Low earth leakage tripping current

[SeanM]

Morning all

I had a fault last week where the earth leakage tripped intermittently, so I arrived tested the earth leakage and tripped at 16ma. This is low so before changing I continued to test and found that the customers motor had condensation on the terminals. Dried out and all ok.

I then proceeded to changed the earth leakage as I would like it to trip between 20-25ma and to my surprise any earth leakage I tried still tripped at 16ma.

Any ideas the reason for this?

[Justloadit]

Morning all

I had a fault last week where the earth leakage tripped intermittently, so I arrived tested the earth leakage and tripped at 16ma. This is low so before changing I continued to test and found that the customers motor had condensation on the terminals. Dried out and all ok.

I then proceeded to changed the earth leakage as I would like it to trip between 20-25ma and to my surprise any earth leakage I tried still tripped at 16ma.

Any ideas the reason for this?

Maybe the measurement instrument is faulty or has a flat battery?

[GCE]

Can also be that there are various loads plugged in and leaking slightly to earth , like 4 to 9 ma leaking.
Your tester is then just adding to the leakage and the unit only needs another 16ma to trip

If you connected the tester directly to the earth leakage without any other load you may find it then trips at 20-25ma.

[ians]

Spend the money and buy a leakage current clamp meter....they cost around 5 k ..best money other than my fluke 1653 i have ever spent.

I was called in by a company to do power quality checks where a company had done a new installation...there were 12 transformers feeding the building (big industrial site in Newcastle)...as they pressed the start button every leakage current detector tripped...a room full of engineers and electrical contractors couldnt figue out why ...i connected my fluke 435 to one of the panels ...I personally didnt think it was the VSD's causing the problem...however they were paying me to do a power quality check...I took out my leakage current clamp and put it on the earth conductor...imagine that...readings indicated that there was a bad earth...i climbed under the building and checked the earth grid...it had been stolen...replaced the earth grid and all the bonding and bingo...problem solved.

The tester can be used to identify which wire and circuit is the problem without pumping a 500 volts into the electrical installation using an insulation resistance tester... we all know what happens if you dont disconnect and remove sensitive electronic equipment.

[SeanM]

Greetings All

Thank you for the comments at least I know I haven't lost the plot.