Strange Insulation Resistance results

[Barx]

Here is what I currently see as a strange situation. Though I am hoping that with the responses of a few brain boxes, it will be cleared up.

Was doing some testing today and went to IR test a circuit (Upstairs Sockets). I had disconnected everything and even checked that there wasn't a booster, etc in the loft. Still airing on the side of caution I did a 50v (L-N) to cpc. Got 35.6 Meg Ohm.

Instant thought 'ooer, this aint right'. did it on 100v and got 66.3 meg Ohm. tried 250v and got >200.........

No, by reconning, those results sound the wrong way round. Surely the more pressure you put behind a insulation breakdown, the more it will give. I would expect a lower reading with higher voltage.

Obviously being dumb and missing something.

Please enlighten

 

[Blue Duck]

RCD socket?

I'm not a brain box though...

 

[Barx]

RCD socket?

I'm not a brain box though...

nope

thanks for trying though

 

[Lurch]

Did you retry it at the lower voltages again after it cleared?

 

[Barx]

Did you retry it at the lower voltages again after it cleared?

Yup, 3 times, same each time give or take a .1 or 2

 

[Murdoch]

Damp in system, progressive tests "heated" and dried the moisture and hence the improved results...

 

[rapparee]

Did you retry it at the lower voltages again after it cleared?

Yes, there could have been moisture, and you "fried" it off

 

[Andy™]

and it suddenly returned when he tried again on lower voltage?

 

[Lurch]

and it suddenly returned when he tried again on lower voltage?

They all replied at the same time.

 

[rapparee]

They all replied at the same time.

Yeah lurch was the last man visible when I replied.

 

[Bruspark]

Neon indicator somewhere ?  Still shouldn't pass less current as voltage increases but they can be a bit random . . 

 

[Barx]

Neon indicator somewhere ?  Still shouldn't pass less current as voltage increases but they can be a bit random . . 

I checked everywhere, there was nothing to be found.

Even if we say there was something connected somewhere I cannot think of anything that would give results like this.

Interesting one isn't it...

Wish I had videod it now as people probably think i'm talking a load of rollox, lol

 

[Andy™]

people probably think i'm talking a load of rollox, lol

you will fit in well here

 

[Lurch]

you will fit in well here

That's a weird thing to say.

 

[Murdoch]

Back to the OP - what was the purpose of the testing - new work? modified circuit? EICR?

 

[Tony S]

Do you have a resistance check box? I’d try the meter on that first to discount any problems it may have.

Other than a faulty meter, I don’t know what to suggest.

 

[Tony S]

I’ve just had another wavy brain. How long did you keep your finger on the test button?

 

[Barx]

Back to the OP - what was the purpose of the testing - new work? modified circuit? EICR?

EICR - I wasn't alone before anyone states incompetance. The other guy couldn't explain it either.

Do you have a resistance check box? I’d try the meter on that first to discount any problems it may have.

Other than a faulty meter, I don’t know what to suggest.

I didn't have one with me at the time, but I will certainly test the meter on one at various ranges.

I’ve just had another wavy brain. How long did you keep your finger on the test button?

hmmmm, not sure. With the tester I was using it is a press and let go, then it does it's own thing in it's own time. Not a press and hold job. Though my thumb was probably resting on the button. Make sense? lol

 

[Andy™]

maybe the other guy was elsewhere playing with a variable resistor whilst you were testing?

 

[apprentice87]

So far as i know, there is a standard time to press the thing for, one minute..

john..