Testing Connection of Single-family House Installation to 3-phase RCD with One Phase Input

Hello.
I am just finishing the construction of an installation in a single-family house. Everything is connected, the meter does not show any short circuits.
Electricity for the construction site is borrowed from a neighbor (via an extension cord). Now I'm wondering whether before taking measurements and connecting the installation to the network, test it "hot", i.e. connect electricity from the neighbor to the fuses.
And here comes the question about the residual current protection: will it not be damaged if I short-circuit the phase inputs into one phase at its input and then connect it to an extension cord (plus the N wire, of course)?
Theoretically, it should work, but I'm not sure whether such a differential doesn't somehow check the phase shift and may be damaged if we connect the same phase everywhere...
The following questions are: all sockets and switches are connected, I have an SEP up to 1kV (of course the lowest one, maintenance and operation).

That's what I meant, thank you.

I checked the continuity of the wires. I only checked the insulation resistance at 100V (telecommunication network meter, I don't have another meter). There may be no point in checking such a connection, but there is another point: it is getting dark outside faster and faster, and there is still a lot of finishing work left, and making light would make such work much easier. I don't know when the electrician will arrive to take measurements, and you'll probably have to wait another month to connect it if they kindly come.

Added after 1 [hours] 54 [minutes]:

Anyway, thank you for your answer and "concern". My main concern was whether to connect it before the differential or, better yet, after it.

Next time, please refrain from commenting on us by placing them in " " . I'm closing the topic. [kkas12]