Insulation resistance problem

[Schoe1]

Hi all i was wondering if anyone could shed some light on my problem. Came to test a ring circuit today L-L 1.23 ohms N-N 1.23 ohms E-E 1.98 R1+R2 0.73 then i did my insulation resistance tests L-N 500 ohms N-E 500 ohms then L-E 0.00. Nothing plugged in, only a few sockets connected the rest in junction boxes while the plastering is finished. Is there any obvious reason for this reading, how could i narrow down the problem? All the tests were carried out from the consumer unit.

Thanks very much

Chris

 

[Pete999]

Hi all i was wondering if anyone could shed some light on my problem. Came to test a ring circuit today L-L 1.23 ohms N-N 1.23 ohms E-E 1.98 R1+R2 0.73 then i did my insulation resistance tests L-N 500 ohms N-E 500 ohms then L-E 0.00. Nothing plugged in, only a few sockets connected the rest in junction boxes while the plastering is finished. Is there any obvious reason for this reading, how could i narrow down the problem? All the tests were carried out from the consumer unit.

Thanks very much

Chris

500 ohms then you have a problem, any Neons, loads connected, or are you reading your MFT wrong? were you testing IR on the IR setting?

 

[bigspark17]

Is this a new install or an eicr on an existing installation?

 

[Leesparkykent]

megohms or ohms? you have a short L-E....screwed/nailed through cable etc.

 

[ruston]

Plasterers water in your jb's or the back boxes, sockets wet,fly leads pulling your reading of Mohms down

 

[Schoe1]

Sorry 500> Mega ohms

 

[davesparks]

At a guess I would say that there are two different faults, the one causing the 500ohm readings and the direct short.
I say two faults as having a precise 500ohm reading twice is so extremely unlikely that it's almost certainly the same fault causing both.

Just follow the usual fault finding procedure of logical division of the circuit to find these faults.

It would be interesting to know what has caused the 500ohm fault though as it's such a precise round number and faults generally don't conform to such things.


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[Schoe1]

it is a new installation

 

[Schoe1]

no loads connected, no neons,not reading the MFT wrong, and testing at 500 volts

 

[Pete999]

Sorry 500> Mega ohms

You meam MEG OHMS

 

[Schoe1]

I didn't have long to investigate today, quickly split the ring and tested as two radials got o.oo reading again on both L-E

 

[Pete999]

I didn't have long to investigate today, quickly split the ring and tested as two radials got o.oo reading again on both L-E

What scale were you testing at Res or IR?

 

[Schoe1]

Sorry miss type yes Meg ohms

 

[Schoe1]

What scale were you testing at Res or IR?

Sorry Pete not sure what you mean, I was testing the Insulation resistance at 500 volts.

 

[Pete999]

Sorry Pete not sure what you mean, I was testing the Insulation resistance at 500 volts.

Don't know if it's me but your description of the readings you are posting are misleading, to help us/me help you, you need to be more explicit when describing your readings "I tested as 2 radials and got 0.00" don't mean a lot you have to admit, sorry if I come across as a git, but I don't mean to honest.

 

[telectrix]

sorry if I come across as a git, but I don't mean to honest.

C'MON PETE, WHY BREAK THE HABIT OF A LIFETIME?

 

[davesparks]

I didn't have long to investigate today, quickly split the ring and tested as two radials got o.oo reading again on both L-E

The go back and test it when you do have time.

 

[Schoe1]

Don't know if it's me but your description of the readings you are posting are misleading, to help us/me help you, you need to be more explicit when describing your readings "I tested as 2 radials and got 0.00" don't mean a lot you have to admit, sorry if I come across as a git, but I don't mean to honest.

Sorry not a problem my fault. So the insulation resistance readings test at 500v

L-N = 500>megohms (reading fine)
N-E = 500> megohms (reading fine)
L-E = 0.00> megohms

Quickly split the ring circuit and tested as two radial circuits and on both radial legs I got the reading again of 0.00> megohms which i wasnt expecting. If there was a break in the cable i should be getting a reading on one radial circuit.

 

[bigspark17]

Is this a new install.???

 

[Schoe1]

Yes its a new install.