Mystery outlet at O’Hare

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?

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20 thoughts on “Mystery outlet at O’Hare

  1. 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).

  2. 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.

  3. 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.

  4. 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.

  5. “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.

  6. 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.

  7. 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.

  8. Jon,
    You just needed to check out a different entry on Wikipedia…

    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…

  9. 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!

  10. 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.

  11. 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….

  12. 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.

  13. 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.

  14. > 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”.


    Well the situation at O’Hare seems to be improving but it’s still highly variable on an airport-by-airport basis.

  15. I too will comment after almost two years without a comment.

    I have to fly through O’Hare about eight times a year now. After my last trip through I took a picture of the outlet and figured out it is a NEMA L5-15R receptacle. I bought an L5-15P plug at Home Depot (Pass & Seymour PSL515P) and a 1-foot extension cord ( Cut the plug end off of the extension cord and attached the L5-15P plug. Hoping to give it a try my next trip through O’Hare.

    My guess is they use those outlets for two reasons. To keep the vacuum cleaners from pulling their cords out and also so the people who do the vacuuming don’t have to fight for a receptacle to use with all the travelers :) Pure speculation on my part.

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