Possibly loss of the earth to the neutral point of the Tx?


Regards


BOD

a partial loss of neutral next door  coupled with poor or non existant earth rod?

If the 210 volts neutral to earth is measured at the installation between the supply neutral and the local electrode it suggests that something has lifted the supply neutral above earth potential.  The transformer earth electrode could have a resistance to the general mass of earth of as much as 20 ohms.  A 10A earth fault current flowing back to the transformer via this electrode could raise the potential of the neutral wrt true earth.  This fault current could be coming from a different installation(s) connected to the same transformer.


Regards


Geoff Blackwell

Are we allowed to know why the electrician had been called in - had things stopped working, had the householder experienced a shock? Did any of the other villagers have a problem?


L-N is normal. L and N appear to have floated up more or less together, so as BOD suggests, perhaps the transformer is no longer grounded?


Could there be a problem on the HV side? (Just guessing now!)

I'd go for a simple but uncleared L-PE fault in a neighbouring property that happened to be on a different phase. Either no or faulty RCD and the faulty installation happened to have a significantly better connection to true earth than the Tx.

  - Andy.

My guess.

shared but isolated water service.

Neighbours faulty or non existant rcd. Neighbour on second phase with fault to earth.

Yes a fault on another phase to Earth is possible along with an open or high resistance TX Earth connection. To get the measured results 210V to Earth needs 11A or so across 20 Ohms, or a lot more current if it is lower. The only point about that is that pole pigs are usually single phase. Bigger transformers have 2 poles, but perhaps Alan was a little "quiet" to make the problem more difficult! I am a bit confused because a few customers would only get a single phase. But otherwise, I reckon I may be correct.

I know of at least one 3-phase transformer up a single pole. Rated at 50 kVA.

I know of at least one 3-phase transformer up a single pole. Rated at 50 kVA.


I believe WPD will go up to 100 kVA on a "stout" pole Chris, not the GPO sized ones or age though!


315 kVA on a H pole. Just thought it should be plural for two but always spoken of an H pole. There we go again, a or an before H here?


Regards


BOD

The only point about that is that pole pigs are usually single phase.

I wonder if there's a bit of regional variation - around here 3-phase pole mounted transformers are probably as common as single phase ones.

   - Andy.