No reading for insulation resistance fluke 1652b

[Kay]

Was having a play with this new toy and found when measuring between phases on a ring final that this instrument didn't give any reading at all. It shows that it is testing but the readout on the annunciator never changes. However taking a reading between live conductors and earth gave a reading of > 500M Ohms. Looking at the spec sheet the maximum display value is 1000M Ohms @ 500v. So either the reading is outside this range or there is something amiss. I haven't had a chance to test any other circuits for comparison.
Any ideas?

 

[Guest123]

Measuring between line & line on a ring final will poroduce a dead short circuit (0.00Mohm) as they are the start and end of same conductor.

 

[Kay]

Hi Lenny,
thanks for the quick reply! Should mention that this test was for a single circuit and performed as per the OSG pg84 (test between line and neutral) According to the OSG table 10.1 IR minimum should be 1M Ohm between phases although a lot higher in practice. All sockets and FCU's were in open position. There should be a high resistance between phases in this situation.

 

[Guest123]

In your original post you stated you were testing between 'phases' on a ring final which translates to end to end measurement of the line conductor.

So what you have now is a radial circuit supplying some socket outlets and fused spurs??? and you are testing between line & neutral???

 

[Kay]

Sorry my mistake I'm confusing terminologies and definitions! I had it in my head that as the neutral is considered a live part or live conductor (although not the line) that it was also a phase which is obviously not right! Glad that's cleared up

However I was testing one end of the ring final at the neutral and line conductors and so expect to see a high resistance. No mention of radials though. Do you have a 1652b?

 

[IQ Electrical]

Are you testing 'through' an rcd?
This can affect your IR value and indeed damage the rcd.

 

[Deleted member 9648]

Was having a play with this new toy and found when measuring between phases on a ring final that this instrument didn't give any reading at all. It shows that it is testing but the readout on the annunciator never changes. However taking a reading between live conductors and earth gave a reading of > 500M Ohms. Looking at the spec sheet the maximum display value is 1000M Ohms @ 500v. So either the reading is outside this range or there is something amiss. I haven't had a chance to test any other circuits for comparison.
Any ideas?

So you are testing between L-N at one end of a ring...is that correct??......when you state 'no reading' do you mean a blank screen,or a reading of 0.00Mohm??......if the latter there is either a dead short or more likely a load still connected...if you have been applying 500v to that load and it includes electronics there is a fighting chance it will now be fried.

 

[telectrix]

So you are testing between L-N at one end of a ring...is that correct??......when you state 'no reading' do you mean a blank screen,or a reading of 0.00Mohm??......if the latter there is either a dead short or more likely a load still connected...if you have been applying 500v to that load and it includes electronics there is a fighting chance it will now be fried.

we used to call that " destructive testing"

 

[Kay]

Hey thanks for all the replies so far

IQ Electrical. No RCD's in this CU.

Wirepuller. Yes I'm testing between L-N at one end of the ring.The screen doesn't show a change other than it's in testing. Definitely not showing a low ohmic value. Made sure that all plugged in kit via sockets were not switched on (closed position) and all fcu's were left open so no chance of anything frying.

telectrix. ever got a customer to buy into that? "Sorry love your lamp blew 'cause it was dangerous and not up to the task anymore...lucky for you we found it just in time!"

 

[ezzzekiel]

although i havent used a fluke for some time it would appear to be a fault with the instrument if it cant take any reading either correct or showing dead.

 

[Goody]

Sometimes Fluke plays up if the batteries are weak!