Cant get a Zs reading ? ? ?

[Joe S]

Hi, I cant get a Zs reading from the majority of my new circuits. I do get a reading between the incomers to the d.b and the main earthing conductor and I can get the RCD tripping. The system is TT and its a total rewire. Any help would be appreciated.

 

[Joe S]

Hi, I cant get a Zs reading from the majority of my new circuits. I do get a reading between the incomers to the d.b and the main earthing conductor and I can get the RCD tripping. The system is TT and its a total rewire. Any help would be appreciated.

 

[G_FUNK]

tt has a high earth return path ze so a high zs would be normal, hench why rcds are fitted. you have a ze reading right? and you have a r1 + r2 for every final circuit? the rcd will trip as long as it has power. but have you rcd tested any of your final circuits?
i did a large shed that was being turned in to a office and im sure my zs reading on all the final ciruits were around 27 ohms. the earth spike was buried in the grass and was one metre deep it had rained alot so the ground was moist.

Where is your earth spike and how deep is it? you may need to make it deeper or drop a second in paraell to the first spike.

 

[Joe S]

tt has a high earth return path ze so a high zs would be normal, hench why rcds are fitted. you have a ze reading right? and you have a r1 + r2 for every final circuit? the rcd will trip as long as it has power. but have you rcd tested any of your final circuits?
i did a large shed that was being turned in to a office and im sure my zs reading on all the final ciruits were around 27 ohms. the earth spike was buried in the grass and was one metre deep it had rained alot so the ground was moist.

Where is your earth spike and how deep is it? you may need to make it deeper or drop a second in paraell to the first spike.

I cant even get a Zs mate. I have my meter set to 'ZS RCD' so as not to trip while testing and it comes back with no result. Normally I press TEST 2 or 3 more times as when the battery starts to get low it gets slow. the spike is about 200mm out of the ground due to shingle and paving.

All circuits trip the RCD within the proper times on both x1 and x5.

Would another spike linked to my first give me a Zs reading?

 

[Spudnik]

You have the range set too high on your tester.

 

[Joe S]

You have the range set too high on your tester.

What range should it be set to mate? I have a Metrel 17th Ed. all in one tester.

 

[scotsparky]

hi mate does your tester have a no trip funtion (d-lock) whe a third lead has to be used to prevent rcd tripping?

 

[cornburn]

Have you zero'd your test leads properly? If not the resistance of these will likely be higher than your loop reading, giving you a result of 0 (as it won't show a minus figure). At least this is how my Fluke works and it caught me out the first time I used it.

 

[Joe S]

hi mate does your tester have a no trip funtion (d-lock) whe a third lead has to be used to prevent rcd tripping?

It does mate, the 'ZS RCD' lights up in the top left corner. Takes longer to give reading aswell.

Have you zero'd your test leads properly? If not the resistance of these will likely be higher than your loop reading, giving you a result of 0 (as it won't show a minus figure). At least this is how my Fluke works and it caught me out the first time I used it.

I'm sure I've nulled them to 0 which should have been stored in the memory. Could check it again though

 

[scotsparky]

Take a reading using the d-lock ZS rcd function i know it takes longet but be patient. You should be able to get a readding with that. if not prove your R1 and R2 using method 2 the long lead method and to double check your connections.

 

[G_FUNK]

check that you main earth is still connetcted to your spike first off. your rcd will still trip so long as its a bsen 61009 as the dont have a functional earth.

your could just try connetcing a second spike to the 1 st and drive it in the ground so you have 2 metres of depth or connet a 2nd in parallel. when doing this all your trying to do is put up a effective earth. You wont ever get an earth as good as a tncs on tns on a tt. you will be protected against fault protection via your rcd tho. but you should try and get that zs reading.

what type of soil is it that the spike is in? rocky soil or not?

 

[Joe S]

check that you main earth is still connetcted to your spike first off. your rcd will still trip so long as its a bsen 61009 as the dont have a functional earth.

your could just try connetcing a second spike to the 1 st and drive it in the ground so you have 2 metres of depth or connet a 2nd in parallel. when doing this all your trying to do is put up a effective earth. You wont ever get an earth as good as a tncs on tns on a tt. you will be protected against fault protection via your rcd tho. but you should try and get that zs reading.

what type of soil is it that the spike is in? rocky soil or not?

I will have to try that 2nd spike idea. I'm a little worried I cant get a Zs. The ground as far as I know is mud. My spike sits up 200mm due to the surrounding paving and french drain around the house.

 

[calv68]

what was ze reading when you bashed the spike in

 

[Joe S]

what was ze reading when you bashed the spike in

From memory I think it was 147 ohms but cant be sure.

 

[snowiespark]

sure the tester is working corect? our fluke says it cant get a Zs sometimes, and it was the neutril connection on the test lead plug causing it...