I got a chance to visit one of the data center, I was searching for the power cables, there was none.

That may be because the power cables are below the raised flooring made up of 60 cm (2 ft) removable square tiles. These provide a plenum for air to circulate below the floor, as part of the air conditioning system, as well as providing space for power cabling. Data cabling is typically routed through overhead cable trays in modern data centers. Smaller/less expensive data centers without raised flooring may use anti-static tiles for a flooring surface.