Andy Burns wrote:
NY wrote:

I'm used to seeing three-wire (three phases) overhead mains wiring from
poles along a street.
But I'm mystified about five-wire mains.

TN-S system (not TN-C-S)

L1, L2, L3, N, PE

What happens with TN-S if you are fed from a pole? Do you get a separate
earth conductor, or are they all TN-C-S or TT?

One possibility in the OP's setup is it's TN-S because it goes to a buried
cable somewhere, and the earth is to earth the cable sheath.

Theo