Why can some (US) outlets fit a plug from either way you put it in, but some plugs have a fatter and skinnier prong?
In: 8026
This is to ensure that the plug can go into the outlet in only one orientation.
The wider blade is for the “Neutral” wire which is actually equal to ground. The narrower blade is for the “Hot” wire, or the source of electricity. Connecting a device between Hot and Neutral allows current to flow from Hot to Neutral, powering the device.
Some devices don’t have a user-operable switch, so it doesn’t matter which way the plug goes into the outlet, and both blades on the plug will be narrow.
Devices that do have a user-operable switch generally will have blades of different width in the device’s plug. Such a plug is “polarized.” The purpose of a polarized plug is to ensure the device’s user-operable switch is always connected to the Hot wire when the device is plugged in. This makes the device a little safer to use, and less likely to harm someone if they open the device without unplugging it first (but at least have it turned off). Most of the device won’t be hot, only a small portion of the wiring inside will be Hot—that part before the switch.
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