Rack PDU

A rack PDU, short for power distribution unit, is the rack-mounted strip that feeds every server, switch, and storage shelf in one cabinet from one or two upstream circuits. Most mount vertically in the rear channel, taking no usable U, though 1U and 2U horizontal models exist. The unit splits a single high-amperage feed into the individual outlets each device plugs into.

Basic models are outlets and a breaker. Metered units add a local or networked reading of current draw per bank. Switched units let an admin power-cycle one outlet remotely, which saves a trip when a server stops answering. A common unit is rated 30 A at 208 V and carries 24 to 48 C13 and C19 outlets. That circuit supplies about 6.2 kVA, and continuous load is limited to 80 percent of the rating, so budget roughly 5 kW per unit.

Size to measured draw plus headroom, not to the sum of the wattage printed on every power supply, since that total assumes each one runs flat out at once. Outlet count is rarely the constraint. A dense GPU cabinet usually needs two or three circuits with matching PDUs rather than one large one.

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Last verified August 29, 2026.