Different readings for residual (differential) and leakage current

[dangerousamateur]

Recently I was given the task of doing the anular electrical safety check by my employer.
I've been doing this before at a different place, with other equipment ect. but somehow never faced the following riddles.
One never stops learning I guess




Scenario 1:
Metrel Multi Servicer MI2170
Vacuum cleaner, Class II, mint condition

There is no PE connection, the device is was placed on a wooden table.
The vessel with the filter is made of metal, the rest is plastic.

Insulation check against the metal vessel gives fullscale reading.
Residual(Differential) leakage current is 0,04mA
Touch leakage current is 0,65mA
Putting the probe on the metal makes no difference.


My understanding is that the touch current displayed is the combined value of PE and probe touch current.


Now I would like to understand as exactly as possible how this high reading exactly happens?
I tested several identical devices, they all showed the same values and are obviously OK/like the manufacturer made them...



Scenario 2:
Metrel Multi Servicer MI2170
Electrical heating radiator, looks like this one:
https://i5.walmartimages.com/asr/79ad3433-6e09-46dd-9f6c-2d75a539d0e3_1.dba027773b028baee6caa9f7cd767949.jpeg

Class I, PE connection is fine.
The device is was placed on a wooden table. Absolutely dry.

Insulation check gives fullscale reading.
Residual(Differential) leakage current is 0,02mA
Touch leakage current is 0,87mA


Heating Elements can cause significant leakage currents, that is known to me. Also I tested similar devices with the same results.

But how would you explain these contradicting values?
There is no other connection to earth than the PE!

[dangerousamateur]

I decided to give this a bump, maybe somebody has some thoughts to this.

[mzzj]

Best guess your tester is broken on touch leakage current function.

Does it also show leakage current even if you don't have any equipment connected to it?
when was it calibrated and were the results ok on touch leakage?

for giggles you could also try turning the tester plug 180-degrees on the wall outlet to see if it has something to do with phase-neutral order.

[mendip_discovery]

Do you have a 0.5, 1 and 2 MΩ resistors?

https://www.seaward.com/gb/support/download/365/
Page 9 shows the readings you should get for a given mains voltage.