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Browse the Lanz IEC connector range and you may find two parts from the same family with different current ratings. One IEC 320 C13 plug is rated 10 A at 250 V AC, while a C14 plug connector is rated 15 A at 250 V. Both use flame-retardant nylon housings and nickel-plated brass contacts, and both belong to the IEC 60320 family.
The different ampere ratings do not necessarily mean that one connector is simply "stronger" than the other. Current ratings are tied to the standard, certification system, test conditions, and market in which the value is declared.
That matters when comparing parts from different suppliers. A current rating is not a fixed physical dimension like pin spacing or body size. It is a declared electrical limit based on a specific set of test conditions, and those conditions need to be understood before two ratings can be compared directly.
Current Rating Is Defined by Temperature Rise
IEC 60320-1 assigns nominal current ratings to appliance couplers, including 2.5 A, 6 A, 10 A, and 16 A. Those values are not based on conductor size alone. They are tied to how the connector performs under a defined electrical and thermal test.
For the temperature-rise test, the connector is operated at 125% of its rated current for one hour. A 10 A connector, for example, is tested at 12.5 A. The test is carried out under controlled ambient conditions, and the temperature rise at the terminals is measured against the limits set by the standard. Contact performance is also checked under the required switching and breaking conditions.
That context matters in real equipment. The published rating assumes a defined test setup and ambient temperature. A connector installed next to several other loaded inlets, enclosed in a warm cabinet, or exposed to poor airflow may run hotter than it did during certification testing.
The current rating is therefore a standardized reference point, not a guarantee that the connector will behave the same way in every installation.
One connector, two standards, two numbers
The same C13 geometry is rated 15 A in the United States and Canada, where UL 498 and UL/CSA 60320-1 apply. Outside North America, most countries follow IEC 60320-1 and cap the connector at 10 A. A maker that sells into both markets publishes both numbers, and the careful ones print them on the same line.
The Lanz C19 and C20 cable connector does exactly this. The page reads 16 A, 250 V AC, then adds 20 A, 250 V AC for UL and CSA in the same breath. One part, one housing, one set of contacts, two ratings that differ by 25 percent, decided by which approval body signed the file.
A high current C19 to C20 assembly specified at 16 A can therefore ship into a North American rack and be under rated for the load the customer planned. The customer read the IEC figure. The equipment was built around the UL figure.
The Destination Market Sets the Applicable Rating
The same connector can carry different current ratings in different markets because the applicable approval system changes.
Interpower uses Brazil as a practical example. A C13 connector that may be rated 15 A for North American use is typically limited to 10 A under the IEC-based requirements used in Brazil. Replacing the NEMA plug on a North American cord set with a Brazilian rewireable plug does not transfer the 15 A rating to the connector at the other end. The finished cord also no longer retains its original approval once it has been modified.
This is why the same connector family may appear with different current limits depending on where the product is sold. A C13 may be listed at 10 A under IEC requirements and 15 A for North America, while a C19 is commonly used for 16 A applications.
For sourcing, the market matters as much as the part number. The rating on a datasheet only makes sense when it is read together with the standard and approval behind it.
Current Rating Changes as Ambient Temperature Rises
IEC current ratings are established under controlled temperature conditions. The standard temperature-rise test is performed around 25°C ambient, and the rated current applies within the operating conditions defined by the standard.
Once the ambient temperature rises beyond those conditions, allowable current may need to be reduced. IEC 60320-1 includes guidance for derating accessories used above 35°C because less thermal margin remains as the surrounding air gets hotter.
That becomes important inside real equipment. A panel inlet mounted in a closed cabinet beside a power supply, drive, or other heat-producing components may see ambient temperatures of 50°C or more. In that environment, the current that can be carried safely may be lower than the nominal rating printed on the product.
The same principle applies to power cord temperature ratings. A temperature or current figure is only useful when the conditions behind that rating are understood.
Bundling Changes the Thermal Limit
North American practice accounts for conductor grouping with adjustment factors. NEC Table 400.5(A)(2) gives the ampacity of flexible cord with no more than three current-carrying conductors at an ambient temperature of 30°C or less. When more conductors are grouped together, Table 400.5(A)(3) applies adjustment factors: 0.80 for four to six conductors, 0.70 for seven to nine, and 0.50 for ten to twenty.
The reason is heat. Several loaded cords in a chase, or multiple circuits bundled into one harness, cannot dissipate heat as easily as a single cord in free air. As the number of current-carrying conductors increases, the allowable current per conductor has to come down.
The same issue appears in a multi outlet socket module. Twelve C13 outlets may all be operating within their individual ratings, but the branch circuit still has its own limit. If each load draws 1.5 A, the total is 18 A. On a 20 A branch limited to 16 A for continuous loading, the outlets are not the problem-the total branch load is.
The Assembly Is Limited by Its Lowest-Rated Component
A 16 A inlet does not automatically make the finished cord set or appliance connection suitable for 16 A. The conductors, plug, connector, fuse, and other components all have to support the intended load.
For IEC 60227 Type 53 flexible PVC cord, conductor size places a practical limit on continuous current. Typical three-core ratings in free air increase with cross-sectional area, from 0.75 mm² through 1.0 mm², 1.5 mm², and 2.5 mm².
If a 16 A inlet is paired with cable sized for only 10 A, the assembly must be treated according to the lower limit. That is why wire gauge and cord length selection should be checked against the current requirement of the complete assembly, not just the rating printed on the connector.
Temperature ratings and overcurrent protection add two more limits. A high-temperature jacket only matters when the finished cord is actually approved and marked for that temperature. The fuse or circuit protection must also be coordinated with the weakest component in the current path. If a 16 A inlet and 1.5 mm² cord are protected by a 13 A fuse, the protected assembly is limited to 13 A.
What to Include in the Connector Specification
Specify the conditions the connector will actually see in service. Confirm whether the current rating is based on IEC, UL, or another standard, and check temperature-rise data for the expected enclosure temperature.
Also define conductor size, core count, bundling conditions, and altitude where relevant. Then compare the load against the lowest-rated component in the assembly, whether that is the connector, cable, fuse, terminal, or branch circuit.
Lanz Electronics has manufactured inlets, outlets, power cords, switches, relay sockets, and custom cable assemblies since 2006, with more than 1,000 product specifications and 100% final testing of critical parameters.
