8

Inspired by this question asking about "regular" power cables, I have been curious about (read: irritated by) the rise of "Mickey Mouse" power cables.

Apparently they come from the same standards document (C14 and C6, respectively), but I cannot recall having seen the C6's for as many decades as the C14's. On the contrary, I do recall laptop power bricks using the same C14 socket as other IT equipment until "somewhat recently" (in a retro computing sense, that is).

Can anyone explain why we started using this other socket shape?

"Mickey" C14 on the left, "standard" C6 on the right

"Mickey" C6 on the left, "standard" C14 on the right

  • Do you have a photo? I don't know what Mickey Mouse power cables are. – Greenonline Jul 5 '18 at 18:10
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    I am voting to leave open. If Why did computers use a power supply with a socket? is valid, then this question should be as well. – Greenonline Jul 5 '18 at 18:12
  • @Greenonline well I wouldn't say the question you linked is on topic at all. – Wilson Jul 27 '18 at 14:39
  • @Wilson - OK, vote to close it (or both) then... :-) I was merely pointing out a possible inconsistency. – Greenonline Jul 27 '18 at 14:43
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    Well in that case, thank you for being slow enough to allow me to receive replies and award an answer. :-) – KlaymenDK Jul 27 '18 at 18:26
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It's because the C14 connector is rated for higher current (10A, up to 2400W), which means that it must be attached to a thicker and thus more expensive and less flexible cable. The cable can't be rated lower than the connector for safety reasons.

The C6 can only supply 2.5A (600W in 240V countries) so can use a thinner, lighter and more flexible cable that is better for carrying around with a laptop and which is cheaper to manufacture. Most laptops require well under 100W, where as 600W is not enough for many computers.

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    "C6 can only supply 2.5A" - not true. C6 is certified by UL for 10A. – Raffzahn Jun 29 '18 at 14:47
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    UL may certify 10A but that is not compliant with the IEC spec and the IEC spec is the critical one for determining the required cable. – Craig Jun 29 '18 at 21:33
  • Presumably even UL require a 10A cable when an appliance wants to draw 10A over a connector designed for 2.5A. – user Jun 30 '18 at 16:18
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    @Craig North America does not use the IEC 60320-1 standard but instead UL 60320-1 and CAN/CSA-C22.2 No. 60320-1-11. Those specify a higher current (125V 10 A vs 240V 2.5 A on C1-C8, 15 A vs 10 on C11-C18, 20 A vs 16 on C19-C24). Even if you list with somebody not UL, you must meet the higher standards. – user71659 Jul 5 '18 at 4:18
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    @PeterGreen The power cord has to have a national plug on it anyway, so the stricter North American standard does not impact the device itself. It further makes the standard more practical to use in 120 V regions. Practically, devices have to meet the union of a large number of national standards anyway, check out the sheer number of logos on the bottom of a laptop power adapter. – user71659 Jul 10 '18 at 15:58
5

Can anyone explain why we started using this other socket shape?

It's the power rating. Or more correct, a changed power rating

DIN/IEC did original rate C14 at 10 Ampere and C6 at 2,5 Ampere. But the US standards and testing organisation UL (Underwriters Laboratories) (*1) does considere the usage of C6 with up to 10 Ampere (C14 as 15A). Thus UL certified devices/power supplied may use C6 instead of C14.

The reasoning behind is in part based on the wattage of the device connected.

This wouldn't be a big gain in itself, as the IEC standard also defines that the C5 socket has to have an inset with the same square footprint as the C14. Here as well UL did diverge and certified the usage of sockets (*2) without the inset, resulting in a somewhat smaler footprint, preferable for small external power supplies.


*1 - Well, it wasn't just them, but a combined action with the Canadian and Mexican standard bodies to create NAFTA wide standards.

*2 - IEC standard conforming cables will still fit both versions and where used by manufacturers. This resulted in a somewhat huge plug for a small socket. Soon the 'IEC part' of the plug got reduced to a slim shield covering the rectangular shape and finally (mostly) eliminated.

3

I imagine it’s because the C6 inlet is smaller than the C14 inlet: using a C6 inlet means a laptop transformer brick rated at less than 2.5 A (input) doesn’t have to be made larger simply to accommodate the C14 inlet. The C14 inlet takes up a significant amount of space inside an enclosure, compared to a C6 inlet.

  • I admit I've never seen the inside of a C6 inlet, nor considered its implications. Still, I'm waiting to see if anyone else can give a more, um, authoritative answer. – KlaymenDK Jun 29 '18 at 9:50
2

Afaict laptop power bricks with C14 "IEC" were always unusual. It's an unnecessarily bulky connector for something that only draws a couple of amps.

In my experience laptop power bricks mostly moved from the C8 "figure 8" to the C6 "cloverleaf" inlet. I am not 100% sure of the reason but I suspect that with increasing laptop power requirements, tightening efficiency standards and concerns that "touch currents" even within the safety limits could potentially cause problems manufacturers decided it was easier to move to a class 1 design.

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