What should drive the choice?
Choose the outlet mix from the equipment inlet inventory and complete cord ratings. Leave documented room for likely additions instead of relying on connector adapters later.
Research based on linked manufacturer documentation. We have not physically tested this equipment.
C13 and C19 describe interfaces in a larger power path
C13 and C19 often appear in rack PDU specifications, but buying the correct PDU requires more than choosing the larger-looking connector. First identify the inlet on each power supply, the available PDU outlet, the cord needed between them and the voltage delivered by that PDU. These are separate fields. A matching physical interface is one compatibility check, not a complete power specification.
Eaton’s connector chart identifies C13 and C19 as the female interfaces and C14 and C20 as the corresponding male interfaces. In common rack use, a C14-to-C13 cord connects a C13 PDU outlet to equipment with a C14 inlet; a C20-to-C19 cord serves the corresponding C19 outlet and C20 inlet arrangement. See the manufacturer’s inlet and receptacle chart and Eaton’s rack power cord explanation.
Use these names on the order and in the asset record. Terms such as server cord or IEC lead are too broad to establish compatibility. Include both ends, the assembly rating and length. If a supplier provides an equivalent cord, compare those recorded fields before treating it as an acceptable substitute.
Count power supplies rather than only devices
An equipment count can understate outlet demand. A server with two power supplies usually needs two cords in the planned arrangement, while a management appliance with an external power supply may use another connector altogether. Inventory each supply individually. Record which ones are fitted today and which additional supplies are included in the approved expansion plan.
For an illustrative rack, suppose there are six servers with two C14 inlets each, a storage appliance with two C20 inlets, two switches with one C14 inlet each and a management device with one C14 inlet. That creates demand for fifteen C13 outlet connections and two C19 connections before spares. These are invented inventory counts for planning practice, not a configuration claimed for particular products.
If those dual-supply systems belong on separate A and B paths, split the inventory by path before choosing a PDU. In this example each path may need six server connections and one storage connection, with the single-supply devices assigned according to their approved availability plan. A PDU with enough outlets in total may still be the wrong choice for either individual path.
| Recorded field | C13/C14 path example | C19/C20 path example |
|---|---|---|
| Equipment inlet | C14 on the equipment power supply | C20 on the equipment power supply |
| PDU outlet | C13 | C19 |
| Typical matching cord ends | C14 male to C13 female | C20 male to C19 female |
| Remaining checks | Assembly rating, voltage, length and equipment approval | Assembly rating, voltage, length and equipment approval |
Read the assembly rating and regional approval
Avoid declaring one universal usable current from the connector name alone. Regional approvals, the receptacle, the equipment inlet and the complete cord assembly can carry different limits. The PDU may also impose bank and total limits. A buyer needs the applicable ratings for the actual installation, rather than a single number remembered from a connector chart.
Eaton’s Rack PDU G4 cord table illustrates this directly: it lists C14-to-C13 assemblies with different current ratings, including 10A and 15A examples, and separately lists C20-to-C19 assemblies. The ends alone therefore do not fully specify a cord. The manufacturer’s cord selection table provides model-specific examples to check against the equipment requirement.
A larger connector does not increase the capacity of the upstream PDU or branch supply. Nor does a higher rated cord authorize drawing more current from a lower rated outlet. Keep all these constraints in the worksheet. When they differ, the relevant lower limit constrains that path, while the equipment’s approved supply requirement still has to be satisfied.
A familiar IEC connector does not identify the delivered voltage
A rack may use visually similar IEC interfaces in different voltage arrangements. Confirm the actual output voltage and the equipment power supply’s accepted input range. Read the power supply label or manufacturer documentation for the fitted supply, because a chassis family can have more than one option. Do not infer electrical compatibility from a C14 or C20 inlet alone.
Consider a hypothetical replacement server whose documented supply supports the rack’s existing voltage and uses C20 inlets. Its arrival changes the outlet and cord requirements even if the rack’s voltage remains unchanged. Conversely, moving an existing server to a different-voltage PDU requires a new compatibility check even if the old cord physically fits. These are different changes and should have different approval evidence.
The cord’s voltage rating describes its permitted use; it does not transform the source voltage. If the rack is part of a voltage migration, review the source, UPS output, PDU, cords and every attached supply together. Resolve equipment that does not support the new arrangement before ordering a replacement PDU around the majority that does.
Outlet position and cord length are purchasing requirements
A count of twenty-four C13 outlets says little about whether those outlets are accessible after installation. Compare the PDU orientation, outlet spacing, server rail travel and rear-door clearance. Large connector bodies, right-angle exits and retention accessories can affect neighboring access. Ask for dimensioned product information when the rack is crowded rather than relying on a front-facing catalog image.
Choose cord lengths from the intended route with service movement considered. An overly short cord can restrict access; unnecessary slack can obstruct other equipment and complicate identification. There is no single ideal length for a whole rack. A small set of planned lengths is usually easier to document and stock than an unrecorded mix of whatever cords happen to be available.
Label both ends with the asset and power-supply identifier. For A and B paths, record the source relationship in addition to using a color convention. Color helps an operator follow a known scheme, but it does not demonstrate independent sources. Keep the outlet schedule current after any server replacement or PDU move so the physical installation and inventory agree.
Check how the selected locking system works
Retention features can reduce accidental disconnection during service, but compatibility needs checking at both ends. Some systems use a dedicated compatible cord or outlet; other accessories attach to an existing connection. Confirm the exact manufacturer-supported combination and how an operator releases it. A locking claim on one component does not establish retention for the entire cord path.
For equipment serviced in a dense rack, include removal and replacement access in the review. The technician should be able to identify the correct feed and operate its retention mechanism without pulling neighboring connections. Keep the required accessory part numbers with the cord inventory, particularly if a spare generic cord would not provide the intended retention.
Do not let cable appearance replace the rating review. A thick jacket, matching color or locking shell is not evidence of the assembly’s current and voltage approval. Retain the product specification for each stocked cord type. That makes future substitutions reviewable when the original packaging is long gone.
Specify the outlet mix for the likely next purchase
Return to the illustrative inventory of fifteen C13 and two C19 connections. If an approved next-stage purchase adds two dual-supply devices with C20 inlets, the aggregate demand becomes fifteen C13 and six C19 connections. A PDU bought with only two C19 outlets would need another solution even if several C13 outlets remained empty. This is an outlet-mix constraint, separate from the rack’s remaining electrical capacity.
Document realistic additions rather than buying a vague amount of future proofing. If the future equipment is unknown, ask suppliers for options with a different outlet mix or documented combination outlets, then compare cost and compatibility. A flexible outlet design still needs its own ratings and approved cord combinations checked. It does not remove the need for the inventory.
Before approving the order, reconcile outlet counts per power path, complete cord part numbers, voltage compatibility, bank limits and service access. Use the UPS sizing guide for the output capacity and runtime work that accompanies this connector plan. Select C13 and C19 distribution from the equipment requirements, and keep the worksheet so the next expansion can start from evidence.
Sources and research basis
- Eaton UPS and power management fundamentals handbook, connector chartPrimary documentation · checked 15 October 2026
- Eaton AC power cords explainedPrimary documentation · checked 15 October 2026
- Eaton Rack PDU G4 compatible power cord ratingsPrimary documentation · checked 15 October 2026
Manufacturer specifications describe the documented configuration. Buying recommendations are our interpretation of those features. No original runtime, acoustic, efficiency, switching or software test is claimed. Report a correction.