Hi,
I end-up with this configuration.
- line filters for room input grid cables.
- optical ethernet cables
- big metal plate for the test setups
- Reliable PE
- last but not least - setups runs on many 200Ah/LiFePO4 cells. See picture below for one +-12V setup configuration. Battery packs are independant (floating). It reduces the headache with grounding.
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All it begun 30 years ago with introduction of switching power supply in home appliance.
It started with TV, computers and end with PV inverters, washing machine and LED lighting, WiFi did not make life easier too.
PS: Isolation transformers did not worked for me. They had huge leakage capacitance