Help with test results.

[electek]

Hi , Just aquired a 2nd hand tester (Robin kts 1620) and decided to do a few tests around my house , now i know this system is TT and has a 100mA rcd unit fitted before the CU , The CU has just a main switch ( no rcd ) and circuit breakers.

Here are test results carried out on RFC (There are appliances plugged in on this circuit)

earth loop impedance

20 ohm range - overload , 200 ohm range - 25.4 ohms , 2000 ohm range - 31 ohms

Here are the test results carried out on a ceiling rose in a bedroom

earth loop impedance

20 ohm range - 0.04 ohm , 200 ohm range - 3.2 ohms , 2000 ohm range - overload.

Can anyone help me with these test results

 

[m4tty]

When was it last calibrated ??

 

[electek]

Hi , not sure as just aquired it !

 

[Des 56]

This is just speculating a bit.i dont know the meter
This may be possible with a two lead tester

The ring circuit has a sound insulation value, between neutral and earth,so the readings reflect the TT expected
The lighting has a low neutral earth insulation value (not enough to imbalance the 100m/amp rcd but enough to affect the results) what you are reading may be more an earth loop reading down the neutral of the supply

 

[electek]

Hi , just done an earth rod resistance test and found it to be open circuit ! suspect the earthing to be through the earth clamp on the water piping ! I know this isn't right and looks like i need a new earth electrode. However the earth resisitance through the water pipe was between 25 ohms and 80 ohms depending on which setting i use on the tester - why does the tester give such differences in resisitance on the different ranges i.e 20 ohm , 200 ohm and 2000 ohm ?

What is the maximum Ze (through the earth rod) on a tt system ?

 

[Guest123]

Ideally be 200ohms or less according to ol' red.

 

[electek]

Thanks , but why the differences depending on the earth loop setting on the tester ?