testing on TT system

[eagleeye]

I have just finished a rewire in wales. All the circuits tested out ok. but as i have never done a test on a tt system i was a bit confused on the reading for the earth loop impedance tests. The test on all circuits were coming in around the 15 ohm mark as did the Ze. is this correct or have i made a mistake. All main bonding conductors were disconnected with only the earth rod connected

 

[Des 56]

You are correct
A reading of 15 ohms for a TT system is an excellent result,considering up to 1667 ohms (30 m/amp)is ok
The wiring regs recomend a reading of under 200 ohms.so you are way within whats required

Remember the Zs figures in the big red book refer to TN systems

 

[Monkey1984]

As said that is a very good result. Round my way most of the results I get on TT systems are 150-175 Ohm range.

You have carried out the test correctly as well from what you have written, the only other way of testing a TT system is with an Earth Electrode Resistance Tester and that will take you a while because of having to install another 2 temp rods to test.

I always carry out the test the same way you have listed above