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I live in Japan, which uses plugs A and B for mains connectors, and I will be going to South Korea, so I decided to buy a plug adapter for my electronics.

Searching online, all points that South Korea uses the same plug as Europe, which is type C. I've been to France and South Korea before, and it indeed seems that they both use the same plug.

However, when I went to buy the adapter, there seems to be another type called SE, which is marked for use in "Korea, France, Netherlands, Germany, etc.", while the C type is marked for use in Italy and other countries I can't remember now, but notably omitted South Korea.

It doesn't seem like "SE" is another name for "C" depending on the brand, since many brands seem to have both "C" and "SE" adapters. Check for instance this SE adapter and this C adapter from the same brand.

Based on the pictures, it seems like the SE adapter has slightly thicker prongs than the C plug.

I also couldn't find any mention of an SE adapter in English, but it is interesting to note that searching for "SE plug type" leads to C plug type related pages.

Eventually I trusted the label and went with an SE adapter, and I suppose it will work fine. But I was left curious. What is this SE plug, and what is the real difference with the C plug?

  • I've had many experiences in some countries where these "two round prong" plugs just fall out of the sockets. So I've also thought there must be a slight difference in prong size between two otherwise similar standards. As well as poorer quality plugs and sockets in some places of course. South Korea is generally up to European standards though so I wouldn't worry about plugs falling out there. In India it was a big problem if I remember rightly. – hippietrail Sep 9 '15 at 3:28
  • Worth noting, we have a related question: travel.stackexchange.com/questions/34205/… – Mark Mayo Supports Monica Sep 9 '15 at 3:39
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    @hippietrail: Note that on European plugs, the prongs are usually ever so slightly angled in a way that they are a tad closer together at the tip than at the base (it is slightly visible on this photo). Therefore, it's not necessarily a difference in prong size so much as the lack of mechanical "clamping" to the socket when the prongs are not angled. – O. R. Mapper Sep 9 '15 at 9:20
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    @hippietrail The issue with European plugs is actually quite simple: many international adapters do not conform to the specification, which is that either (1) the adapter supports the grounding pin for type E or the grounding mechanism for type F (which both hold the plug in the socket), or (2) if you are using a device with type C plug, the pins are slightly angled and have a thinner plastic part, as visible on en.wikipedia.org/wiki/Europlug. Two-prong all-metal-pin international adapters are neither, so they can fall out. – DCTLib Sep 9 '15 at 9:36
  • The two flat prong style plugs used in various countries such as Mexcio and here in Laos also often have this problem. I'm thinking of buying an extension cord for the times when the socket is high and the adaptor and/or power supply/charger etc is heavy enough to make it fall out. With an extension the heavy bit can then be on floor/table/etc. Anyway the socket in my current hotel is nice and tight so no probs (-: – hippietrail Sep 9 '15 at 9:50
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The concept of a "Type SE" seems to be a Japanese thing: the canonical list of plug types is maintained by the International Electrotechnical Commission, and they don't recognize it.

The best source I could find, then, is this random Japanese site, which claims that Type SE is identical to the Type C, except that:

  • Type SE plugs have may have a hole for a ground (earth) pin in the middle
  • Type SE plugs may have slightly wider pins than Type C

On closer observation, it looks like "Type SE" is identical to what is usually called "Type E"! Type E, which originates from France, has the grounding pin hole and straight 4.8x19 mm pins, while Type C lacks the hole and has slightly smaller, tapered 4x19mm pins. Side by side:

enter image description hereType C enter image description hereType E/SE

  • Interesting that it is more related to the E plug than the C plug. It's like SE is a non-grounded E. You may want to fix the link to the canonical list of plug types, as in my environment, it redirects to iec.chworldplugs (without a slash). The correct link would be iec.ch/worldplugs . However, I can't make a one-character edit... – Panda Pajama Sep 9 '15 at 4:50
  • @PandaPajama Link fixed, thanks! Didn't quite follow you there, what difference do you see between SE and E? The grounding pin is allowed in both, only it's in the socket, not the plug: iec.ch/worldplugs/typeE.htm – lambshaanxy Sep 9 '15 at 5:24
  • I'm not entirely versed in this, but I suppose types are for both plugs and sockets. That is, a type A plug will work with a type B socket, but not the other way around. I am just hypothesizing that "type E" is "grounded 4.8mm wide", "type SE" is "ungrounded 4.8mm wide" and "type C is "ungrounded(?) 4.0mm wide". In that case, "SE" would be more related to "E" than "C", much more like the difference between "A" and "B". – Panda Pajama Sep 9 '15 at 5:30
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    It's also very interesting to note that the "B" plug type according to the Japanese page you sent has nothing to do with the IEC "B" type. It seems like the Japanese have names totally independent from those of the IEC. – Panda Pajama Sep 9 '15 at 5:50
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    @PandaPajama Standards are wonderful, there are so many to choose from... and this apparently extends to meta-standards describing other standards! – lambshaanxy Sep 9 '15 at 7:05

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