a companion discussion area for blog.codinghorror.com

A Fistful of Connectors


Loyd Case recently noted that the standard 3-prong computer power connector is.. not so standard any more:

This is a companion discussion topic for the original blog entry at: http://www.codinghorror.com/blog/2006/04/a-fistful-of-connectors.html


To a certain extent that’s true, but your garden variety standard sized cable can easily carry anything from a millivolt to, er, lots of electricity (1.21 jigawatts?! Great Scott!).

So there’s really no good reason for a dumb two-pin power cord to have a keyed connector.


It’s unusual to get male connectors on the live end of cables because you don’t want live metal pins lying around where they can easily be shorted out. In a female connector the live connections are protected and therefore much harder to accidentally short.

I guess the hermaphroditic connectors would need to have the live connections around halfway down the “pin”, on the “inside” so that you can’t easily splash them and short out your power supply. To me this sounds like an expensive alternative. But I agree with the potential advantages of such a design.

I share your pain with USB, I always have to stop and think and look; which, to me, says that the design is broken…


I have yet to learn which way ‘up’ actually is. If I’m trying to plug something in at the back of my computer under the desk I stand next to no chance of getting it right first time.

Larry Page shares your opinion on more universal power cables. He’s probably got a bit more clout in this area at getting something sorted. Then again, probably not.



I was at a Douglas Adams keynote a few years back, and he pointed out that there is one universal power adapter in common use.

The cigarete lighter in cars. There’s only one type. Everything plugs into it. It provides the same voltage to everyone. Cell phones, PDAs, GPS, Radar detectors… everything that can go into a car can be powered by a cigarete lighter.

Now I get annoyed because my car only has one.

By the way… cigarete is mispelled because it claims that the correct spelling is objectional content. How dare I mention smoking.


As other commenters have already said, the ‘standard’ connector - normally just referred to as an IEC here in the UK by users technical enough not to just call it a ‘kettle lead’ - is IEC 60320 C13 (cable end socket) and C14 (chassis plug). Actual kettles generally use C15/C16 which have an extra channel/lug to indicate the higher temperature rating. The less-standard connector is a C5 (socket)/C6 (plug).

As for your two-pin connectors, two of them are also from the same standard; there’s definitely a C7 there and one of the others looks like a C1. Most low-ish current double-insulated equipment comes with a C8 inlet over here.

A downside to the C13 is that it doesn’t latch, making it possible to knock the connector out. Some designs of line socket are compatible with a latch cage that mounts to the chassis plug which simply clips over the back of the socket when connected, to reduce this possibility.

As to why they do it - probably to force you to buy an overpriced power cable from them rather than use a standard one. It doesn’t exactly save any space.


Not that standardized though, just come to the UK or anywhere else in Europe…


Thanks for silently stripping my link.

Here’s the Douglas Adams article: http://www.douglasadams.com/dna/980707-03-a.html


I got an iJuice for Christmas from my wife. Since using it on my phone, the phone will not hold a charge as long as it previously did (and this is after replacing the battery). In addition, my tablet’s battery life seems to have been reduced as well. The customer service on getting information on tips from iGo is non-existent. Buyer beware.

Great idea, but I haven’t had good luck with it. I just got a new tablet and I’m very leary about using the iJuice with it.


I assume that Dell either found out that power cables were often lost (common for notebooks, but I’d be surprised if it was common for desktop PCs), or that the cheap power supplies they use often blow up (more likely), and they’re trying to cash in on them as expensive accessories. I think it’s pretty obvious why other companies don’t get together and standardize their connectors – there’s probably a lot of money to be made in accessories, second power cables, etc…

Of course, it may not be so sinister. Maybe there’s a usability issue with the standard PC power cable that Dell has discovered from their support data. I’d find that hard to believe, though…


The ‘new’ one in the top picture has been around for years. Apple used to use it for their older PowerBooks. (Back when the Apple logo was the way up dictated by ergonomics, rather than the current superficial aesthetic-driven orientation.) My current IBM ThinkPad uses the exact same plug. (In fact I’m using an old Apple power cable with my ThinkPad right now.)

If Dell are moving in this direction, that’s actually a positive step. My Dell Latitude D800 uses a bizarre three pronged setup that is essentially the standard 2-pin figure of 8 (which is ubiquitous here in the UK; I’ve never seen any of those other 2-pins you show) with the third pin in line with the other two, rather than stacked in the middle. I’ve never seen this on anything else. (Not even on Dell’s other laptops!)

The ‘standard’ 3-prong connector is often described as a ‘kettle lead’ in the UK because almost all kettles use them. (Although strictly speaking, kettles required the high-current variety, which have a little notch cut into the flat edge in line with the earth pin. However, you can use the high-current leads in computers just fine.)

I’ve never seen a laptop that uses the ‘standard’ kettle lead. All the laptops I’ve used have either had the figure of 8 2-pin, the ‘new’ 3-pin you show here, or Dell’s bizarreo Latitude-D800-only inline 3-pin.


Actually, the industry tried a hermaphroditic connector many years ago, it was used called the Token Ring connector. Look where that wound up!


The reason for non-standard is the reason for anything else, Money!!! Like you, I’ve noticed that sometimes companies ships with different power cables or even USB cables, so that if you need a new one, you have to get it from the manufacturer. If they were standard you could get them from anywhere else.

But answering to Doogal about non-standard power connectors on US, Europe or UK: You don’t want to connect a Europe’s desktop PC to a US outlet. They use different Voltages and you would burn out the equipement.


Re: USB; supposedly the USB “logo” is on top of the connector, so it should be facing up when you plug it in to most things. Of course, that’s all for naught if you have verticle slots. (for instance, on my Gateway Profile, my USB ports face the back of the machine.)

As for the main topic: I completely agree. As an exercise, try to buy one of those funky rounded things, I believe they’re called a C-4 style cable. (that’s a better hint than I had!) It took me the better part of a morning to even fine out what they were called, nevermind how to get one.

They’re all too common on laptops and projectors too. It’s a shame there will probably never be a standard similar to USB, i.e. the regular and small USB-B connectors; those are only occasionally screwed up. (Hello, Pentax!)


I remember seeing this question raised elsewhere before. I’m fairly certain there was something about voltages? I wouldn’t want to spread misinformation but other vendors do use this and it does appear to be a standard.


If you view the PDF for AC power cord-3prong US Standard you’ll see it detailed somewhat. From there I’m sure you could find out information about the standard.

Of course I may very well be giving them the benefit of the doubt here… But I’m no EE so I’m not sure where else to really look for more detailed information about these cords.


Actually more information can be found here:


The key terms seem to be the “WS-083 connector” and “IEC-360”.

Perhaps the best information yet I’ve found is


Thing is, none of those connectors are expensive. There’s a place here in town that sells a variety for $1 each!


True. I have way more clout than Larry Page.

(I know it’s not what you meant, but I couldn’t resist the misinterpretation :wink:


I always thought that that the plugs were different because the cables carry different voltages and amperages.


Most of these connectors go in the back of the machine. IMHO, they should be designed so they
can be orientated by touch. Not only would it help visually impaired and blind people, but it would help fully sighted people working in bad light and cramped conditions. Or doesn’t anyone put the “tower case” under the desk these days?