dscrepency between notrp and hi

[crabapple]

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ive noticed when doing loop tests, there s a slight diiference between notrp(i think its 15 ma) and hi which sends out about 20a

is it just me??

 

[MarkieSparkie]

No mate it's a common occurrence.
In lab conditions both No-Trip and Hi loop test measurements are likely to be similar, certainly within the accuracy of the MFT, but add in the oxidized joints of a typical real world installation and result is likely to be completely different. My money is on the Hi current loop test giving the more accurate result because the higher current is likely to be able to break down the oxide or tarnish film.

 

[IQ Electrical]

Also if there are any connected loads or 'noise' on the circuit, the difference in readings is even greater.

 

[somersetsparks]

The old robin loop tester I have will give you textbook readings when testing an old install! My megger on de-lock is will regularly give readings of 0.8 on a socket where the robin will give you 0.3!
Usually if you push the plug in and out a few times readings improve.

 

[Guitarist]

There have been loads of posts on this subject recently. Just search for megger 1700 series.