Does AC Power have Polarity?

When you're looking at an AC source in isolation such as in your question, indeed there's no polarity and you can connect the wires either way round.

When combining two or more AC sources in series or parallel, the relative phasing is very important.


As long as you are dealing with a closed system (like a transformer secondary winding + bridge rectifier) then no, AC is not polarized.

However, when dealing with outside power (like what comes out of the wall) we do consider AC-carrying cables to be "polarized". There's the hot wire carrying the juice and the neutral wire carrying the return. The hot wire should go directly to your device's switch / fuse, and any semi-exposed contacts must have the hot wire as protected as possible. If you don't do this on production items you will fail UL certification and be wide open for lawsuits. The common light bulb would likely fail many of today's standards, but it's been around too long to recall.

Devices that don't have a polarized wall plug will use a double-pole power switch to prevent the circuit being live up to the switch.


AC voltage has no polarity. Therefore it does not matter how you connect the wires to the bridge rectifier. Also, there are no dumb questions. Feel free to ask about whatever is bothering you. You will learn, as will others, and you will be safer for it.