It will work either way, there is no polarity when a circuit is made.
There is polarity before a circuit is made. One wire is live, one wire is a neutral return.
For a basic heater, plugged in one way will have the heating element always live, and the other way it will only be live when it is switched on and a circuit is made.
One wire is live in that it moves between —x and +x volts in a sine wave. The neutral is often connected to earth/ground somewhere upstream and should be 0v. So if you just pop that power into a transformer and then regulate and only use the DC then it’s completely irrelevant which way you plug it in.
However there’s plenty of cheaper ways to get a lower voltage, or to power a device from mains power that when done badly can reference what is thought to be neutral (and this ground) but could easily become live and make something metallic become live either without fault, or with fault to a minor component.
With single phase AC there is no polarity, when you plug something in you don’t need to know which plug is live, it will work either way.
It will work either way, there is no polarity when a circuit is made.
There is polarity before a circuit is made. One wire is live, one wire is a neutral return.
For a basic heater, plugged in one way will have the heating element always live, and the other way it will only be live when it is switched on and a circuit is made.
One is definitely safer than the other.
Almost all devices that switch mains power, have both the live and neutral connected to the switch.
Almost…
One wire is live in that it moves between —x and +x volts in a sine wave. The neutral is often connected to earth/ground somewhere upstream and should be 0v. So if you just pop that power into a transformer and then regulate and only use the DC then it’s completely irrelevant which way you plug it in.
However there’s plenty of cheaper ways to get a lower voltage, or to power a device from mains power that when done badly can reference what is thought to be neutral (and this ground) but could easily become live and make something metallic become live either without fault, or with fault to a minor component.