How to connect a bathhouse to electricity from home

Good day! What is the problem? Who are you going to ground? Phases?? Or is it PEN? Do you have grounding now and you want another one? Your business, but if you already have a ground electrode system, then you don't have to do another one.

You need to put a separate circuit breaker to protect the line on the bathhouse in your switchboard, 25A will be enough, with this cable section.

Install another shield in the bath, in which to install an RCD or difavtomats. There is no specifics in your question, "how is it right" depends on the fact that you will feed in two whole phases in the bath. I believe that some kind of electric furnace, then you protect it with a separate difavtomat or a bundle from a conventional machine and an RCD. The lighting in the steam room is best done with 12 volts. We published an article about the assembly of the electrical panel, maybe it will be useful to you https://samelectrik.ru/instrukciya-po-sborke-trexfaznogo-elektroshhita.html

You can equip the earthing switch for re-grounding the zero using a modular grounding kit - on today this is the simplest option, and you will get a fairly reliable and high-quality result on exit. Such kits are produced and sold by many companies, I cannot single out individual manufacturers. Or do it the old fashioned way - by driving 3 corners into the ground. In this case, the grounding will be the better, the larger the surface area of ​​these corners and the deeper they are driven in. At home, you cannot check the grounding resistance, so you cannot make a really high-quality ground electrode system. The only option is to make a deliberately redundant structure, for example, drive three corners as wide as possible or 2-2.5 meters thick pipes into the ground. But it's time consuming. It is better to turn to those who can make grounding that meets the requirements of regulatory documents.