't most of us Pete!
  8. Comlec

    Comlec Well-Known Member

    I tested one only this week - using the side cutters on a live cable - oops
    seneca likes this.
  9. Comlec

    Comlec Well-Known Member

    In their wisdom the 18th requires RCD and RCBOs to now be tested every 6 months instead of quarterly. This will immediately half the number of test being missed but boost the sales of labels.
  10. spinlondon

    spinlondon Well-Known Member

    It’s not a leap of faith at all.
    It’s an application of scientific principles.
    Heat something up, it gets hot.
    Heat up something made of metal and if it gets hot enough, it will melt i.e. a fuse.
    An MCB uses a bi-metallic strip.
    Heat it up, it bends and the MCB trips.
    Neither the fuse or the MCB can do anything other than what they are designed to do.
    You’d have to fill up an MCB with concrete to stop it from working.
  11. MGW

    MGW Well-Known Member

    Yes I have tested MCB's, on a caravan site in the 90's a load of away workers were stopping on the site, and there was a 5 amp supply to each caravan, after the DNO fuse ruptured started to test them with a 2 kW fan heater with a 16A blue plug, simple go/no go, at 1 Kw they should not trip at 2 Kw they should trip swapped around 20 which on further inspection some were 15A with 1 scratched off, and some the setting screw had clearly been altered, all old LOADMASTER type. However that is only time I have checked them.

    The contract workers were taking their life in their hands changing and altering trips live, but only one death on site and don't think that was related to altering MCB's.
  12. unphased

    unphased Screwfix Select

    Another fine example of how much bull is printed in the Regs. Eddy currents do not exist.

  13. Pollowick

    Pollowick Well-Known Member

    Or even side cutter on a cable where the MCB is off, so just N & E, or even pulling the cable through a back box and the bare neutral touching the metal!
  14. unphased

    unphased Screwfix Select

    Of course it is a leap of faith. If you install an mcb in a CU you have no means of checking whether it will work under the conditions for which it is designed. Unless you can physically verify that something can operate then you are taking a leap of faith. Its the correct term I am using. I am sure that scientific principles are used in its design, but, scientific principles in design cannot be verified in action as unless you are prepared to spend thousands of pounds buying the equipment to enable you to do so, it is simply a leap of faith it will work when called upon to do so. An mcb is a mechanical device. Fuses are another example of having no real means of testing if it will work. I know it is based on careful design and in reality it is one of the few things we can take for granted because it is not mechanical, no moving parts and it is designed to fail. An mcb is mechanical. There are fake mcbs out there without any means of tripping, just pass current straight through. There are I am sure thousands of these things in use and no means of knowing.
  15. Coloumb

    Coloumb Well-Known Member

    Even if you could test them it's only as good as the moment it's tested. In the past I've come across RCD that will work when the button is pressed but fail on the actual test, or partially fail, despite passing the tests a few years earlier. Who knows when it actually failed?
  16. unphased

    unphased Screwfix Select

    Lol, you are a card. Only one of those items seem to appear in BS7671. I regularly test my RCD and smoke alarm though. It would be silly not to. Incidentally, the IET think that putting a label on the CU telling you to test an RCD quarterly everyone does? They surely must do if its labelled to do it? Imagine, a label can illicit such faithful and responsible action from the general public. "Whats an RCD?" is the most popular response. Call me skeptical but the IET are as naive as fairies in a pixie ring. The same ring that Risteard inhabits.
    Last edited: Oct 14, 2018
  17. retiredsparks

    retiredsparks Well-Known Member

    All those I mentioned are BS, BS-EN, or Kitemarked.
    It was set as an example...not as a inclusive list, mutually exclusive or limited to one publication.
    The "lol" behind the RCD was to infer that there is a 'label' on most boards advising testing....but in fact is very rarely done.
    I agree with you (yes, you did read it
  18. joinerjohn1

    joinerjohn1 Screwfix Select

    Lost of things are nonsense in life. Take your car for it’s MOT tomorrow at 9 am. Let’s say it passes. The MOT certificate only states that the vehicle passed the test at that time. Certainly doesn’t mean it would pass the exact same test 2 hrs later. ;)
  19. Bob Rathbone

    Bob Rathbone Well-Known Member

    No one on this forum has mentioned 'Back up protection'. For a simple domestic installation, the service fuse (100A!) is accepted as secondary protection in the event of a MCB not tripping. Try telling that to a piece of 1.0mm2.
  20. Coloumb

    Coloumb Well-Known Member

    Apparently you need the permission from the distributer for that to pop ;)

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