This is volts-to-earth sociology, unrelated to concealed pipe sweats unless water has already breached glands — cross-read plumber damp-vs-leak after you isolate shock risk.
Appliance chassis ties to CPC so fault current shocks the breaker instead of wrists. Bypassing boots on washing machines trades convenience for asymmetric risk.
Differential gear notices milliamps creeping wrong paths — great for immersion rods, punitive for leaky LED drivers clustered sloppily. Whole-home 30 mA religion sometimes needs circuit splitting by a licensed designer.
Letter soup matters when renovators carve new toilets and nick conduits. Document what your electrician actually measured across N-E bonds before aesthetic boxing hides everything.