Tncs or TT ?

[jonthesparks]

Does the DNO change TT systems into tncs by changing the head to a tncs cut out and providing met? The Ze I measured was 0.60 and when main earth reconnected reding of 0.40 on the met . There is an earth electrode and 30 mA rcd as a main switch . Is this a TT system or tncs ?

 

[Rob Smith 643]

Job today had TT in place and connected through to CU. Service head/cut out has PME sticker but no earthing conductor through to CU. Householder advises that they had a meter change approx five tears ago. Since that time they've had PV fitted and a CU change. No cert for CU change but householder advises it was the same guy who did the PV hook up. There is a cert for that, recorded as tncs... Fun city.

 

[Kate]

Haha.although the few PV installs ive seen I havent thought much to the hook up at the board/meter.

My job today had TT. full test following DB changes. Had 5 hours of, on average, 2.8ohms Ze to the circuits. Then it jumped to readings of 28.3ohms. Any ideas other than tester batteries might be dying?

 

[telectrix]

or eyes misplacing the decimal point!. happens to me after beer.

 

[Solarandelectri]

adam ha

 

[Kate]

Lol I eat my carrots my eyes are good got my helper to double check. Even retested the previous circuit and that had changed.

 

[Richard Burns]

I would think the tester, failing batteries, loose test cable (or probe).
If not that then a loose connection at the main switch / tails that has just shifted a bit.

 

[Kate]

Thanks just glad its nothing monumental. Already knew batteries were getting lowish, enough to tell myself to remember i need new batteries so its likely that

Checked board connections