Zs value and loose connection

[bobsmate]

If you have a zs value that is within the allowed regulation is it still possible to have a loose connection?

Sorry about some starting so many threads. I just worry loads.

 

[Spark123]

Yes it is
What sort of cable and how long is it? What is the R1+R2?

 

[bobsmate]

Its a 10mm2 cable for a shower and i took one reading and it said 1.79 then another and it gave me 0.64.

 

[RF Lighting]

Does your tester have a valid calibration certificate and a recent set of batteries?

 

[Spark123]

How long? 1.79 ohms as an R1+R2 value is a fairly long length of 10mm, as is 0.64 ohms.

 

[bobsmate]

Only about 20 m long and yeah it was calibrated about 2 months ago, would old batteries be giving readings like that?

 

[RMS]

Have you test the external impedance of the installation?

Maybe try your tester on a socket a few times and see if your readings are consistent.

 

[BS3036]

I don't think you should have started this second thread. Continuing the old one where these questions were answered already would have been so much better.

 

[fattony]

my fluke gave random readings which turned out to be old batteries, the battey low light wasnt even on!

 

[RF Lighting]

Yep, old batteries can give funny readings even if the battery indicator is showing them as being ok.

 

[bobsmate]

Seemed to have sorted it now when i got back to the job i decided to run another zs test on the shower only this time it gave me 3.??, so then i went round and checked every connection which were also tight. Then after a bit of head scratching i decided to change the rcbo for an mcb and got i reading of 0.36 (i also had a r1-r2 reading of 0.12 and ze of 0.24) i did this test again and also got 0.36. I then put the original rcbo in again and failed to get a reading at all before it tripped out, so in the end i left it on a 32a 30mA rcbo for the weekend which was giving me a bit higher readings but i was doing it on the trip test on my tester so therefore was expecting it.

 

[Spark123]

R1+R2 of 0.12 ohms isn't bad.
I take it you were using D-Lock or a low current type measuring device? These generally do give a higher than normal reading, especially if there is any noise on the system.