PDU Outlet Standards
PDU outlet standards decide how many servers a rack can feed — get C13/C19 ratings and regional plug variants right before ordering.
Outlet Ratings by Connector
| Parameter | Value |
|---|---|
| IEC C13 (cold condition) | 10 A / 250 V |
| IEC C19 (cold condition) | 16 A / 250 V |
| IEC C21 (hot condition) | 16 A / 250 V |
| NEMA 5-15R | 15 A / 125 V |
| NEMA 5-20R | 20 A / 125 V |
| Schuko CEE 7/3 | 16 A / 250 V |
| BS1363 (UK) | 13 A / 230 V |
| IEC C14 inlet | 10 A / 250 V |
| IEC C20 inlet | 16 A / 250 V |
| PRO4X class PDU outlet mix | 24xC13 with 24xC19, 11-22 kW |
UL 62368-1 vs IEC 62368-1
UL 62368-1 is the US adoption of IEC 62368-1, the safety standard governing IT and power distribution equipment. For rack PDUs, the standard drives connector selection, creepage distances, clearance, and touch-current limits under single-fault conditions. A PDU listed to UL 62368-1 satisfies US authority having jurisdiction requirements; IEC 62368-1 is the common baseline for CE-marked equipment across Europe and Asia. Buyers should verify the certificate covers the exact SKU, not a family model.
EU-bound PDUs also require EMC testing under the EN 61000 series; a typical declaration includes emissions and immunity results for the full outlet configuration. This matters because the 3200 W HPE M-CRPS Titanium power supply, qualified to 80 PLUS Titanium at 96% efficiency, is itself certified under 62368-1 — and the PDU feeding it must carry the same level of evidence to pass a colocation vendor review.
Regional Plug Checkpoints
- North America: 120V 20A NEMA 5-20R circuits are needed above 1.76 kW; verify the input plug matches.
- Europe: Schuko CEE 7/3 outlets provide 16A at 230V — a 3.68 kW ceiling for single-phase plug-in PDUs.
- UK: BS1363 13A fused plugs should be derated to 10A continuous for server loads to avoid nuisance trips.
- High-density racks: 24xC13 with 24xC19 layouts on 11-22 kW PDUs handle mixed loads without rework.
Reading the Connector Cutaway
The cutaway shows the three key IEC connectors used on high-density rack PDUs: C13 for 10 A per outlet, C19 for 16 A per outlet, and C21 for 16 A in hot environments. The most visible difference is the rectangular C19/C21 profile versus the rounded C13; less obvious are the increased contact surface and insulation spacing that let the 16 A family carry higher current without exceeding temperature rise limits. C19 and C21 are identical in interface shape, but C21 is specified for higher ambient-temperature operation.
The IEC 60320 family defines C13/C19/C21 on the equipment side; matching inlets on the PDU are C14 and C20. When a rack grows beyond 120 kW, liquid cooling becomes mandatory, and outlet temperature ratings shift from cold to hot condition — which is exactly where C21 outperforms C19. Always check the inlet keyway and orientation before quoting the PDU to avoid a mechanical mismatch at deployment.
- C13: 10 A, 250 V, used on 1U and 2U servers and 10 A PDU branches.
- C19: 16 A, 250 V, standard for larger rectifiers and high-wattage server PSUs.
- C21: 16 A, 250 V, rated for elevated ambient temperature (hot condition).
- C20 inlet: 16 A, 250 V, used on the PDU input for corded or hard-wired installations.
Send Us the Outlet Matrix
Send us your outlet matrix and load table — our Shenzhen engineers will match connectors, input plugs, and regional compliance before you commit to a PDU order.
