Wetroom Store - Network Wetroom Suppliers
This official sponsor may provide discounts for members

Discuss IR testing - results creep up! in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

P

pencilpusher

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:  American Electrical Advice Forum

Hi all

Why is it that on some circuit IR testing, the results shoot up to say 250 M ohms but then creep up towards a much higher value? I know that the results are OK, I just thought it may be some damp somewhere causing the problem possibly. Do you wait for them to stop creeping up or take a result after say 5-10 seconds.

Any views would be welcome.

PP
 
Instyle LED Lighting Specialists UK
This official sponsor may provide discounts for members
P

pencilpusher

  • Thread Starter Thread Starter
  • #3
Yeah sure, I was just curious why sometimes this happend and other times you get >999 M ohms very quickly.

PP
 
E

Engineer54

  • Thread Starter Thread Starter
  • #5
Do you wait for them to stop creeping up or take a result after say 5-10 seconds.


Not that many electricians do, but the correct way to record a IR value is after 1 minute, (in most cases). Which allows the test voltage to charge the complete circuit and find any weak spots in the insulation. A quick 3 to 5 second push of the test button, is not and never has been the correct procedure...
 
I've normally found dampness to cause this.
 

spark 68

-
Arms
Esteemed
With otherwise good high readings I agree dampness can cause fluctuating readings, but a slow creep up I always thought this was due to capacitance effects, and thought this was the circuit just charging up.
 
Last edited:
With otherwise good high readings I agree dampness can cause flucuating readings, but a slow creep up I always thought this was due to capacitance effects, and thought this was the circuit just charging up.
Absolutely, a bit of capacitive coupling on long runs!
 
P

pencilpusher

  • Thread Starter Thread Starter
  • #10
[/COLOR][/LEFT]

Not that many electricians do, but the correct way to record a IR value is after 1 minute, (in most cases). Which allows the test voltage to charge the complete circuit and find any weak spots in the insulation. A quick 3 to 5 second push of the test button, is not and never has been the correct procedure...
So one minute it is then, unless I get >999 M ohms immediately of course!
 
1

1shortcircuit

  • Thread Starter Thread Starter
  • #12
If I notice this, which I have in the past, I continue to keep the test button pressed in on my Fluke tester until it bleeps and enter the final figure displayed:thumbsup
 
E

Engineer54

  • Thread Starter Thread Starter
  • #13
If I notice this, which I have in the past, I continue to keep the test button pressed in on my Fluke tester until it bleeps and enter the final figure displayed:thumbsup
Be thankful your not Hi Pot testing MV/HV cables (basically the same thing but at much higher voltages), that can be anything from 15 to 30 minutes, depending on if it's initial verification or for subsequent verification after an incident for arguments sake. As Hi-Pot tests are classified as a destructive test, often both test KV and times are reduced....
 
1

1shortcircuit

  • Thread Starter Thread Starter
  • #14
anything from 15 to 30 minutes
lol

I imagine holding the test button for that length of time would be similar to holding the lever on a hand-grenade with the pin removed lol
 
P

pencilpusher

  • Thread Starter Thread Starter
  • #15
Well there is nothing to say it can't also slowly reduce during that minute!! lol!!!
Maybe, but if it slowly reduces to 300 M ohms, I am still quids in aren't I? !! :drummer:
 
Last edited by a moderator:
Test Meter - Forum Sponsors since 2007!
This official sponsor may provide discounts for members

Reply to IR testing - results creep up! in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

CK Tools :) The professionals choice when it comes to Electrical Tools
This official sponsor may provide discounts for members
Top Bottom