A power distribution unit (PDU) is a device that takes power from an upstream source and makes it available at several outlets so multiple devices can connect to one feed. In IT environments, the term usually means a rack PDU, which consolidates the power cords of servers, switches, and storage equipment inside a server rack. A PDU distributes power; it does not generate it or add electrical capacity to the circuit that feeds it.
What a PDU does
Lenovo Press defines the device in its Lenovo 1U Basic PDUs Product Guide this way: “A power distribution unit (PDU) is a highly reliable, multiple outlet power strip designed to consolidate line cords within the rack and distribute conditioned power from an uninterruptible power supply (UPS) or utility power to servers and other IT equipment.”
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In practical terms, a PDU receives power through one input cord and feeds it to a row of outlets. Without one, every server in a rack would need its own run to a wall receptacle or a long chain of consumer power strips, which is hard to manage and easy to get wrong. The PDU keeps those connections in one organized, rated unit.
A PDU is limited by what feeds it. Its ratings, the upstream outlet, and the building’s electrical circuit all set the ceiling on how much equipment can be powered. Connecting more devices to a PDU does not create more power, and an overloaded PDU or circuit is a safety problem regardless of how many outlets are free.
#1 Best Overall
- POWER AND CHARGE: This rack mount power strip provides an additional 8 NEMA 5-15 outlets (120V/15A) and features a 6ft (1,8m) long cord so you can plug your devices in while leaving the rack mobile
- 1U RACK DESIGN: Compatible with all 19" server racks 4 inches or deeper, this horizontal-mount power distribution unit fits many network racks and has an integrated power cord; ANSI/EIA RS-310-D standard
- EASY INSTALLATION: This IT-grade rackmount PDU features a rugged steel chassis, LED indicators for ground and surge protection, and lets you control the power state with power and reset switches
- PROTECTS YOUR EQUIPMENT: This rack mountable 8-outlet (120V) power strip features a built-in circuit breaker and reset switch, ensuring a dependable performance of your networking equipment
- THE IT PRO'S CHOICE: Designed and built for IT Professionals, this rack PDU is backed for 2-Years, including free lifetime 24/5 multi-lingual technical assistance
PDU, UPS, and power strip: how they differ
- Power strip: a consumer or office outlet extension. It usually lacks the rack mounting, rating, and build quality expected in data-center equipment.
- PDU: a distribution device that takes power from an upstream source and feeds many outlets. It has no energy storage.
- UPS (uninterruptible power supply): a source that keeps power flowing during an outage or disturbance, using batteries or similar storage. A PDU is often fed by a UPS, and the Lenovo definition above names the UPS and utility power as the upstream sources.
Types of PDU
Vendors group PDUs by features rather than by one shared standard, so the labels below are a general guide. Eaton’s power distribution units for server racks page and its rack PDU buying guide describe the basic, metered, and managed categories, and Schneider Electric’s rack PDU range uses similar distinctions.
| Type | What it does | What to confirm before buying |
|---|---|---|
| Basic | Distributes power to multiple outlets with no load measurement or remote control. | Input rating, outlet count, and plug type. No monitoring is provided. |
| Metered | Displays load locally, measured at the input, a load group, or individual outlets depending on the model. | The measurement point. “Metered” alone does not say whether you get per-outlet data. |
| Monitored | Adds network-based visibility into load and environmental data. | Whether monitoring is local or remote, and exactly which values are reported. Vendors do not use this term identically. |
| Switched or managed | Adds on/off control for individual outlets, usually with monitoring. | Network setup requirements and the access controls for remote switching. Remote power cycling should be used carefully, because switching off the wrong outlet can take down a live server. |
| Automatic transfer switch (ATS) PDU | Moves a single-corded device between two power sources if the primary source fails or becomes unstable. | Compatibility with both sources. Not a general replacement for a UPS or a redundant facility design. |
| Hot-swappable PDU | Has dual AC inputs with manual transfer, so a compatible UPS can be serviced or replaced without interrupting connected equipment. | Exact product compatibility and the installation instructions for that model. |
Because labels vary, the specification sheet is the authority. Two products both described as “monitored” can report very different data, and a “metered” unit may only show total input current.
