Where the Grid Comes In [/ˈwɛr ðə ˈgrɪd ˈkəmz ɪn/] n - The service entrance is the point where the electric utility’s wiring meets the data center’s own distribution. For any facility larger than a closet, power arrives at medium voltage (typically 11–35 kV) rather than at the 400/480 V used within the building, for higher voltage means lower current, and far smaller, cheaper conductors for the same power.

At or just past the entrance the utility’s feed lands upon Medium-voltage switchgear, which furnishes metering, protection, and the means to isolate the building from the grid. Large sites take two utility feeds from different substations, so that the loss of one feed is not the loss of the site: the first and cheapest layer of Redundancy topologies.

From the switchgear, transformers step the medium voltage down to the The Current That Comes in Threes low voltage that the rest of the plant, Uninterruptible power supply, Power distribution unit, and so on, actually uses. The quality of the Grounding and bonding established here sets the reference for the entire downstream system.

Part of The Engines of the Hall.