The basic part of the electricity fee is not charged, and generally it is enough without large electrical equipment. The excess depends on the reason. If it's air conditioning in the dormitory, everyone enjoys it and shares it equally. If it is obvious that individuals use too much electricity, they will pay for it.
In fact, it is usually a very short time. It is often that everyone takes turns to pay when they have time, and the electricity consumption is similar, just computers, desk lamps and chargers.