| # | Concept | Culture | Statement | Freq. |
|---|---|---|---|---|
| 1 | preferred electrical frequency | North America | Standard electrical frequency is 60Hz | 1 |
| 2 | preferred electrical frequency | North America | Electric clocks and some appliances are optimized for 60Hz | 1 |
| 3 | preferred electrical frequency | North America | Historically adapted to 60Hz due to early influence of American electrical systems | 1 |