Measuring Ze and Zs

6 Feb 2006
Reaction score
United Kingdom
Hi peeps....
Just been reading about these tests and was wondering.....
When measuring Ze we would carry this test out with the earth conductor temporarily disconnected from the MET, which will also count out any parallel earth paths and a false Ze reading.
Add the Ze to our R1+R2`s of each circuit and we get our Zs`s.


When carrying out a straight Zs test on an energized installation,all main equipotential bonding will be in place and the reading we get will include these parallel paths.

Is there any way to eliminate these parallel paths?
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This is one of the reasons why measured and calculated results are always different... and if there not slightly different its a good indication that someones cheating on the test cert.
The theory behind this is you dont want to disconnect ANY bonding when the supply is energised for obvious reasons. But you know this already. I Have no idea how to eliminate parallel paths safely when measuring Zs. I suppose if you apply rule of thumb from the tables this will take into account (correction factors) but will this take into account parallel paths???? Anyone

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