Zs - Calculated and Measured Differences

[chiplard]

Not too sure what to read into this!!

New installl in my garage and doing initial testing

Socket Circuit ( radial )

R1 + R2 = 0.03 ohms using link method in CU
R1 + R2 = 0.03 ohms measured Line and CPC individually ( done this just to double check )

R1 + R2 = 0.07 ohms - of SWA from CU in house to CU in garage

Measured value of Ze = 0.26 ohms - in high current mode

Zs = 0.26 + 0.03 + 0.07 = 0.36 ohms

Measured value of Zs = 0.56 ohms - in no trip mode

A discrepency of 0.2 ohm ( more than the 15% tolerance of the meter) ( Fluke 1651B)

I tried taking Ze again using no trip mode to see what that gave but could not get a reading.

Any ideas anyone??!!

 

[Des 56]

Best to take "no trip" readings with a pinch of salt.they are ok for general tests but tend to give inaccurate results for actual circuit readings
Go with your Ze + (R1+R2) calculations,they are to be relied on much more than No trip Zs tests

I can't understand what you meant by
The test you made individually R1+R2 line and cpc individually

 

[chiplard]

It was just a double check. The socket is right next to the CU so i tested the continuity of the individual cables. Just to verify the reading from the L-E link in the CU method.

 

[Crosswire]

Tried linking out the RCD then doing the Zs test on normal mode?
I know it's a pain , but might give interesting result.......