Cords
Cords
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So if these are people wiring their Christmas lights wrong, assuming these are led lights, doesn't this "solution" not work bc of the polarity anyway? Or is that only a DC thing with diodes? I only did okay in my physics electricity stuff lol
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For simple stuff such as those lights, polarity is usually not a problem when using AC.
In case of AC (Alternating Current), instead of having a + and - pole, you have a Line and a Neutral terminal.
The Line terminal goes + ... - ... + ... - ... + ... - with time and the Neutral stays at 0.
When connecting to LEDs and such, you have an AC to DC converter, which tends to be fine no matter which pin you put in which hole.
Edit for clarity: I am talking only about the specific appliance in this case, having a 2 pin plug. When doing home wiring, polarity matters a lot.
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Ah, so that's why it's half power compared to DC, makes sense.
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Kinda, it's half the power because the power goes like the temporal average of the current squared, the current oscillates like sine or cosine, and the temporal average of a sine or cosine squared is 1/2.
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Unless the AC is a square wave, in which case stuff becomes different.
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- Not really.
- Where on earth would Mains be a square wave?
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Low quality UPS Inverter
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That's not what Mains means.
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As far as the appliance cares, it is the only input power it gets at that time.
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In household wiring polarity does matter, especially if you are assembling plugs. Only one of the three wires is carrying live current (hot), the other two are the neutral return path, and ground which is for safety. If you accidentally switch polarity, you can cross hot to neutral and cause a short circuit.
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Switching the neutral and hot pins doesn't matter except for appliances with exposed metal tied to the neutral pin, which is pretty much exclusive Edison screw lamps. This is why many plugs (especially those that immediately go to a rectifier) don't bother with polarization.
Swtching hot and ground is a problem
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My bad. I wasn't clear enough.
I was talking about 2 pin plugs, as shown in the post and how it is usually for those cheap lighting thingies.
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No, alternating current doesn’t have a polarity like DC does.
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It would still work. But it is VERY dangerous. 1. The far end of the light string will now have exposed metal prongs that are energized at 120v, which can be fatal. 2. If the other end gets plugged into a socket, there is a 50% chance it will be a different circuit on a different phase, which can create a 240v direct short, across a wire that has no properly sized circuit breaker. 3. Using it to plug a generator into your house during a power outage can kill electrical workers trying to fix the outage if you fail to open your circuit breakers.
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I knew that much, I was more interested in how diodes work on AC lol
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In AC, diodes work half the time, every 1/60 second. The "good" LEDs will have circuitry to fully rectify the AC into DC, drop the voltage properly, and smooth the peaks and valleys, so they will be continuously lit. So the cheap LED Christmas lights might have a slight flicker, and the good ones are steady. (Or get fancy with chasing colors, etc.)
All of that happens inside each of the "bulb" enclosures, or sometimes in a box at one end, so it technically doesn't matter which end they are getting electricity from, since the socket at the far end is still just connected in parallel to the plug at the near end. (Otherwise you wouldn't be able to link them together.)
It's just a really bad dangerous idea to reverse them.
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210 comments