This is entirely an US problem created by the “center tap” nonsense. Nobody else I’m aware of uses that, let alone with that other. The outlet in question (type F) I’m only aware of being in use with one phase of a there phase supply plus the neutral, or just “the” phase and neutral. Note that in the second case, even if a house or apartment only has one phase wired to it, it’s still generally part of a three phase supply, but the other phases just aren’t wired to that particular place (incredibly rare these days, but might be the case for very old homes/installations).
Now the real reason for it being safe: The neutral is required to be wired to ground at the main breaker panel. With installations newer than 2000-something, every circuit has to be GFCI protected. With even newer installations having even more granular requirements (not sure on the specifics).
in many flats even recently built you don’t get three-phase power, just single phase, but building divides single three-phase supply into three groups of single phase circuits like you say (do you really need 20kW in residential flat? one that doesn’t use EV charger, built in 90s-10s?) i guess it depends on country also. separate houses tend to get three phase connection where i live
floating neutral will also be a problem in american-type two-phase installation, might be even worse (more frequent) on account of large number of lightly maintained transformers used (why on gods green earth there’s few-kV medium voltage line going down every street, americans make it make sense)
This is entirely an US problem created by the “center tap” nonsense. Nobody else I’m aware of uses that, let alone with that other. The outlet in question (type F) I’m only aware of being in use with one phase of a there phase supply plus the neutral, or just “the” phase and neutral. Note that in the second case, even if a house or apartment only has one phase wired to it, it’s still generally part of a three phase supply, but the other phases just aren’t wired to that particular place (incredibly rare these days, but might be the case for very old homes/installations).
Now the real reason for it being safe: The neutral is required to be wired to ground at the main breaker panel. With installations newer than 2000-something, every circuit has to be GFCI protected. With even newer installations having even more granular requirements (not sure on the specifics).
in many flats even recently built you don’t get three-phase power, just single phase, but building divides single three-phase supply into three groups of single phase circuits like you say (do you really need 20kW in residential flat? one that doesn’t use EV charger, built in 90s-10s?) i guess it depends on country also. separate houses tend to get three phase connection where i live
floating neutral will also be a problem in american-type two-phase installation, might be even worse (more frequent) on account of large number of lightly maintained transformers used (why on gods green earth there’s few-kV medium voltage line going down every street, americans make it make sense)