urgent help please

[james beckford]

I have just been called to a house. BG went in earlier to fit new meter and told homeowner that they had an earth fault and were live to earth.

Homeowner then called me, I carried out continuity test to circuit identified by BG as problem, results around .35 ohms - no problem there

Tested for power from the earth busbar - no voltage detected

Insulation test coming back at 40MOhms - not brilliant but very old property.

then carried out a voltage test at the sockets - bizarrely only getting 135V - getting 247 at the fuse board.

Any ideas as this one has me stumped.

Many thanks in advance gentleman/ladies

 

[telectrix]

what voltage L-E and L-N at CU? what earthing arrangement and what's the Ze? more info needed.

 

[Flanders]

Have you lost the main neutral and its grabbing the power from the earth

 

[Sharpend]

Suspect a loose or lost earth path? Therefore at point on circuit there is no reference to earth. Are you getting the 137 at all points on circuit?

 

[james beckford]

at the cu unit getting 247 V when i test across L-N and L-E, its a tncs by the look of it,

Havent tested Ze as didnt see the need

 

[Flanders]

best check ZE , check outgoing connection as CU and check ring continuity on the circuit. Is every thing unplugged from the circuit ?

 

[Sharpend]

What about the readings around the circuit?

 

[james beckford]

checked most of the plugs getting about 135V all the way round

 

[james beckford]

Correction looks like a TNS

- - - Updated - - -

Yes i had unplugged everything on the circuit

 

[Hants-Spark]

Have you tried all mentioned in post 6 yet? I would start there and see what you come back with. Good luck

 

[Flanders]

Is the voltage low on just the one circuit. If so just break that circuit down to find the fault

 

[telectrix]

what are you getting the 135V on, L-N or L-E? i assume it's L-E which suggests broken or loose connections on cpc/s. you need to measure r1,rN,r2, then R1+R2 to give some idea of the fault. check all earthing and bonding as well.

 

[Flanders]

what are you getting the 135V on, L-N or L-E? i assume it's L-E which suggests broken or loose connections on cpc/s.

I agree if its between L-E its a lost earth and grabbing power from fabric of building that why I ask to check ring continuity and connections at CU

 

[james beckford]

Thank you for all the advice, will go back to basics and start at the beginning.

 

[Flanders]

Let us know how you get on it bond to be something simple

 

[Hants-Spark]

Did you solve this???

 

[Engineer54]

I don't know how you electricians out there, get away with leaving the job without doing any meaningful fault finding!! I mean Jesus, this is a simple rectifiable fault were talking about here, about an hours work for an experienced electrician.