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earth conductor size


eleck

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Can anyone tell me the minimum meter tail and earth conductor sizes for a tncs pme installation with either a 60 or 80 amp bs1361 main fuse.have been told most people would fit 25mm meter tails and 16mm earthing conductor to err on the side of caution. Currently have a 10mm earth conductor for the above installation is this acceptable.

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Can anyone tell me the minimum meter tail and earth conductor sizes for a tncs pme installation with either a 60 or 80 amp bs1361 main fuse.have been told most people would fit 25mm meter tails and 16mm earthing conductor to err on the side of caution. Currently have a 10mm earth conductor for the above installation is this acceptable.

i would use 25mm meter tails and upgrade earth to 16mm. sure this is wat the brb says anyway.

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Can anyone tell me the minimum meter tail and earth conductor sizes for a tncs pme installation with either a 60 or 80 amp bs1361 main fuse.have been told most people would fit 25mm meter tails and 16mm earthing conductor to err on the side of caution. Currently have a 10mm earth conductor for the above installation is this acceptable.

16mm For the earth...

As for a 60/80A hed, 16mm tails would be OK, but 25mm is considered the norm..

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Its the Main Earth not bonding they are talking about.

It's a PME supply. The same rules apply to Main earth conductors as apply to the Main equipotential bonding conductors.

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It's a PME supply. The same rules apply to Main earth conductors as apply to the Main equipotential bonding conductors.

Actually I have always read that as 16 < CSA => 35 == 16mm (for 25mm tails) and that if 16 or less then its CSA but only down to 10mm. So if CSA of tails is 6mm then earth still needs to be 10mm.

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I don't understand quite what it is you have written here. I think you are mixing up the tables.

With PME installations, the minimum Main earth conductor and Main equipotential bonding conductor CSA required to comply with BS7671 is 10mm

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I`m not going to weigh in on this tonight, as my reference materials are out in me van, and I`m inside, nice and cosy with me Guinness.

I`ll pile in tomorrow :) ( go easy on me, I`m only little!)

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I thought that for tails up to 35mm that the main earth had to no less than half the csa of the tails and that you also had to abide by the DNOs rules for the size..

I could be wrong though!

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it based on the nutral

25mm tails 16mm earthing conductor 10mm main protective bonding conductor

if u have 16mm tails then its still 16mm earthing conductor and still 10mm for the main protective bonding

as for the fuse amp if it was 100A then deff 25mm tails

not sure for anything lower but if its being changed them put 25mm in to isolator and let the provider do the rest

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I don't understand quite what it is you have written here. I think you are mixing up the tables.

With PME installations, the minimum Main earth conductor and Main equipotential bonding conductor CSA required to comply with BS7671 is 10mm

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thanks for the replies, currently have 16mm meter tails and 10mm earth conductor. the consensus seems to be that the meter tails are ok but still unsure about the earth conductor size, i originally would have agreed with spinlondon but now i'm not so sure, unless i get some sort of agreement from you guys i will probably contact the dno for a definitive answer.

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Wouldn`t expect you`ll get a "definitive" answer from the DNO. Fit 16mm - why not. It sure as heck isn`t going to fail the regs anytime soon, is it????

KME

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Read 542.3.1. It states that main earth has to comply with 543 (i.e. table 54.7) AND meet the requirements of 544.1.1 (i.e. the info you posted above).

Yes you are quite correct, if PME the Main earth must comply with both section 543 and 544.1.1.

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I have just installed two earth rods on a school rewire, nice location, in the woods, fairies found at the bottom of the garden type of install.

I have done all main and supplementary bonding in 16mm, I suppose I need not have but my Za, Ze,and Zs readings are to be proud of.

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