- Reaction score
- 5,316
I am going to have to but in here and claim the all time record low for Ze on a TT system.
In Paris last week testing a new installation tested 0.14 ohms for a Ze on a TT (couldn't believe it).
The installation is a large office complex with a 3 phase TT supply. Main incomming cables are 240mm with 120mm main earth. This part of the installation was existing. After a lot of investigation as to the type of electrode used it was established that the 120mm main earth was conected to an earth plate buried in the courtyard of the building. From this plate a tape was run underground around the perimiter of the building and back to the earth plate in a ring.
Hope this gets me into the guinness book of records for lowest Ze on TT.
Out in Paris again last week to finish testing when i was made aware that there was also an earth tape connected from the earth plate to the district steam supply.
Apparantly these district steam pipes go underground for miles and supply heating to the entire city.
Now i can understand the low Ze.