On my last trip through Chicago’s O’Hare Airport I got fooled by the mystery outlet depicted in the photo. At a distance it looked like an AC power outlet, but it’s not one of these. Annoying, because I’d rather spread out on the floor than crouch among the huddled masses at the power bar. What is that thing anyway?
September 28, 2007
September 28, 2007 at 2:17 pm
I’m fairly certain those are 20-Amp twist lock outlets, but I’ve never seen them in quite that form factor (two on one block where a standard wall faceplate would slide over them).
September 28, 2007 at 2:26 pm
These are high-voltage (nominally 220V) circuits that use three separate idiot-proof methods to avoid blowing up something not intended to receive that voltage. First, no parallel blade ungrounded 110V plugs can be inserted because of the shape. Second, the leads are recessed so that even the biggest idiot can’t manage to make contact with them. Third, you have to lock the plug in place to make contact, which means you don’t get arcing which could be dangerous at that combination of volts and amps.
Here’s a page with various tech specs. Neat subject area.
September 28, 2007 at 2:27 pm
Not to sound facetious, but that is danger in electric form. Any kind of twist lock is for either higher voltage or higher amperage power. They may use this connector for anything that uses large electric motors, like enormous floor buffers and such. Definitely too much for a laptop power adapter.
September 28, 2007 at 2:28 pm
Looks like a locking AC plug for commercial cleaning equipment or something. Maybe they are these:
http://www.levitonproducts.com/catalog/dept_id_998/model_2610-IG.htm?sid=F51EC4EF387726C27E9652B5D44F30D1&pid=1208
But in a dual faceplate form factor.
You should look into an adapter to bring it back out to a normal 3-prong. Carry it with you for next time. :)
September 28, 2007 at 2:38 pm
Further investigation led me to this PDF file with diagrams:
http://www.elect-spec.com/nema_twist.pdf
The pattern of the blade sockets, and the diameter of the plug if it fits roughly in a household sized faceplate would lead me to believe it is a NEMA-L5-15R socket. Possibly rated at 125volts and 15 amps.
September 28, 2007 at 2:51 pm
Here Jon,
Check these adapters out… the L5-15R that Eric mentions is right I think…
http://linkpot.net/asphalts
or even better:
http://linkpot.net/hosed
September 28, 2007 at 3:46 pm
Every laptop power brick I’ve ever examined has been rated for use at up to 240V (handy because that is standard house mains for most of the world). The amps that a power supply pulls when operating in its rated voltage range is dependent on the power it requires, not on the size of the upstream circuit breaker. You wouldn’t enjoy shorting this power through your body (I can’t say that I’ve enjoyed my experiences with “normal” 110V), but I think you could use it to charge your laptop, given the appropriate adapter. That adapter may not be available for purchase in the USA, because it would inherently defeat the safety features of this type of outlet.
However, the reason that O’Hare has these outlets probably has far more to do with the fact that management doesn’t want you using them. They don’t want people sitting on the floor in that area, they don’t want to provide free power, and they don’t want the janitorial staff to have to evict people from the power outlets. If you do obtain an appropriate adapter, getting caught using it will probably enable airport security to seriously inconvenience you. If you plug into a normal outlet, all they can really do is make you unplug.
September 28, 2007 at 5:08 pm
This was all very enlightening. Thanks for the excellent comments!
September 28, 2007 at 8:32 pm
“Check these adapters out… the L5-15R that Eric mentions is right I think…”
Tempting. But I think Jess got it right w/respect to airport security.
September 29, 2007 at 7:41 am
Those are the same outlets you’d find on the outside of travel trailers to connect up to the main power source and I’d assume like others it is to handle higher voltage/amp.
September 29, 2007 at 12:33 pm
Give the number of electric carts running around O’Hare,
they are probably dedicated for charging them.
it’s a bit hard to tell from the pix, but it looks like a
30-amp twist-lock. it *might* be a 3-phase 30-amp,
but that’s less likely, unless the charger idea is right.
some large chargers do use 3-phase.
September 29, 2007 at 8:18 pm
Jon,
You just needed to check out a different entry on Wikipedia…
http://en.wikipedia.org/wiki/NEMA_connector#Twist-locking_connectors
Doesn’t have to be high-voltage: this could be a standard 120VAC outlet, but using the twist-lock so that when the overnight crew cleans the floors they don’t have to worry about pulling the plug out of the socket. Should be easy to build a connector from a regular 3-prong socket to a twist-lock…
October 1, 2007 at 1:24 am
Oooo, scary, 220V.
Got to laugh, only the USA seems to be frightened of the 240-250V standard that the rest of the world seems to use!
October 1, 2007 at 7:15 am
[...] Jon Udell: Mystery outlet at O’Hare [...]
October 1, 2007 at 7:53 am
The standard RV 30A connector is the TT-30, which does not twist lock.
The link from Bret ( comment 12 ) goes to wikipedia right below the section on RV sockets.
Lots of server rooms ( like mine…) use twist-locking sockets like those to try to prevent cords from being accidentally pulled out of the socket. All of my Power Distribution Units ( like an expensive power strip…) have either L5-15, L5-20 or L5-30′s.
I agree, it should be easy to build an adapter, or you can just buy them.
http://www.stayonline.com/detail.aspx?ID=3102
October 2, 2007 at 8:12 am
Starbucks compatible twist AC outlets for portable coffee stands that overcook/burn coffee at high prices? Now to figure out why their airport bagels are always stale….
October 3, 2007 at 3:24 am
Is it possible that you flipped the image (so that it’s the mirror image of the actual socket)? I ask because the radial notch is on the anti-clockwise side of the notched prong, whereas all of the references posted seem to place it on the clockwise side.
September 14, 2009 at 2:36 am
Forgive me for commenting on a two-year old blog post, but I wanted to add to some of the information in previous posts for anyone else that comes across this (perhaps one of you is in O’Hare reading this blog right now?).
As many other commenters have since suggested, the plug you’re looking at is almost certainly NEMA L5-15, which is essentially the twist-lock version of the same mains power that every household in the US is used to. Even if the receptacle was a strain of L6 (which is rated at 250V), most laptop power adapters today will handle either 120/240V standards without blinking. 240V is in fact safe for almost all modern laptop power supplies, but you should always check the rating on your device before plugging it in. Better yet, if you have a voltmeter, measure the voltage directly before plugging anything into a foreign outlet. Just note that having a voltmeter in your carry-on luggage does, in fact, make you a big nerd.
Also, as an amusing aside, regarding (comment #2) Glenn’s note about these receptacles being effectively idiot-proof… the last time I traveled through O’Hare, I watched in horror as a fellow passenger gleefully shoved her two-prong MacBook power plug into that exact receptacle type until it “fit”. Funny thing is, possible bent prongs aside, the MacBook and the power adapter didn’t seem to mind one bit about the power it was receiving — yet another (anecdotal) clue that the voltage from those outlets does not exceed 240V.
September 14, 2009 at 9:58 am
> Forgive me for commenting on a two-year
> old blog post
No apology needed! One of the delightful aspects of this medium is that it can fold time as well as space.
> Just note that having a voltmeter in your
> carry-on luggage does, in fact, make you
> a big nerd.
Ya think? :-)
> I watched in horror as a fellow passenger
> gleefully shoved her two-prong MacBook
> power plug into that exact receptacle type
> until it “fit”.
Chuckle.
Well the situation at O’Hare seems to be improving but it’s still highly variable on an airport-by-airport basis.