When plugging an AC to DC converter into an AC outlet, does it make any difference at all if the wall wort is "upside down" or "rightside up"? Is there anything about the electrical design that would result in the orientation making any difference?

Most of the time, there is an obvious "rightside up" where all the writing is in one direction, and the AC plugs are closer to the top.

I would assume that the answer is independent of what the AC to DC converter powers. Is that assumption correct?

Does it make any difference at all when the AC to DC converter is powering computerized "smart" DC battery chargers?

In all the above, assume each converter has two AC prongs of the same size (none wider than the other) and each converter only has two prongs (no separate ground prong).


closed as off-topic by Brian Carlton, PeterJ, Leon Heller, nidhin, Nick Alexeev May 25 '15 at 1:13

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  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – Brian Carlton, PeterJ, Leon Heller, nidhin, Nick Alexeev
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  • \$\begingroup\$ The right way to plug it in is the direction that doesn't block the other outlet. \$\endgroup\$ – Pete Becker May 23 '15 at 2:05
  • 1
    \$\begingroup\$ Assuming you are in the USA and both prongs are the same size, then it doesn't matter. If one prong is larger, then it should match the outlet. \$\endgroup\$ – DoxyLover May 23 '15 at 4:27

It shouldn't matter.

Regardless of orientation, the voltage coming in will be a varying sinusoidal voltage and thus looks the same either way to the transformer, the next component in line after the physical plug. In fact, every component in the wall wart should operate just like it normally would whether the wall wart is upright or upside-down.

If your wall-wart isn't operating the same based off of orientation, I'd stop using the wall-wart.

  • \$\begingroup\$ Thanks. I especially like how you wrote the last sentence. I believe I'm paraphrasing you correctly if I say: "If it doesn't work identically in both orientations, it's broken and shouldn't be used in any orientation." \$\endgroup\$ – RockPaperLizard May 23 '15 at 3:22
  • \$\begingroup\$ Yup! Your paraphrase is correct. \$\endgroup\$ – Funkyguy May 23 '15 at 3:23

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