what is best tn-s or tn cs

[RF Lighting]

Those are the maxima for installations to which the OSG is applicable, because they are assumed in the tables for circuit lengths etc.

But where are they defined as the maximum permitted values? They are what they are, and will affect the maximum R1+R2 values permitted so that the maximum permitted Zs values are not exceeded, but unless there is a definitive requirement in the ESQCR which forbids suppliers from allowing their Ze to exceed those limits then they aren't maximum permitted values...

If I come across a supply with a Ze exceeding those values, my DNO (YEDL) will attend for free, and will maintain or replace their earth terminal, and leave a supply with a Ze less than or equal to the applicable value

 

[ban-all-sheds]

Good show....

 

[securespark]

Ban, I have to agree with RF: these values are accepted by the industry as maxima.

The ONLY exception I have ever come across (buit it has been VERY rare) is some TT > PME conversions, where very occasionally the 0.35 max. cannot be adhered to.

For more information, ring the Energy Networks Association on

020 7706 5100.

 

[ban-all-sheds]

Ban, I have to agree with RF: these values are accepted by the industry as maxima.

I know they are, but that does not make them the maximum permitted values.

Permitted by whom?

Permitted under what law or regulation?