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Discuss Megger loop impedance irregularity in the Electrical Tools and Products area at ElectriciansForums.net

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Hi,

I have a Megger mft1720 and the low current loop test isn’t working properly. Just wondering if anyone else has had issues?
Readings are stupidly high compared to the high current test, and this can be made even worse if there’s an rcd in line......
 
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Midwest

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Arms
Esteemed
RCD's can cause issues; what leads are you using, has the unit been calibrated recently?
 

Strima

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Arms
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RCD uplift is a known issue when loop testing. If your R1+R2 is good and so is your Ze then just add both together.
 
  • Thread Starter Thread Starter
  • #5
Thanks for quick replies guys. Was using original Megger leads and bought a new cheap set to try out as well. Have been testing domestic stuff and never used to have a problem. For example today high current Ze was 0.16, r1+r2 for cooker circuit was 0.24. Low current Zs was something like 2.25!!
I have been adding Ze + R1+R2 together for my certs but only as I have no choice atm. Calibration not due til October.
 

telectrix

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Mentor
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cotton bud with switch cleaner on the 4mm sockets. also check no-trip ZS using 1363 plug lead, see if that's high as well.
 

SparkySy

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I had the same issue with my megger a couple of weeks ago, turned out that although the neg lead looked like it was fine it had detached slightly inside the probe end and would still work if you pushed the lead into a terminal but give a high reading, I finally realized when I put a crock clip on it and tried to loop at a light and it kept saying no neutral connection! It really bugged the [email protected] out of me all morning thinking me tester was kaput and would have to get it repaired, it was only calibrated 2 weeks previously!!
 

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