If you live in the U.S., you’re almost definitely familiar with the holes in the prongs of electrical plugs. Many ... theory is that the holes save metal, which helps cut costs over time.

That design ensures only 20-amp rated plugs can ... (NEMA), the holes are technically optional and mainly for manufacturing purposes. The holes let machines hold the metal blades in place while ...

The US uses two standard electrical plug types: Plug Type A and Plug Type B. Both have two parallel pins for power, while the latter has an additional grounding pin for safety. But if you look ...