ᐅ Run electrical wiring from the house to the garage

Good morning!

Here is the situation:

I have my house with a basement, and about 20 meters (65 feet) away there is a rather dilapidated existing garage that temporarily needs power until it is renovated in two to three years. I will hand that over to an electrician then.

During the construction phase, my electrician installed a standard 230V underground cable from the basement, which should be long enough. However, I’ve realized that 230V alone might not be sufficient.

In the utility room (basement, below the parking area), we have a 400V 32A outlet, installed simply to have it available and to allow easy later installation of a wall box in the carport if an electric car should come along.

Here is the idea:

The 230V underground cable goes to the carport for power and a normal outlet.

I want to bury a 400V cable as well. I will drill a hole in the basement wall, feed the cable through, and seal it with, for example, expanding foam used for well sealing. I will have a 32A plug installed on it and plug it into the outlet.

In the garage, I will also fit a plug and connect it to a portable construction power distribution unit. These units are splash-proof, made of gray plastic, have six standard outlets, and one 400V/16A plus one 400V/32A socket.

When the garage is finished, I will seal the 400V cable end in the basement with a resin joint, and have the electrician connect it into the sub-distribution board.

Will this work?

Am I allowed to put a plug on a cable like this?
Is this technically possible? I’m concerned the underground cable might use different wiring.

We have no groundwater issues, but is expanding foam sufficient, or should I do a core drill and use a compression ring seal? I think something like a Doyma seal might be overkill…

The temporary setup should work for about two years. In the garage, I will be using an angle grinder, lighting, a plunge-cut saw, and a wood splitter.

Thanks!