Head Scratcher Time.

[telectrix]

this is baffling.
situation is an existing rfc that has had a minor repair. a socket had been removed and the live cables left in back box and tiled over. cables were pulled back above ceiling and jointed.

prior to reconnectio in a new CU tests were done on the circuit.

now here's the baffling bit:

r1 = 0.28
rN =0.28
r2 = 0.47

fine so far, expected R1+R2 = (0.28 + 0.47) /4 = 0.1875

measured R1+R2 = 0.17 . perfeck.

then, here's the rub....

Rn + R2 = open circuit, tested at 2 points on the ring.

both R1 + R2 and Rn + R2 measured with the respective ends cross connected @ CU.

it's as if the N's are continuous but loose in the sockets but sockets were working fine before.

tester plug lead checked as OK by plugging in a socket on another circuit and live readings were normal.

as i said, a head scratcher.

 

[andyb]

What tester are you using Tel?

 

[telectrix]

i been out of my depth for ages , swimming against the tide of 'er indoors, her ma and her daughter. all seem to think i have a magic wand. fix anything from a leaking roof to a broken karzi. all the while while jabbering over what happened in last night's episode of emmeroids or which starstruck wannabee screecher will win the pox factor.

 

[telectrix]

What tester are you using Tel?

was with a fluke mft. Simon's, not my megger.

 

[andyb]

was with a fluke mft. Simon's, not my megger.

Feel free to hurl abuse my way if you think my next question is demeaning Tel, but.

Did you swap the neutral plug at the tester with the earth plug before testing?

 

[telectrix]

Feel free to hurl abuse my way if you think my next question is demeaning Tel, but.

Did you swap the neutral plug at the tester with the earth plug before testing?

no. tester with plug lead still attached was plugged into a socket on another circuit. L-N 240V. L-e 240V. N-E 0v.

 

[andyb]

no. tester with plug lead still attached was plugged into a socket on another circuit. L-N 240V. L-e 240V. N-E 0v.

What I meant was, on continuity the tester will only read between live and earth, as far as I'm aware. You have to swap the live and neutral plugs on the tester.

 

[telectrix]

What I meant was, on continuity the tester will only read between live and earth, as far as I'm aware. You have to swap the live and neutral plugs on the tester.

think you may have cracked it there. if i had been using my megger, it might have been different, but was using Simon's Fluke MFT. not used to the Flukes.

 

[Toneyz]

Tel, I take it you got R1 + R2 of 0.17 at all of the outlets which would count out a interconnected ring. Post 22 has posted ahead of me so it could be that. if not take the socket off and see what you get on the terminals.

 

[telectrix]

Tel, I take it you got R1 + R2 of 0.17 at all of the outlets which would count out a interconnected ring. Post 22 has posted ahead of me so it could be that. if not take the socket off and see what you get on the terminals.

andyb has got it in one. post#21. we had shorted N-E but the MFT was trying to read R1+R2. and so could not see the shorted pair.
thanks andyb.