Thank you for your reply.
The electricity is not free, but it's included in the rental price of my appartment. I do know it's forbidden to run servers but that's because of fair use of the network (internet is also included in rentalprice).
There is only 1 meter for X amount of apartments so what I, or any other tennant, use more than the average is always considered to be coming from a pool of X unidentified apartments. Two S5's running 24/7, or two sp20's ftm, will not be noticed. Also: I (pre)paid to use a certain amount of electricity and as long as I stay under max usage, noone cares.