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Joined: Jun 2014
Posts: 128
D
dsk Offline OP
Member
Originally Posted by dsk
The reason are probably in another part of the building, and the combined breaker of the trade mark Chint, was renamed by one I do not know, but overheard calling it Shit. It may be right renaming, but I am not 100% sure. :-)

I do not believe so, but it may just be bad English from another Norwegian :-)

Another trust-able electrician tells me that other makes has almost the same error rates too.

Joined: Jun 2014
Posts: 128
D
dsk Offline OP
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Originally Posted by Trumpy
dsk,
Are you really sure that that is the issue though?
Have you tested the actual earth leakage circuit breakers to rule them out?
What voltage and size pump motor is it that caused this fault to occur?
I find it very strange that a single motor could cause multiple RCD's to trip at any given time,
unless there is an issue with the neutral-earth link at the switch-board or some other poor
neutral connection somewhere in the system.
Anyone doing electrical work these days should have at the very least one of them either Fluke,
Kyoritsu or Megger multi-function testers, they give you so much in the way of things you can test.
My Kyoritsu tester allows me to upload to my laptop and it's instant test records.
I have insulation resistance to 1000V, Earth-Loop, Continuity, Earth Resistance (2P, 3P), RCD Tester.
You only have to buy it once.


They have some pretty impressing testers, but I do not know how well they know how to use it. Our supply here is an really old system called IT witch is a delta transformer with absolutely no point connected to ground/earth, only 3 wires with 230V between each. (like your 208V system, but no neutral to gnd.)
The motor to the pump is rated only 21 Amp. The main breaker for the building is on 2500A !!!

IT system: https://www.electrical-installation.org/enwiki/Characteristics_of_TT,_TN_and_IT_systems
These systems will not be used in new systems, but here we keep them up and running so far.

When testing the insulation between line and ground on the loops that is tripping it has always been more than 7 mega-ohms at 1 kV. The tester tells that the GFCI marked 30 mA release at around 17mA

I am not a certified electrician, only an engineer. The owner of the building does not allow me to do anything my-selves.

In earlier jobs I have designed, and built equipment that has been officially approved. Among that, equipment needed for building the Oakland San Fransisco east span bridge. That is why I may compare US and Norwegian systems.

Last edited by dsk; 11/05/21 06:47 AM.
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