I have a laptop power supply that comes with a US 3-prong plug, connected to the PS through a 3 circle female connector. I want to change its plug from US 3-prong to UK 3-prong.

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But, if I am not mistaken, the UK plug and the US plug has reversed Live/Neutral. Looking at the wall socket, with the earth on top. The Hot/Live is lower left. But for a UK socket, the Hot/Live is the lower right!

After I cut open the wire, I naturally connect the green to the EARTH, black to LIVE and white to NEUTRAL. But this will cause the Live/Neutral to be reversed as it enter the power supply. Experience with travel adapter suggest that it works just fine. Am I missing something?

(Yes, I understand UK and US also have different voltage but the laptop P/S can handle both)

  • 3
    \$\begingroup\$ That is AC and your adapter is not polarity sensitive. It will work either way. The critical wire is the earth ground. \$\endgroup\$
    – Gil
    Commented May 17, 2022 at 2:03
  • 4
    \$\begingroup\$ Why not just get an IEC 60320 C5 to BS 1363 cord? \$\endgroup\$
    – Hearth
    Commented May 17, 2022 at 2:03

1 Answer 1


As noted in a comment: just get an IEC 60320 C5 to BS 1363 cord. Do not try to cut the cord and swap the plug - simply not worth the risk, and the cost of an actual manufactured cord should be extremely low. Just make sure to look for an appropriate certification - in the US that would be UL or ETL, but I'm not sure what the equivalent is in the UK.

But as far as the theory goes, for all practical purposes*, in normal use an appliance (laptop charger, lamp, toaster, whatever) can't tell the difference between the hot (or live) wire and the neutral wire. Unlike DC polarity, in AC there is no easy way to tell the difference except by comparison with the ground (earth) wire. In fact, some devices (US: NEMA 1 unpolarized) don't even have a ground pin and are designed so that hot and neutral can be interchanged with no effect on usage or safety. There are certain designs - e.g., screw light bulb fixtures - where hot vs. neutral does make a difference, and any such devices are (at least in the US) supposed to use properly wired polarized plugs (or grounded plugs, which enforces polarization) for safety.

But for a typical laptop charger, it likely makes no difference. In particular, there are no exposed metal parts, and the other end of the power "brick" only has low voltage (typically 19V).

  • \$\begingroup\$ The reasons are 2 folded. 1) to save money. If I actually try to buy a cable like that, it will cost me US$20+ including shipping. Also, 2) I have many spare UK plugs from old appliances and by making my own, I keep them away from landfill. Wish I knew the name of the plug (IEC 60320 C5). But when I look it up (en.wikipedia.org/wiki/IEC_60320), it says it is polarized. I can't find its pin out. But I agree that polarity can be ignored for laptop P/S. \$\endgroup\$
    – some user
    Commented May 17, 2022 at 2:30
  • \$\begingroup\$ I realize the pricing is a bit crazy. The real price (relative to everything else in a laptop) of a laptop charger should be $10, and there are some retail (excluding the true junk) in the $20 - $30 range. Of that, the cable should be something like $1 - $3, not $10 - $20 all by itself. I have dozens (used to have more, finally tossed a bunch...) of C13 (as opposed to the C5) to NEMA 5-15 cords lying around, not so many C5. \$\endgroup\$ Commented May 17, 2022 at 2:38
  • 2
    \$\begingroup\$ Even at USD $20, a good quality non-modified cable is surely cheaper than the potential costs of failure/fire/injury. \$\endgroup\$
    – JYelton
    Commented May 17, 2022 at 15:32

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