New Build IR Testing RFC, can't find the issue

[JaegerZero1984]

I am currently testing a 2 bed flat, all other circuits read clear. Flat Ring not so much.

Using a Megger MFT1721

L - E Reading 300Mohms but slowly
L - N Reading 400 Mohms but slowly
N -E Reading 200Mohms but slowly

Have tried breaking the ring and narrowing down the problem but both sides come up with higher readings.

Have replaced half the ring and still no change.
Each leg reads +999
You pit a couple of sockets together it starts to drop. Tried replacing parts of ring with 2.5 to see if I can clear it but its not working.

Trying replacing a lag at a time tomorrow...

The plot is a new build so I would expect the readings to jump above 300 right away, so slow readings mean I'm having to investigate.

Does anyone here have any idea what could be causing these readings?

 

[Octopus]

Anything above 2 meg ohms is acceptable ......if the reading is rising slowly then I would suspect damp

Did you IR the sockets.

Did you wire the flat?

 

[davesparks]

If it is slowly creeping upwards it’s probably just dampness from the plaster drying out, loosen all the sockets a little bit and leave it for a few days if you are worried.

 

[LankyWill]

Thats just damp readings, i wait until i reach 300 M-ohms and then move on.

 

[Pete999]

I am currently testing a 2 bed flat, all other circuits read clear. Flat Ring not so much.

Using a Megger MFT1721

L - E Reading 300Mohms but slowly
L - N Reading 400 Mohms but slowly
N -E Reading 200Mohms but slowly

Have tried breaking the ring and narrowing down the problem but both sides come up with higher readings.

Have replaced half the ring and still no change.
Each leg reads +999
You pit a couple of sockets together it starts to drop. Tried replacing parts of ring with 2.5 to see if I can clear it but its not working.

Trying replacing a lag at a time tomorrow...

The plot is a new build so I would expect the readings to jump above 300 right away, so slow readings mean I'm having to investigate.

Does anyone here have any idea what could be causing these readings?

Damp

 

[Pete999]

I am currently testing a 2 bed flat, all other circuits read clear. Flat Ring not so much.

Using a Megger MFT1721

L - E Reading 300Mohms but slowly
L - N Reading 400 Mohms but slowly
N -E Reading 200Mohms but slowly

Have tried breaking the ring and narrowing down the problem but both sides come up with higher readings.

Have replaced half the ring and still no change.
Each leg reads +999
You pit a couple of sockets together it starts to drop. Tried replacing parts of ring with 2.5 to see if I can clear it but its not working.

Trying replacing a lag at a time tomorrow...

The plot is a new build so I would expect the readings to jump above 300 right away, so slow readings mean I'm having to investigate.

Does anyone here have any idea what could be causing these readings?

Not sure I understand "replaced part of Ring with 2.5??"

 

[The Ghost]

Any spurs badly wired in from the R.F.C.?

 

[JaegerZero1984]

Not sure I understand "replaced part of Ring with 2.5??"

Replaced part of the rings 2.5 cables to try to clear it.

 

[JaegerZero1984]

Any spurs badly wired in from the R.F.C.?

Re terminated the spurs and had to rewire a spur beccaus dry liners screwed the load cable.

 

[Pete999]

I am currently testing a 2 bed flat, all other circuits read clear. Flat Ring not so much.

Using a Megger MFT1721

L - E Reading 300Mohms but slowly
L - N Reading 400 Mohms but slowly
N -E Reading 200Mohms but slowly

Have tried breaking the ring and narrowing down the problem but both sides come up with higher readings.

Have replaced half the ring and still no change.
Each leg reads +999
You pit a couple of sockets together it starts to drop. Tried replacing parts of ring with 2.5 to see if I can clear it but its not working.

Trying replacing a lag at a time tomorrow...

The plot is a new build so I would expect the readings to jump above 300 right away, so slow readings mean I'm having to investigate.

Does anyone here have any idea what could be causing these readings?

So let me get this straight in my head, you have taken all the accessories off the RFC? IR tested each leg of the RFC? all >999Mohm, put the accessories back on, screwed them back and the IR readings slowly rise to around 300Mohm? if thats the case then a pound to a pinch of the brown stuff it's damp walls, a new build you said?

 

[JaegerZero1984]

So let me get this straight in my head, you have taken all the accessories off the RFC? IR tested each leg of the RFC? all >999Mohm, put the accessories back on, screwed them back and the IR readings slowly rise to around 300Mohm? if thats the case then a pound to a pinch of the brown stuff it's damp walls, a new build you said?

Yep. New build.

 

[The Ghost]

screwed the load cable

Sounds like that will help. No issue really as 300 Mohm meets regs?

 

[westward10]

You are looking for and trying to rectify a problem which does not exist.

 

[ipf]

I don't think I'd be worried about the odd 100,000,000 ohms, either.

 

[Risteard]

Why are we discussing 200,000,000+ Ohms readings?

 

[willy fixit]

My meter only goes to 200MegOhms! Should I get a new one! And the house I tested last week had IRs of 170M maybe I should condemn the installation!

 

[westward10]

I use an analogue meter, as long as I don't see the needle with my right eye all is fine.

 

[ipf]

I use an analogue meter, as long as I don't see the needle with my right eye all is fine.

......Always thought you were a bit of a winker.

 

[123]

Anything above 2 meg ohms is acceptable .....

Not too sure I'd be happy with that on a rewire or new install, damp from plaster or not.

 

[Deleted member 26818]

Change MFT.
Get one that only goes up to 299 Mohm.

 

[Baker1988]

I really wouldn't worry about it all all reading are perfectly acceptable just record the results and move on to next job, or go for a pint.

 

[static zap]

Not too sure I'd be happy with that on a rewire or new install, damp from plaster or not.

Surely this comes from the experience of un-doing all the sockets , letting them breath , getting a much better reading .. logic .
( if worried about tracking damage - I can see AFDs turning up sooner)
Is this "Damp from New Build plaster" effect common only in hot weather ?

 

[telectrix]

if it's a new build, it won't only be the plaster drying. the roof will leak. the plumbing willl leak, the plasterboard will be mouldy.

 

[telectrix]

any rate, my megger BM80 goes up to 100Gig on the 500V range, so ner,ner. .