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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 in reply to Sparkingchip
    Sparkingchip said:
    Electrical Safety First Best Practice Guide Two says BS3871 MCBs are unlikely to be suitable for isolation without explaining why 

    I have explained this above - including not being marked.

    However, arguably the same consideration should be made for older isolators, which also pre-dated the agreed marking, and also don't meet current standards for isolation.

    My concern here is that It seems we are injudiciously applying "rules and exceptions" in some cases and ignoring others ... which can't be right?

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