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80 Amps Fuse with 25mm2 Tails with 10mm2 Earth

amlec2021

I came across an installation with an 80 Amp fuse with 25mm2 Tails and 10mm2 Earth and ondered if there was a requirement to upgrade the 10mm2 Earth to 16mm2.

The 10mm2 Earth comes straight from the MET in the DNO cut-out and therefore I am unable to access this to remove the 10mm2 and replace with 16mm2.

Can anyone suggest a way to verify if the existing 10mm2 Earth is acceptable.

Many thanks

  • +1

    It does not comply with 543.1.4, but it may comply with 543.1.3. What you need is the let through energy of the fuse and a pencil and paper to do the simple maths.

  • +1

    from the OSG (at least the old version I've got) - 5s disconnection time for a 80A BS 1361 fuse and a 10mm² c.p.c. is good provided Zs is ≤ 0.40Ω

      - Andy.

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