We have a problem with FIDS (RCCB) randomly blowing, different cabinets, not connected at all. Trying to solve it for few months now with army of electricians... So far, we have measured 4000A occurring on the neutral sometimes, sometimes sinus wave is getting almost flat for a moment and then get's back to normal. Outside the building difference in the potential is 150V.

The building is for approx. 300 people, with metal facade, 4 different groundings. There is basically no exact pattern, could be from personal observation that when it is sunny outside things got much worser. Building is now 3 years old. Basically, there were no changes when problems started.

So far, electrical distribution company connected us to different source to rule out that option. Also tried to disconnect from electrical distribution power company at all and used diesel generator (but groundings were the same). Tried to disconnect department by department, disconnect different appliances like climate, lights,.. and blow-outs still occur randomly.

Any ideas? Can metal facade produce static electricity and we have bad groundings? Maybe even somewhere inside building connected ground and neutral?

Thank you for your answers in advance.

  • 1
    \$\begingroup\$ Sorry, what is "FIDS" abbreviation for? \$\endgroup\$
    – user288518
    Jun 19, 2021 at 6:41
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    \$\begingroup\$ Have you installed a history datalogger for all currents and voltages main supply when problem occur ? \$\endgroup\$
    – user288518
    Jun 19, 2021 at 6:48
  • \$\begingroup\$ RCCB - Residual Current Circuit Breaker (FID). Yes, main supply is fine. Electrical distribution company is measuring quality. They even switched us to different main supply. We have tried disconnecting the main supply and connecting the diesel generator... \$\endgroup\$
    – Eips
    Jun 19, 2021 at 6:52
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    \$\begingroup\$ Should this be migrated to home improvement? \$\endgroup\$
    – user57037
    Jun 19, 2021 at 6:58
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    \$\begingroup\$ "4000 A on the neutral ..." Your question is missing details of the supply voltage, number of phases, nominal current per phase and where the neutral to earth connection is. Your user profile says you are in Germany so I'm guessing 230 V, 3-phase, 50 Hz. Where are you measuring 150 V? \$\endgroup\$
    – Transistor
    Jun 19, 2021 at 8:12

1 Answer 1


Static electricity won't generate enough power to do anything much.

If there is a lot of structural metalwork in the building, and it's heating up and cooling down during the day, then maybe it's a random intermittent short circuit between the wiring and the metalwork.

  • \$\begingroup\$ Thank you for the answer. Could be, as there were actually two earthquakes near with magnitude > 5 when those blackouts started. Well, not exactly after the earthquake but after 2-3 weeks, but yeah when weather was getting warmer. Basically, part of the building is without electricity sometimes for 10 minutes, sometimes for few hours. Problems are much worser now when we have warmer weather. \$\endgroup\$
    – Eips
    Jun 19, 2021 at 13:12
  • \$\begingroup\$ Just not sure as all the wirings are shielded... \$\endgroup\$
    – Eips
    Jun 19, 2021 at 14:18
  • \$\begingroup\$ a random intermittent short circuit between the wiring and the metalwork would imply a fault in the same circuitry., which is not what is observed. \$\endgroup\$ Jun 19, 2021 at 18:45

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