Fluke Insulation Resistance No Reading

[notoriousgib83]

Hi,

I was wondering if anyone has come across this before. I was doing an insulation resistance test on a property practising for my periodic exam. I set the tester to 250v because I couldn't remove all equipment, when I went to test across the live conductors and CPC I didn't get a reading and the tester only 'ramped' up to 4v.

When I got home and tested it on my test rig the tester ramped up and took a reading as normal. Any ideas what could have caused this?

 

[telectrix]

silly question but are you sure you isolated the circuit under test?

 

[notoriousgib83]

I'm pretty sure I isolated everything accordingly, I performed safe isolation and 'attempted' to perform a full board test. Would you recommend performing a test on individual circuits if this problem occurs.

 

[tony mc]

Sounds like your tester is detecting voltage !!

 

[notoriousgib83]

Really, I can't see how that can be, I performed safe isolation using a GS-38 proving unit and voltage tester and the installation was dead.

 

[tony mc]

Post the model of your fluke so some one with knowledge on the tester can reply.

If doing a insulation test the reading should be Meg ohms not volts so if it reads volts what is the tester picking up??

My tester will shut down and give a warning if voltage is detected and not alow you to test..

 

[notoriousgib83]

Hi,

It's a Fluke 1562. The tester is getting a reading of 0.00 Meg ohms and when I mention voltage the tester shows what it has 'ramped' up to. It should be ramping up to 250v as that is what I set it to, but it is only ramping up to 4v.

Any suggestions would be much appreciated! cheers,

Andy.

 

[sparkx]

well the meter is quite clearly giving you a reading - a reading of 0.00 Mohms. I suggest there's a fault in the circuit somewhere.

 

[telectrix]

what i do once a month is IR test a 1 Meg. resistor. then i know the meter is right.

 

[notoriousgib83]

well the meter is quite clearly giving you a reading - a reading of 0.00 Mohms. I suggest there's a fault in the circuit somewhere.

Well no it's not because it's not testing at voltage. If it ramped up to 250v and I got 0.00M ohms then yes I'd agree, but the highest it got to was 4v.

Thanks, telectrix that's a good suggestion.

 

[yellowvanman]

What has happened is that the tester can't apply the 250V because there is a low resistance between the test leads, I would suggest that whatever you can't remove is soaking up the energy the tester is trying to apply to the circuit, henmce the low voltage.

If the reading is between L-N then clearly something is on, if its between L-E then its getting to E through the neutral route - disconnect both L & N from the CU and try again.

 

[notoriousgib83]

Brilliant, I'll give that a try. Thanks for the help.