Data Center PDU Guide: Power Distribution for Server Racks
A server rack is only as reliable as the power that feeds it. The PDU (Power Distribution Unit) is the vertical power strip inside the rack that takes the feed from the floor and distributes it to every server, switch, and storage device. Choosing the right PDU — and the right cords to feed it — is a reliability decision, not a cosmetic one. This guide explains how PDUs work, the main types, and how to match cords and connectors to your rack.
What a PDU does
A PDU takes one or more power inputs and distributes them to multiple outlets in a rack. In a data center the PDU is the single point between the facility power and every piece of IT equipment, so it must handle sustained load, allow for redundancy, and be serviceable. The two things that define a PDU are its input rating (how much power it can accept) and its outlet layout (what plugs the equipment uses).
Input: single vs dual feed
| Input | What it means | Use case |
|---|---|---|
| Single feed | One power source to one PDU | Edge racks, non-critical loads |
| Dual feed (A/B) | Two independent sources feed two PDUs or a dual-feed PDU | Critical racks, always-on servers |
| Split-phase / three-phase | Higher total power, balanced across phases | Dense racks, large loads |
For critical equipment, dual feed (A and B circuits) is the standard: each server has two power supplies, one fed by each PDU, so a single failure does not take the server down. If your rack is single-fed, at least plan for it — retrofitting dual feed is expensive.
Outlets: the connectors your equipment actually needs
The PDU outlets must match the equipment inlets. The dominant family in racks is the IEC 60320 C series — see our IEC C13 / C14 / C15 guide for the pinout and amperage differences.
- C14 / C16 outlets — the standard rack outlets; take C13 and C15 plugs respectively.
- Locking (latching) outlets — the same C14/C16 face with a latch, so a cord cannot be accidentally pulled out. Recommended for critical equipment because vibration and cable management in a dense rack cause accidental disconnects.
- High-current outlets — 15 A / 20 A for loads that exceed the standard 10 A / 15 A.
For the cords themselves, match the gauge to the load and keep a consistent length (usually 2 m) so the rack is clean and current is evenly distributed. Do not daisy-chain extension cords through a PDU — feed equipment directly from the outlet. See the gauge guide for the voltage-drop math on longer runs.
Smart vs basic PDUs
| Type | Capability | When to use |
|---|---|---|
| Basic (dumb) | Outlets only, no monitoring | Budget racks, low density |
| Metered | Reports total power / energy | Cost allocation, capacity planning |
| Switched | Remotely on/off each outlet | Rebooting devices, lab / dev racks |
| Outlet-level metering | Per-outlet power measurement | Dense racks, granular monitoring |
The level of “smart” should match the criticality of the load. A single edge rack does not need per-outlet metering; a dense production rack benefits from it.
Common PDU mistakes
- Overloading a single feed — summing the nameplate power of every device and exceeding the PDU rating.
- Mixed cord gauges — thin cords on high-current outlets, causing heating at the connection.
- Non-locking cords on critical gear — accidental disconnects that take servers offline.
- No A/B separation — feeding both power supplies from the same circuit, which defeats redundancy.
- Wrong certification for the market — a PDU or cord not listed for the installation region failing inspection.
How HENG-WELL can help
HENG-WELL supplies the full range of data center power cords — IEC C13, C14, C15, and C16, standard and locking, in the gauges and lengths racks require, matched to the certification of the destination market. We help you size the cord gauge against the PDU outlet current and keep the rack serviceable with consistent, color-coded, locking cords. Tell us your PDU configuration, load, and market, and we will specify the cord set that keeps the rack running.
HENG-WELL — power cords and connectors manufactured to global standards since 2011.
