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Using BS3871 MCB to protect ne submain

Alan B

Is it ok to connect a new submain to an existing spare 3 phase BS3871 MCB in a light industrial installation. The alternative is to change the entire main DB.

Submain will be clipped direct to wall and steel roof beam. It will feed a new 3 phase DB, probably equipped with two 3 phase 16A MCB's.

My understanding is that BS 60898 replaced BS3871 and the standards are similar, I am sure there are some differences, but do they make a significant impact on safety? In my mind providing they disconnect in the required time everything should be acceptable? Main risks will be after the sub board using modern devices.

Thanks

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  • 0

    A personal opinion.


    The older I get the more risk averse I get, so with plug in MCBs  and fuses I generally turned the whole installation off, remove the fuse board cover, then disconnect the circuit and park the circuit conductors in the earth bar, put the fuse board cover back on and reenergise the rest of the installation.

    If the conductors won’t reach the earth bar use a fly lead and connector.

    It may seem over the top, but I have had idiots trying to turn circuits back on whilst I have been working on them.

Reply
  • 0

    A personal opinion.


    The older I get the more risk averse I get, so with plug in MCBs  and fuses I generally turned the whole installation off, remove the fuse board cover, then disconnect the circuit and park the circuit conductors in the earth bar, put the fuse board cover back on and reenergise the rest of the installation.

    If the conductors won’t reach the earth bar use a fly lead and connector.

    It may seem over the top, but I have had idiots trying to turn circuits back on whilst I have been working on them.

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