IEC 60320 connectors: the power cord reference for buyers

IEC 60320 is the standard that names the ends of a power cord. It is the reason a server cord is called a C13 and a blade chassis cord is called a C19, and it is why a cord ordered by photograph instead of by code arrives in the wrong temperature class. The standard itself is dry — IEC 60320-1:2021, Edition 4.0, Appliance couplers for household and similar general purposes — but the buying decision it drives is not. This is the full connector reference, the ratings on both sides of the Atlantic, and the two places where the chart alone will mislead you.

What the standard actually covers

IEC 60320 covers the appliance coupler: the detachable joint between a cord and a piece of equipment. It does not cover the wall plug. That end belongs to the destination country — NEMA in North America, BS 1363 in the UK, and so on — which is why a cordset always carries two identities, one at each end.

The numbering is simpler than it looks, and getting it right removes most of the confusion in a quote:

• Odd numbers are connectors. These live on the cord and are female. C13, C15, C19.
• Even numbers are inlets. These are mounted on the equipment and are male. C14, C16, C20.

So a C13 connector mates with a C14 inlet. The pairs are always odd-then-next-even: C13/C14, C15/C16, C19/C20. When someone asks for a “C14 cord,” they usually mean a cord that fits a C14 inlet — which is a cord terminated in a C13. Confirming that in writing before tooling a run costs nothing and saves a rebuild.

One consequence of the naming trips up almost every first rack order. A rack PDU presents C13 outlets, so a jumper from the PDU to a server needs a C14 plug at the PDU end and a C13 connector at the server end. That is the cord sold as a C13-to-C14 jumper, and it is the highest-volume cord in any data centre.

The full IEC 60320 reference

Below is every coupler pair in general use, with both ratings. Note the second column — it is the one most reference charts omit.

IEC and North American ratings per the StayOnline IEC 60320 reference chart, cross-checked against IEC 60320-1:2021. Verified 17 August 2026. Always confirm the rating printed on the specific listed part.

The two-column split is not a rounding difference. IEC rates C13/C14 at 10 A; UL and CSA list the same coupler at 15 A. Both are correct within their own approval system, and the one that governs your order is the one for the market you ship to. A European engineer specifying to 10 A and a US buyer quoting 15 A can be describing the identical part and still fail to agree on a spec sheet.

Temperature class: the C13 and C15 trap

The C-number does not only set a current. It sets a temperature condition at the pins, and this is where an otherwise careful order goes wrong.

Temperature conditions per Interpower. Verified 17 August 2026.

A C13 and a C15 carry the same current and look nearly the same in a listing photo. The C15 has a notch, and the matching C16 inlet carries a key opposite the earth pin. That key does one job: it prevents a cold-condition connector from being pushed into a hot-condition inlet. Equipment that runs hot cannot be fitted with a cord that is not rated for the heat.

The keying runs one way only. A C15 connector fits a C16 inlet and a standard C14 inlet, so a C15 cord is backwards compatible with ordinary C14 equipment. A C13 will not enter a C16 at all. For a mixed rack, that asymmetry is useful: the C15 is the cord that fits everywhere, and standardising on it removes a category of field error at a small premium per unit.

The connector is a ceiling, not a promise

Here is the part a reference chart cannot tell you: the coupler rating is the ceiling of the assembly, not a description of it. What the cord actually carries is decided by the cordage — the gauge, and the jacket type printed along it.

Ampacity for flexible cord is set by NEC Table 400.5. An 18 AWG cord uses measurably less copper than a 16 AWG one and costs less to build; on a low-draw device that is a legitimate saving, and on a dense rack it is a heat problem wearing a correct-looking C13 on the end. The connector code stays the same either way.

The assembly is also only as hot-rated as its weakest layer. A 120 °C C15 connector on cordage rated for less does not give you a 120 °C cordset — it gives you a mismatch that will pass a visual inspection and fail on a hot day in a closed cabinet.

We have measured what that looks like. In our own bench study of seven retail C13 cords, every sample carried honest copper for its printed gauge — 1,587 to 2,724 circular mils, 98 % to 115 % of nominal. But under a ten-minute heat soak at roughly 12.5 A, 2 of the 7 ran hotter at the moulded plug than anywhere on the cord itself, peaking at 48.5 °C and 46.5 °C. Heat concentrating in a moulded joint rather than along the conductor is an assembly signature, not a copper one — and no connector code on a datasheet would have predicted it.

Specifying a cordset without a drawing

Most buyers do not arrive with a drawing, and they do not need one. Six lines are enough for a power cord manufacturer to quote a build rather than pull stock:

If you can state the load in amps and the two ends, a manufacturer can work back to the rest. That is the difference between a custom power cord built to a spec and a stock cord that happens to be close: the first is quoted from those six lines, the second is quoted from what is in the warehouse. For bulk power cords on a repeating SKU, the same six lines become the part number, and the only remaining variables are carton marking and lead time.

Origin belongs on that list now rather than in a footnote. Two mechanically identical C13 cords can land at different costs depending on where they were actually built, and that difference only holds up if the origin is real and documented per unit — see how to verify a Vietnam country of origin for what that evidence looks like at entry.

Getting the cord right

The C-number is a good shorthand and a poor specification. It fixes the current ceiling, the temperature class, and the mechanical fit — genuinely useful, and enough to stop a C13 from being pushed into a C16. It says nothing about the copper, the jacket, the moulded joint where the heat actually collects, or the country the cord came from. Read the coupler code and the cordage legend together, state your load rather than guessing a gauge, and treat the temperature class as a property of the whole assembly.

Kestner builds IEC cordsets on its own lines, C13/C14 through C19/C20, with the vetting checklist we would want applied to us as the standard. If you have the coupler codes and the load, send them over and we will quote the cord built to them.