IR readings Puzzeled

[ianphilip007]

hi there

carried out IR test on radial lighting circuit today. L-N 700MOhms N-E 650Mohms L-E 320Mohms just wondered why the L-E would be nearly half the value ???? ( test carried out at 500v dc, TNCS system circuit disconnected at board)

 

[ipf]

I wouldn't really worry, 320 million ohms isn't too bad a reading, is it.

 

[TaffyDuck]

320 meg Ohms is still massive, my Megger would just say >299Mega Ohms so hardly anything to worry about. A tiny thinner bit of insulation would account for it or perhaps a little moisture.

 

[ianphilip007]

can anyone think of a reason as to why ? . Not too concerned as even at 300Mohm is a high reading just puzzeled as to why it was so much lower than the other two readings

 

[sctp]

hi there

carried out IR test on radial lighting circuit today. L-N 700MOhms N-E 650Mohms L-E 320Mohms just wondered why the L-E would be nearly half the value ???? ( test carried out at 500v dc, TNCS system circuit disconnected at board)

Like Ian said 320Mohm is good. Was that with earth disconnected at cu? I've had some false readings when earth left connected with L and N disconnected...

 

[ianphilip007]

yes i agree taffy/ipf nothing too worry about, 300Mohms is a very high reading, just puzzeled me a little with it being a lot lower,

 

[telectrix]

jeez. it's like the captain of the titanic worried about the temperature of the 1st class swimming pool when it hit the iceberg.

 

[ianphilip007]

no earth was disconnected same for neutral and live too for said light circuit.

 

[ianphilip007]

lol i know telextric as ive said just puzzeled me as to why it was so much lower, no concern re the actual reading that was very good.

 

[telectrix]

if you breathe on the leads that can give you less than 300M.

 

[Edd]

maybe you squeesed the crocodile clip harder when doing the L-E test..

 

[Knobhead]

Moisture in the air can give differing readings. Just about anything you can think of will give a variance.

To give you an idea I used to have to test a motor every week at 5KV DC. The records had a column for weather conditions. Like the Top Gear test track, it makes a hell of diference.

 

[ianphilip007]

lol thanks for the replys guys

 

[telectrix]

Moisture in the air can give differing readings. Just about anything you can think of will give a variance.

To give you an idea I used to have to test a motor every week at 5KV DC. The records had a column for weather conditions. Like the Top Gear test track, it makes a hell of diference.

as long as it's not that idiot clarkson doing the testing.

 

[Brightspark2]

Because them 2 conductors have a lower insualtion resistance....


All readings wont always be the same in a circuit...

 

[UNG]

If you are looking for reasons why they vary so much

Then check how good the batteries are in the meter, if they are ok then check the test leads had quite a few which failed at the plug through the continuous flexing they get

 

[telectrix]

maybe thayt's why my joints are failing... all this flexing.... not just bending to pull cables, but lifting beer as well.