Transfer switches are sized based on what criterion?

Transfer switches are sized primarily based on the calculated continuous current that they will be required to handle. This criterion ensures that the transfer switch is capable of safely and reliably managing the electrical load under normal operating conditions without overheating or failing.

Sizing a transfer switch according to continuous current entails assessing the maximum demand of the connected loads, ensuring that the switch can handle this load consistently over time. This is crucial in applications where power sources are switched frequently, as it maintains system integrity and safety.

Considering the other options, while estimating maximum load and peak load observations are relevant for understanding the potential demands placed on electrical systems, they are not as critical as the continuous current when it comes to sizing equipment for reliable operation. Similarly, the voltage of the devices being powered, while essential for compatibility, does not directly influence the size of the transfer switch itself, which is more concerned with current capacity. Thus, the selection based on calculated continuous current is the most accurate and applicable criterion for sizing transfer switches.