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Higher permitted zs on a rcbo protected circuit

Highspark

Hi all am looking for thoughts on a zs slightly higher than max permitted zs 

I was testing a large holiday let  with a 100 amp three phase supply  and a 3 phase distribution board with all rcbo c type  installation was tidy bar a few items needed  addresses and the socket circuits are poorly design 2.5 ring final circuit on c type rcbo and are wee bit over the max zs  just looking for thoughts and regulation on how to code this I would recommend change for b type  but there are 7 crabtree rcbo what are around  £30+ each and just looking for justification for them for client 

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    And volt-drop is met.

    Absolutely - my comment was only meant to be taken in the context of the value of Zs itself. I didn't mean it imply that there was nothing else to consider - be it voltage drop, protection of the conductors from faults, possibility of poor joints or a break in the ring that might lead to an increased impedances, thermal insulation around the cables or many other things.

       - Andy.

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  • 0

    And volt-drop is met.

    Absolutely - my comment was only meant to be taken in the context of the value of Zs itself. I didn't mean it imply that there was nothing else to consider - be it voltage drop, protection of the conductors from faults, possibility of poor joints or a break in the ring that might lead to an increased impedances, thermal insulation around the cables or many other things.

       - Andy.

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