Spike and t-n-cs ?

[jules27]

Hello people ,looking for some help with this query, Have just started work (as a mate) for a water company . On their pumping stations (the green boxes you see) they appear to have a spike and a tncs system- is this allowed or normal for some installations? or have i missed something ? I ll get a picture and put it on next week so you can see for yourselves .It is to be part of our initial survey .

thanks

 

[malcolmsanford]

Originally TT, changed to TNC-S by DNO, nobody took the spike out, that happens a lot.

 

[jules27]

thanks for that info ,to do Ze should i disconnect spike ?

 

[malcolmsanford]

TNC-S should be max 0.35 ohms and the spike, well anyones guess but not highly unlikely to affect the TNC-S reading.

Disconect the earth conductor as normal and test the TNC-S Ze and see what you get. If you confirm that there is a TNC-S supply then disconnect the TT, confirm that you have that Ze before you disconnect anything.

 

[telectrix]

adviseable . to eliminate parallel paths and confirm that you have TNC-S. either way, you should get a reading of <0.35