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Hacker

High zs reading on a new build beco house

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Hacker

Just finished another beco house but a little bigger with vaulted ceilings this one . Cable runs were long but installed more circuits, my socket ring got 0.84 . Was wondering if because the cables are inside an insulated wall would have an effect? And anything that could be done to improve the results? . My next project will be bigger and would like to see more usual readings, anything to be advised on??

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Doc Hudson

High -vs- Usual?  how are you defining these values?  Something is only high if it is out of proportion to the cable lengths involved. e.g. I bought a round of drinks that cost me £25 do you think that is high?  Maybe yes if there was only you and three friends,  but not if it was a group of twelve old school mates?  As you include no specifications of lengths, CSA of conductors etc.. not much anyone can say really. 'Usual' is only 'usual' if it is proportional to the cables lengths, and the tables in BS7671 can give guidance as to expected values for different lengths at various conductor CSA. You can't just expect every job to have the same values.

 

Doc H.

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kerching

Surely if this is a large property then the issue of long cable runs would have been flagged up and addressed at the design stage?

resulting in, amongst other things, installation of one or more sub mains feeding local boards, larger cable sizes etc

 

socket ring got 0.84....what does the design project the results to be

is this R1 + R2, r1+r2, etc etc etc

what is Ze

 

also 'cables in Insulated wall'......for what length?, thickness of insulation?     How much have they been de rated?  ( 4mm in 0.5m of insulation > 100mm is ( off the top of my head) only good for 16A

 

as for the insulation effecting the resistance, well.........

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Andy™

is your Zs off fom your cable design calculations? what about R1R2? higher than expected or not?

Edited by Andy™

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Murdoch

What were the end to end readings? What is the Ze?

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Bruspark

Do the readings differ from your design calculations ?  

.... Or is this a silly question 

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Adrian

My worry would be the installation method 

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