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Joined: Jun 2014
Posts: 123
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dsk Offline OP
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Got the responsibility for a 100 yrs old building, The elctric systerms was rewired at lo cost 15 yrs ago. When I com in the morning at least one, sometimes 15 FFCI had don their job... but all measuring shows nothing wrong.

We have a 230V 3 phase supply quite equal to US 208V delta systems. (I'm in Norway) All this is wired for 230V single phase.

All hints to find and make documented reports are welcome.

Joined: Jul 2004
Posts: 9,667
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G
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If you have access to a power line monitor it might be worth a look but I am not really sure what kind of transient would trip multiple GFCIs. I assume the building is empty at night and you don't have a cleaning lady walking around plugging in a bad vacuum cleaner until she finds one that works.


Greg Fretwell
Joined: Jun 2014
Posts: 123
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dsk Offline OP
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I do only have a regular multi-meter, no power line monitor. And yes the building is empty during the night :-) Nice weather, no lightning.

Joined: Jan 2018
Posts: 26
L
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Any animals or insects around at night that could access wiring?

Joined: Jun 2014
Posts: 123
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dsk Offline OP
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No, none that I have seen, or tracks after insects or animals. it is turning to be colder now, and I have to be extremely aware of rats and mice that would prefer to live indoors during the winter, but no signs so far.
Large green area close to the building, pretty moist ground there now after day of raining, but that's after the the faults.

Discovered and fixed an error where 2 small branches was interconnected! Horrible error probably made when the building was rewired 15 yrs ago. After solving that no more errors in that sub-panel. The electrician could not understand how an error like that could have been there for so long without being a greater problem. At least it has been there since I came there in April.

Joined: Jul 2004
Posts: 9,667
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G
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One thing I learned as an inspector is installers seldom make one mistake if they are making mistakes. It is worth inspecting each circuit you are having trouble with paying particular attention to the neutrals. Folks tend to get sloppy with them assuming they are grounded conductors, what could go wrong but if they get grounded or share current with another circuit on the load side of a GFCI/AFCI it will trip. You may find multiple problems once you start looking but you have to start somewhere..


Greg Fretwell
1 member likes this: dsk
Joined: Jun 2014
Posts: 123
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dsk Offline OP
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Today I i made a ground fault extension cord...I did switch the live and ground, plugged in an old (double insulted, un-grounded so it should be safe to touch) drill an did some testing, and at least in 2 positions both the actual GFCI-breaker and one more did trip. Maybe induction, because it did not happen each time.


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