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Thread: Home electrical safety devices

  1. #11
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    6.8.1 Circuit-breakers used as main or local switch-disconnectors
    A circuit-breaker that is used as a main or local switch-disconnector (see 6.9.4) shall comply with the relevant requirements of a standard given in clause 4 for switch-disconnectors, or, alternatively, a switch-disconnector shall be positioned on the supply side of the circuit-breaker.

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  2. #12
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    Why does he need to add a circuit breaker ? He replaced the old RCCB with a new RCCB ... and the RCCB acts as the local switch disconnector

  3. #13
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    I'm not familiar with the term RCCB. If an RCCB is an earth leakage disconnector with an integrated circuit breaker, then that will suffice.
    If it is an earth leakage disconnector with no integrated circuit breaker, then a circuit breaker must be installed on the load side of the earth leakage disconnector.

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  4. #14
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    Quote Originally Posted by BobZA View Post
    Why does he need to add a circuit breaker ? He replaced the old RCCB with a new RCCB ... and the RCCB acts as the local switch disconnector
    Yes he needs to add a 63a mcb before the RCD as this unit does not have overload protection if he had installed a RCD with oveload protection then it can be used as a main switch at the moment there is no overoad current protecting the 16mm incoming cable except for the council kiosk.

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    If you want to use Lear as jou have then the unit you need is the one in the picture. I am not very fond of the Lear units they are difficult to reset.
    Click image for larger version. 

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  6. #16
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    Quote Originally Posted by Alfred M View Post
    Yes he needs to add a 63a mcb before the RCD as this unit does not have overload protection if he had installed a RCD with oveload protection then it can be used as a main switch at the moment there is no overload current protecting the 16mm incoming cable except for the council kiosk.
    I am not an expert on the regs but I don't see anywhere that says the main switch needs to provide overload protection. All I see is "6.6.1.1 Each distribution board shall be controlled by a switch-disconnector".

    The incoming cable is protected by the council board. And all the circuits in the DB are protected by individual circuit breakers (after the RCCB).

    My understanding is that the "distribution board switch-disconnector" or "main switch" is for isolation purposes so this function can be fulfilled with the RCCB device. Of course most modern circuit breakers can also be used as switch disconnectors ... but I do not see the requirement for a "distribution board - main overload device"

    Or am I maybe misunderstanding this particular installation?

  7. #17
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    Read 6.8.1 together with 6.7.5.7. I think that should make it more clearer

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    Each phase conductor of an installation shall have both overload and short circuit protection (6.7.1.1)

    Now check out (6.7.1.3 )
    These conductors may be protected by the suppliers overcurrent protective device, provided that
    A) the supplier agrees
    B)
    C) the user has access to the device.

    The supplier generally will not agree and these devices are usually in a locked kiosk, so the user does not have access to them.

    Here in our valley, the supply authority prefers a circuit breaker as mains in the main db so that should there be a major short or fault on the installation, it trips on the installation instead of outside in the kiosk or on the pole.

    Makes sense.

  9. #19
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    Quote Originally Posted by Leecatt View Post
    Read 6.8.1 together with 6.7.5.7. I think that should make it more clearer

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    Thanks Leecatt. As usual a long way around in the specs. Could really be simplified. If overload is required on main switch ... then just say it.

    But thanks I see your point ...

  10. #20
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    Quote Originally Posted by Derlyn View Post
    Each phase conductor of an installation shall have both overload and short circuit protection (6.7.1.1)

    Now check out (6.7.1.3 )
    These conductors may be protected by the suppliers overcurrent protective device, provided that
    A) the supplier agrees
    B)
    C) the user has access to the device.

    The supplier generally will not agree and these devices are usually in a locked kiosk, so the user does not have access to them.

    Here in our valley, the supply authority prefers a circuit breaker as mains in the main db so that should there be a major short or fault on the installation, it trips on the installation instead of outside in the kiosk or on the pole.

    Makes sense.
    Thanks Derlyn. What you say makes sense from a practical point off view.

    And I note what Leecat said ... but I have certainly seen some installations where the main switch is only an earth leakage switch without overload. Again makes me think the regs need rework

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