Rank #2
- 10 NEMA 5-15R Outlets with Long Power Cord: This rack mount power strip provides 10 NEMA 5-15 outlets (15A) and features a 6ft long cord to conveniently plug in devices, keeping the mounting more easily and flexible
- Universal 19-Inch Rack Compatibility: Compatible with all 19-inch server racks 4 inches or deeper, this horizontal-mount power distribution unit fits many network racks and has an integrated 6ft/1.8m power cord
- Fireproof Heavy-Duty Construction: This server rack mountable power distribution unit features whole housing fireproofed construction that will support long-life working performance
- Built-In Circuit Breaker Protection: This rack mountable 10-outlet (AC100-240V) power strip features a built-in circuit breaker and reset switch, ensuring dependable performance of your power equipment and safety for using power
- Industrial-Grade Materials and Design: Features industrial equipment pure copper wire material for high power capacity, industrial-grade metal housing, and cord retention tray for enhanced durability
Form factors: horizontal and vertical mounting
Rack PDUs come in two main mounting styles, and the choice affects how much rack space the unit consumes and how easily you can reach cords and outlets.
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| Form factor | Mounting position | Rack space | Trade-off |
|---|---|---|---|
| Horizontal 1U or 2U | Mounted in a rack unit across the rack, usually in a rack-mounted shelf position. | Uses 1U or 2U of horizontal space. | Takes space that could hold equipment, but outlets are easy to see and reach. |
| Vertical 0U | Mounted along the side or rear rails. | Uses no horizontal rack units, according to Eaton’s guide. | Depends on the rack having free vertical mounting positions; exact dimensions and clearances are model-specific and not stated in general vendor guidance. |
How to choose a PDU
- Match the input. Confirm voltage, current, phase, and inlet plug against the upstream source. Eaton notes that rack PDUs come in different voltage environments and plug and outlet configurations.
- Compare connected load to ratings. Add up the real draw of the equipment, then check it against the PDU rating and the circuit it plugs into. Leave margin for the devices you expect to add.
- Match outlets and cord reach. Check outlet type, count, and spacing against the equipment’s power cords, and confirm the input cord reaches the source from the planned rack position.
- Choose the mounting form. Decide between horizontal 1U or 2U and vertical 0U, and confirm the rack has the mounting space and clearance the unit requires.
- Add monitoring or switching only when you need it. Basic distribution may be enough for simple setups. Metering helps when you need to track load, and switched units add remote outlet control with the network and access requirements described above.
- Follow the model’s installation documentation. Electrical requirements vary by model and market. Dell’s power distribution units page also stresses checking capacity and selection factors before purchase. For installations that involve the building’s electrical service, use a qualified electrician.
Special configurations
Automatic transfer switch PDUs
An ATS PDU is designed for equipment that has only one power cord. When the primary source fails or becomes unstable, the unit transfers the load to a secondary source. This gives single-corded hardware a second path, but it does not make the equipment redundant in the way a dual-corded server with two independent feeds is, and it does not replace a properly designed UPS arrangement.
Rank #3
- PDU Rack Mount Power Strip: Swivelling and stowable mounting tabs are designed to be compatible with all 19-inch server racks; suitable for racks, garages, workshops, offices, cabinets, workbenches, walls, and many other scenarios. With 6ft power cord.
- Metal Mountable Power Strip: This rackmount power strip has 8 outlets and 8 individual lighted switches for when you need to use more devices, allowing you to turn off unneeded devices individually without turning them all off.
- 1U Surge Protector: Featuring a built-in circuit breaker and reset switch, the 1200 Joule Surge Protector automatically cuts off power to protect connected equipment when voltage surges are too great, ensuring reliable performance for your network equipment.
- High Quality Build: Excellent design, exquisite workmanship, metal shell, sturdy and durable. Conforms to safety standards, you can use it with peace of mind.
- If you have any questions or problems, feel free to contact us, we will give you a satisfactory answer in time.
Hot-swappable PDUs
Eaton describes hot-swappable PDUs as units with dual AC inputs and manual transfer. The purpose is maintenance: a compatible UPS can be serviced or replaced while connected equipment keeps running. Because the transfer is manual and compatibility is model-specific, confirm the exact product pairing and follow the installation instructions before relying on it.
Quick Recap
Rank #4
- 100-125V/15A Basic Power Distribution Unit (PDU) delivers AC power to data centers, network closets, and other electrically demanding applications
- OUTPUT: 10 Rear NEMA 5-15R Outlets; INPUT: NEMA 5-15P straight plug with 15 ft power cord
- VERSATILE RACKMOUNT OPTIONS: Allows for the PDU to be installed vertically or horizontally
- ADDITIONAL FEATURES: Network-grade plugs and outlets, durable metal housing, and cord retention tray
- 3-YEAR LIMITED WARRANTY (This unit does not provide surge suppression)
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