PDU Buying Guide | Eaton - Tripp Lite

25 Aug.,2025

 

PDU Buying Guide | Eaton - Tripp Lite

How to Choose a PDU for Your Network or Data Center

These are the top 6 factors to consider in your buying decision:

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1. Horizontal vs. Vertical Installation

PDUs can be mounted horizontally or vertically inside or outside the rack enclosure:


Horizontal PDUs are installed in the rack and take up one or two rack spaces (1U-2U). Because of their smaller size, horizontal PDUs have fewer outlets.


Vertical PDUs can be mounted on the back or side of the rack enclosure. Deep racks will often leave space for vertical PDUs to be mounted inside the enclosure. Vertical PDUs can have up to 40 outlets.

What is a 0U PDU?
A vertical PDU is also known as a 0U or “zero U” PDU because it takes up no units of rack space. As the name implies, a vertical PDU mounts to the vertical posts in a rack. Standard 19-inch horizontal PDUs can be mounted vertically outside of the rack if extra space is needed for IT equipment.

What is the best PDU for a 42U rack?
A 42U rack is the most common size of floor-standing server rack. Selecting a PDU for a rack of this size depends on how many devices you plan on installing and the devices' power requirements. If your rack will house densely packed 1U servers, make sure you choose a PDU with ample outlet receptacles, plus some open outlets for future growth. Vertically mounted PDUs are available with up to 48 outlets.

2. Voltage of Your Connected Equipment

In North America, the voltage used to power servers and networking equipment is typically 120V or 208/240V.

Europe and Asia typically provide 230V power.

Be sure that the PDU input plug matches the receptacles of your input power source.

3. Outlet Types

The PDUs outlets should match the plugs on the equipment you'll be connecting. Some PDUs offer a mix of outlet types.

Common PDU Outlet Types
NEMA 5-15R NEMA 5-20R IEC-320-C13 IEC-320-C19 NEMA L5-20R NEMA L5-30R NEMA L6-20R NEMA L6-30R

4. Number of Outlets

Select a PDU with more outlets than the number you need to ensure room for future rack growth.

5. Maximum Output Capacity

The total power required by equipment connected to the PDU must not exceed the PDU's maximum load rating (expressed in kVA). In North America, the maximum input and output capacity is limited to 80% (this is referred to as “agency de-rating”). For example, a single-phase PDU with a nominal voltage of 120V and de-rated input current of 12A (80% of 15A), has a load capacity of 1.44 kVA (120V x 12A).

6. Special Features

Remote management software – Eaton's PowerAlert® Device Manager (PADM) is the firmware that enables remote management of PDUs equipped with an LX network interface card. The latest version, PowerAlert Device Manager 20.0 (also known as PADM20), provides customizable and intuitive remote management capabilities, expanded maintenance functions and backup and restoration of device configurations. Learn more about PowerAlert.

Automatic device reboots - Eaton PDUs equipped with an LX network interface card include an Auto-Probe feature that automatically detects and fixes network connectivity problems, helping you avoid costly truck rolls for simple reboots. For example, a PDU can be configured to ping a router over the network. If the router fails to respond, the PDU with automatically power cycle the router. Learn more about Auto-Probe.

Environmental monitoring - A monitored or switched PDU's network interface can be used to receive information from environmental sensors connected to the PDU. The sensors monitor ambient temperature and humidity, as well as contact closure status of alarm, security and telecom products. See Eaton's environmental sensor accessories.

What is the best PDU for an A/V rack?
The best PDU for A/V applications depends on the specific application and setup. For a typical single-location application, such as a conference room that is not in use 24/7, does not require networking and is powered off when not in use, a basic rack-mount PDU like Eaton's PDU will be suitable.

A more complicated A/V system, such as a multi-room system, a digital signage system or a control center, will involve more components and increased demands. Such a system is likely to be operational 24/7/365, will need devices to be monitored and rebooted remotely and will require secured access. An ideal PDU in this case is Eaton's switched PDU model PDUMH15NET.

Frequently Asked Questions

What is the difference between a UPS and a PDU?
An Uninterruptible Power Supply (UPS) provides battery backup to IT equipment and other electronics during power outages. A UPS also filters incoming power and provides surge protection.

A Power Distribution Unit (PDU) distributes the power from the UPS or other AC source, such as a wall outlet or generator, to multiple devices. It does not generate or condition power on its own.

What is the best power supply for a rack?
A Power Distribution Unit (PDU) is designed for the specific purpose of powering multiple devices in a server rack or enclosure. A PDU distributes the available amperage evenly and efficiently among all outlets so that all connected servers, networking hardware, telecom equipment and other devices receive the best available power to maintain operation. PDUs are available in a variety of styles that provide everything from basic power distribution to enhanced remote power management.

What is the difference between a PDU and a rack-mount power strip or surge protector?
PDUs, power strips and surge protectors all provide multiple outlets. What a PDU adds is support for robust distribution of reliable network power for multiple servers, networking hardware, telecom equipment and other IT devices. A PDU will distribute the available amperage evenly and efficiently among all outlets so that all connected equipment receives the best available power to maintain operation. PDUs can also provide higher maximum load capacities than power strips. Basic 120V PDUs are available from Eaton that can provide up to 3.8kW of power, much more than even the typical industrial power strip can handle.

Depending the type of PDU, you also get options for input current monitoring, remote monitoring and control, secure access and environmental monitoring.

