puzzling readings

[mikel]

Can anyone shed some ligh on why I got the following readings? This all started with a phonecall from a plumber who had got an electric shock from a washing machine he had to pull out. The house owner got a appliance repair man to check the washer which he said was ok. I checked the incoming supply and found that it was a TNS system with a wylex fuse board containing 3036 fuses. The gas and water were bonded, the continuity of the bonding was ok. The house had new gas central heating fitted. I checked the voltage between the copper piping of the heating system and it was 0. I then checked between the earth terminal of a nearby socket and the copper pipe of the heating system and got 63v. This occured on every socket to the pipework. I then checked the sockets and got the following readings

P-E 136V, P-N 247v, N-E 136V.

I checked the R1,R2 Rn and they were ok. Insulation tests were also ok. Only the sockets were affected. I then 'reassembled' the circuit and retested everything only to find everything now tested ok. Started to plug household appliances in and still got good readings the fault seems to have gone. Any ideas what could have caused these readings, only thing I could find was the cpc in the consumer unit was not tightened. I'm stumped

 

[Andy™]

loose earth connection in CU is just about the only thing it could be. had a similar problem a few month ago, but on everything. TT supply with no bonding to gas, and no rod. 10mm

 

[green-hornet]

I would agree by doing the testing and re establishing a true connection you have solved the mystery.

 

[sarni31]

Can anyone shed some ligh on why I got the following readings? This all started with a phonecall from a plumber who had got an electric shock from a washing machine he had to pull out. The house owner got a appliance repair man to check the washer which he said was ok. I checked the incoming supply and found that it was a TNS system with a wylex fuse board containing 3036 fuses. The gas and water were bonded, the continuity of the bonding was ok. The house had new gas central heating fitted. I checked the voltage between the copper piping of the heating system and it was 0. I then checked between the earth terminal of a nearby socket and the copper pipe of the heating system and got 63v. This occured on every socket to the pipework. I then checked the sockets and got the following readingsP-E 136V, P-N 247v, N-E 136V.

I checked the R1,R2 Rn and they were ok. Insulation tests were also ok. Only the sockets were affected. I then 'reassembled' the circuit and retested everything only to find everything now tested ok. Started to plug household appliances in and still got good readings the fault seems to have gone. Any ideas what could have caused these readings, only thing I could find was the cpc in the consumer unit was not tightened. I'm stumped

Not sure Why your live testing at this point??

surely continuity of protective conductors...

continuity of ring finals

would be first

Ze is always a good thing to check ..

Guiness Drink

 

[sparkyrj]

I had a similar problem with a washing machine a few years ago, and it turned out to be the cpc was loose in a 13A spur that supplied the socket that it was plugged into.

 

[Evans Electric]

I can only think that the washing machine has some leakage to earth , you say the sockets earth connection at the board was loose , so fitter gets a shock, fault voltage is now being carried away the earth cable.

The dodgy readings must have been due to induction in the un-connected earth wire, in fact, on second thoughts , that induced voltage may be what the fitter felt at the machine.

Deke

 

[Andy™]

Not sure Why your live testing at this point??

depending on fault, its often easier to fault find live