Another Strange Fault

[bernardgreen]

One more thought.

If the dimmer was operating into a transformer ( wound type ) the non sinusiodal waveform from the dimmer might be reacting in the coild of the transformer to produce high voltage low energy spikes. ( as per car ignition coil ).

Your meter may be showing the voltage of the spike.

Make up a load of two 230 bulbs connected in series and put this across where you find 400 volts. If they light you have a second phase involved or the incoming neutral is extremely suspect.

Stick a earth rod in wet ground and use that as a reference to measure the voltage on the incoming neutral. More than about 50 volts between neutral and the earth rod means the network hasa problem with their neutral.

 

[securespark]

Been back today.

Tested voltages again, this time with Alphatek.

N/E = 210V.

L/E = 249V.

N/L = 5V.


Sure there is an open neutral somewhere, but some of the lighting feeds disappear under tiled floors (!) and TBH, I can't find any lights that don't work, so where do those feeds terminate?

Found a good live/neutral feed on the same circuit, re-fed the dicky lights & they work now. But cannot trace cause of tripping breakers & have no plausible explanation of why two independent breakers are tripping together... Your suggestions so far have not proved to be.

 

[bernardgreen]

Strange in deed

400 volts ( or has it gone ).

How large is this property ? Could it have once been two small properties combined to make one large house. And some where there is remnants of the redundant mains incomer still live.

( I once found a 240 to 12 volt world war two power unit bricked up in the wall of a cottage, still live and fed from another location by private underground cable )

The two trips going out together. If a MCB is close to its tripping current a tap or other vibration can take it out. Vibration along the DIN rail from the lighting MCB tripping with the BIG noise have tripped the other one that was close to its tripping point.

Is there underfloor heating under the tiles where the lighting cables dis-appear. Is it possible there is a complex short under the tiles involving heating ( the other MCB ) and lighting cables.

just rewire the whole place....

 

[sparkyspike]

Do you have ****** living next door?

 

[securespark]

400V still showing on voltage probes, but Alphatek says 249.

I belive the A/tek...

It is (and always has been) a large detached property, with 1P supply.

Although one of the breakers would be close to its limit if everything was switched on together, the popping occurs ATT, regardless of load.

Suspect open neutral, as I said earlier, and possible rodent damage. Breaker behaviour is similar to another property with squirrel damage to lighting cables in loft. But all the cables I have been able to access have been OK. Must be something, though, but what??

Cables go in the void under the tiled floor, not directly under the tiles.

Point being I cannot access the other end of the cable...

 

[sparkyspike]

I think I would be IR testing the installation by now!

 

[securespark]

But all the cables I have been able to access have been OK.

 

[sparkyspike]

Sorry, didn't realise you'd already IR tested. Did you test the whole load side of the board?