To quote from “blogquail.com”
When it comes to understanding the rating of a power cord, there are a handful of factors to consider directly related to the amperage and voltage of the cord. Each element of a power cord has a maximum rating as an individual component. The elements are the plug, the wire, and the connector. The overall rating of a power cord is effectively the weakest link out of these ratings. Here, we take our US power cord as an example:
- The plug is the NEMA 5-15P, which is explained in detail and rated at 15A/125V
- The wire is 18/3 SVT – 10A/300V and is explained in greater detail
- And at the other end is the IEC-60320-C13 connector, rated at 15A/125V.
So the overall rating of the power cord is effectively the lowest rated component out of these three elements, which for our example is 10A/125V.
| American Wire Gauge | Amp Rating |
| 18 | 10A |
| 16 | 13A |
| 14 | 16A |
| 12 | 20A |
| 10 | 30A |
There are certain differences between US ratings and international ratings. The international IEC rating is a designation given to connectors used in appliances and computers/laptops. IEC connectors have different ratings depending on the region. Let’s take the C13 for example. In the USA, this plug is recognized as up to 15A, and internationally up to 10A. Another IEC connection- the C19, is rated in the USA as 20A and internationally at 16A. We can tell the rating of a plug by whether it’s a US cord or international.
So how do you choose the cord that’s right for you? First, you’ll want to know the maximum power for your appliance or device, and then choose the connecting plugs accordingly. From there, you’ll find the rating that correlates to your needs.
Example: My device draws 12A, it plugs into a standard US outlet, so it will need an NEMA 5-15P > 15A. The inlet on my device is an IEC-60320-C14, therefore, I will need a C13 connection on the cord. Since my device needs 12A, I will need a wire gauge to handle this amperage. It would be 16AWG.
My final configuration would be NEMA 5-15P Plug—16/3 Wire—IEC-60320-C13 Connector.