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Note that most PDUs do not provide surge protection because a PDU installed in a rack is typically connected to a UPS system. The UPS protects connected equipment from power surges and line noise interference. For Eaton PDUs with premium Isobar® surge protection built in, see our selection.

What is the difference between a power distribution unit and a power distribution center or cabinet?
A power distribution cabinet, also known as a power distribution center, is electrical equipment that provides supply and redistribution of electrical energy, protection of electrical power lines and protection of the overload and short circuit currents. See Eaton solutions for power distribution centers.

How do you use a hot-swap PDU?
The dual input and manual bypass features of the PDU enable UPS system maintenance–from battery replacement to complete power module exchange–without powering down connected mission-critical equipment and hiring costly service specialists. Here are the basics of using a hot-swap PDU:

  1. Plug the primary input of the hot-swap PDU into an on-line UPS system.
  2. Plug the secondary input into utility power, i.e. a wall outlet.
  3. If the UPS needs to be taken offline for maintenance, repair or replacement, use the manual transfer switch to move the connected load to the secondary input. When the UPS is restored, switch the PDU back to the primary input.

For further reading, refer to our hot-swap technology page.

How does a PDU help monitor conditions in the rack, network closet or data center?
A monitored or switched PDU has a network interface that can be used to receive information communicated from environmental sensors connected to the PDU, helping personnel ensure optimum operating conditions. The sensors monitor ambient temperature and humidity, as well as contact closure status of alarm, security and telecom products.

Learn more about Eaton's solutions for environmental monitoring.

Must-have accessories: PDU power cords
Each device you plug in must have at least one power cord connecting it to the PDU. You could use the cord that came with the device, but consider these options that help you manage your devices more efficiently:

  • Color-coded power cords – Look inside the average data center rack and you'll likely see a confusing array of gray or black cords. By color-coding the power cords running to different types of equipment, the right cord is easy to identify at a glance and will help prevent accidental disconnection of the wrong device. Eaton offers an array of PDU cords in blue, green, orange, red, white and yellow – along with gray and black, of course. See the selection.
  • Cords of different lengths – Devices mounted close to the PDU need only a short cord. Those mounted furthest from the PDU may require a cord that is several feet long. Using the appropriate-length cord helps reduce cable clutter and promotes more efficient airflow and cooling within the rack. See Eaton's full selection of power cords.
  • Plug-lock inserts – Help prevent accidental disconnection of critical equipment. Plug-lock inserts strengthen the physical connection of the cord and outlet and provide a no-clutter alternative to zip-tie cords or electrical tape. See plug-lock inserts now.
  • Power cord adapters – If you find you need different types of receptacles than your PDU provides, power cord plug adapters are a simple and inexpensive solution that enables you to keep using your existing PDU. Find an adapter cord now.

A Complete Guide to DIN Rail Terminal Blocks - RS Components

What exactly are terminal blocks? These insulated attachments protect electrical equipment, preventing short circuits and excess current from surging across connecting wires.

They are clipped onto DIN rails - globally standardised metal rails used to mount electrical relays, circuit breakers and similar equipment in racks, control cabinets and enclosures. DIN rails are specifically made to provide a location for control devices. In addition to terminal blocks, these might include actuators (to switch devices on), power supply units, and circuit breakers.

DIN rail terminal blocks are made from plastic or other insulating materials. They provide a safe interface between different components on and sections of the DIN rail.

DIN is an acronym for Deutsche Institut für Normung, the German Institute for Standardisation. Rack mounts - cabinets used to house industrial, communications and computer equipment - were first devised in Germany in the s and the resulting standards were then globally adopted from the s onwards.

Terminal blocks are also known as terminal strips or connection blocks.

DIN rail terminal blocks are available with a variety of specifications for different uses. Their compact size gives them a significant degree of versatility; they can be deployed even when space is limited. However, for truly small-scale work, look for miniature and even micro-miniature variations.

Some models feature one or more fuses in a special hinged section for additional protection against overcurrent, making them a good choice for use with sensitive equipment like sensors and relays. Fuses are standard components that protect against electrical surges with a component that melts when exposed to excess current, breaking the circuit. These models often feature an LED to indicate when the fuse has blown. You may see such models referred to as DIN rail fuse holder terminal blocks.

Varying current ratings are indicated by colour coding on some models.

DIN rail terminal blocks are also distinguished by their levels. A single-level model has a single wire connection - also known as a single feed through. By contrast, a dual-level model has two connections - one above the other. The second set of wiring effectively functions as a second terminal block, in more or less the same space as a single feed model. These are sometimes referred to as double density terminal blocks.

Triple and quadruple level models are also available, along with high-end eight and 16-level options.

Termination type is another frequently used classification method. Screw terminal blocks are a common, general-purpose model. These use a clamp to secure wiring, where a screw is inserted to tighten this, pressing the wire into place. In some models, the clamp is spring-loaded, providing a more secure connection resistant to vibration.

Ring terminal blocks can be deployed more quickly because they feature preinstalled nuts that are ready to be tightened without removal first. These are also known as plug-in or push-in terminals because the wires can simply be pushed into the connection gaps.

Typically smaller than standard DIN rail terminal blocks, ring terminal blocks save space. They are usually four-level models, meaning that four wires can be connected through the block.

Earth terminal blocks are a third type. Also known as ground terminal blocks, these are used with wiring that requires direct earthing (connecting to the ground to discharge excess electrical charge). They typically feature green and yellow housing and can be mounted onto DIN rails, with the wiring secured via screws or clamps.

For more information, please visit European standard switch.