Usage of common property utilities (power, water)

I am wondering what is the rule, if any, regarding use of a building’s (or in my case, townhouse complex) power and water. The example is use of the common property power from the general garage by builders for power tools when cutting timber or tiles for an individual lot owner’s internal renovations. We (the EC) claim that they should use power from their own unit, which is possible with the use of leads or they do it on the property. The power outlet is adjacent to the car-wash area in the garage and is clearly intended for that use – cleaning and vacuuming of resident’s cars.

Any thoughts please?