Factory sourcing notes
How Many PDUs per Rack? An A/B Power Checklist for UAE Buyers
If you are buying rack power for a server room in the UAE, you may already have asked: how many PDUs per rack—one or two? I want to look at that question separately, because agreeing on a quantity does not always mean you are ready to order. The more useful question is what happens to the equipment you need to keep running when one supply path becomes unavailable.
For a rack of dual-supply equipment designed for A/B power redundancy, two PDUs commonly serve the two supply paths. That is not a fixed quantity for every rack. Tell the supplier how the equipment is powered and what interruption the project can accept. Then review the following points with the project’s electrical lead.
Before buying two, distinguish these arrangements
| Proposed arrangement | What it provides | What still needs checking |
|---|---|---|
| One PDU on one supply path | Power distribution within the rack | Can the project accept an interruption of that path? |
| Two PDUs on the same upstream supply | More outlets and distribution positions | A shared upstream fault may still disconnect both. |
| Two PDUs on separately designed A/B paths | Two supply paths for dual-supply equipment | Does the equipment support this arrangement, and can either path carry the required surviving load? |
Eaton’s selection guidance considers redundant equipment power supplies, PDUs and upstream supplies together. “Two PDUs for redundancy” is therefore an incomplete purchase specification. The UAE is the installation destination; the actual power architecture still needs confirmation against the project drawings.
Half the load in normal operation is not the whole calculation
Ask the electrical lead to add two columns to the load schedule: “A path only” and “B path only.” Belden’s explanation of dual feeds highlights the need to consider the load carried by the remaining path, rather than just the readings while both paths are available.
Assume the engineer has confirmed 8 kW of usable capacity on each path and a required surviving load of 6 kW. Also assume the equipment shares load equally in normal operation and can transfer the full load to the remaining path.
Normal equal sharing: 3 ÷ 8 = 37.5% per path.
One path available: 6 ÷ 8 = 75%.
The 8 kW figure is an assumed, confirmed usable capacity—not an Eagle King product rating. These are not market percentages or an electrical design. A real project also needs checks on current, power factor, phase or branch allocation, protection settings and equipment behaviour during a supply change.
Send this sheet to both the supplier and the project engineer
| Check | Information to provide |
|---|---|
| Upstream paths | A source: ____; B source: ____; person reviewing common failure points: ____ |
| Rack equipment | Equipment and power-supply list: ____; dual or single supply: ____ |
| Load conditions | Normal: ____; A only: ____; B only: ____; calculation basis and required headroom: ____ |
| Limits along the path | Applicable limits for upstream equipment, protection, PDU, branches, outlets and cables: ____ |
| Acceptance records | Drawing revision: ____; load schedule revision: ____; model and cabling record: ____; acceptance owner: ____ |
I have spent 23 years in sockets and electrical accessories, including 10 years in foreign trade, and I have also worked as a buyer. When comparing quotations, I first check whether both suppliers are quoting against the same requirements. At Eagle King in Cixi, our in-house laboratory can support sample assessment and test preparation. The checks on the PDU itself and acceptance of the complete server-room power system should be specified separately.
Two other purchasing questions
Should single-supply equipment be listed separately?
Yes. Identify it so the electrical lead can assess an acceptable interruption or a suitable transfer arrangement for that equipment. An A/B rack does not automatically give a single-supply device a redundant connection.
Does this checklist demonstrate a data-centre Tier rating?
No. It clarifies purchasing inputs; it does not replace the complete facility design, testing or certification.
If you are still collecting basic details such as input connectors and mounting positions, use our Middle East rack PDU RFQ checklist alongside this sheet. Send the confirmed equipment list and requirements through our website’s WhatsApp. Mark the open questions too, so we can identify the information still needed.