Rack PDUs

Rack PDUs Buying Guide

A rack PDU, short for power distribution unit, gives every server, switch, and firewall in your rack a place to plug in, all fed from one circuit or a rack mount UPS. Horizontal models mount in 1U or 2U like any other device, while vertical 0U models run along the back of the cabinet and take no rack space at all.

What Are the Types of Rack PDUs?

Basic PDUs deliver power to every outlet and nothing more, which suits a small network closet with a switch, a firewall, and a patch panel.

Metered PDUs add a display that shows how much current the rack draws, so you know whether there is room for one more server before you trip a breaker. Monitored models send that reading over the network, and metered-by-outlet models report each outlet on its own.

Switched PDUs let you turn individual outlets off and on from a browser. When a switch or NVR locks up at a remote site, you can reboot it without sending anyone to the rack. Switched and monitored units are often called smart or managed PDUs.

Metered or Switched PDU: Which Do You Need?

Go metered if someone works near the rack and mainly needs to watch the load. Go switched for a branch office, a colocation cage, or any rack nobody can reach quickly. The APC AP7900B does both in 1U, with eight outlets you can reboot remotely and a local current display that warns you before an overload.

Running your network on UniFi? The UniFi SmartPower PDU Pro shows up in the same UniFi dashboard as your switches and gateways, gives you 16 outlets you can power cycle remotely, and adds four USB-C ports for small devices.

Which Plug and Outlets Does Your Rack Need?

Match the PDU's input plug to the receptacle feeding the rack. 120V PDUs provide standard NEMA outlets, while 208V PDUs provide C13 outlets for server power cords and C19 outlets for higher-draw servers and storage. Three-phase PDUs deliver more power from one feed for dense data center racks.

In North America, rack PDUs are derated to 80 percent of their plug rating for continuous use, so a 30A unit supports 24A of equipment. Pick up matching power cords for the outlet types you choose.

Redundancy for Critical Racks

Single-corded gear like a firewall can get a backup feed from an ATS PDU, which switches to a second input automatically if the first fails. Maintenance bypass PDUs keep the rack powered while you service or swap the UPS behind them.

Which Rack PDU Brand Fits Your Setup?

Eaton rack PDUs, including the Tripp Lite line, range from basic strips to metered input models that daisy chain four units on one network connection. APC NetShelter PDUs come in basic, metered, and switched versions in 0U, 1U, and 2U sizes. CyberPower offers switched and metered ATS PDUs for single-corded equipment. Vertiv Geist basic PDUs cover 208V server racks.

For AV racks, Middle Atlantic RackLink PDUs add outlet control over the network and can reboot a device automatically when it stops responding. StarTech 1U PDUs with front and rear outlets keep a small rack tidy.

Rack PDU FAQs

Do I need a PDU if I have a UPS?

Yes, once the rack has more devices than the UPS has outlets, or when you want load readings or remote reboots. A UPS keeps equipment running on battery, while a PDU only distributes power, so plug the PDU into the UPS and keep the total load within the UPS rating.

How many PDUs do I need per rack?

One or two. Racks with dual power supply servers use two, one on each power feed, so equipment keeps running if a feed fails. A smaller rack with single-corded gear can run on one, as long as its outlets and amperage cover everything plugged in.

Is a PDU the same as a surge protector?

No. A PDU only protects against surges when the model lists it, like Middle Atlantic and StarTech models with built-in surge protection or the Tripp Lite Isobar. Otherwise, pair it with a surge protector or a UPS upstream.

Is a PDU just a power strip?

Not quite. A basic rack PDU works like a power strip, but it mounts in the rack and comes in 20A and 30A models. Metered and switched models add load readings and remote outlet control.