How can I lock an extension cord into another extension cord?

December 5, 2014 6:33 PM

I want to lock these two (white to yellow) extension cords together so that nobody can unplug them unless they have a key.

I have an ebike that needs a significant amount of time to charge. I have run a cord out my window (down 6 stories) and many people use it to charge their bikes. I don't care, I don't pay for electricity. The only bad part is that they sometimes unplug my cord in order to plug theirs in, even though the white wire leads to a 8-outlet power strip. My bike requires around 8 or 10 hours of charge to get a full charge, and my plans today are now ruined because it seems my bike didn't actually charge over night even though I plugged it in around 9pm.

I really think that the best solution is to somehow lock the power bar and the yellow extension cord together with some kind of padlock, so that nobody can unplug it on me. It is coming from my window, and I could unplug the power at any time, so I think I have the right to do that. Things that I can't/won't do include:
- take the bike or battery inside. the bike is too big, and I don't know how to disconnect the battery (I can't even see it, it's deep inside the bike)
- unplug the cord when I'm not using it - it doesn't really solve the problem as they'll still unplug my bike
- write a note and post it outside explaining/talk to the people involved - I'm in China, my Chinese isn't great, I don't know the people, and honestly a note would be ignored

So how can I lock the two extension cords together? If I just put a padlock on the two cords, you could still pull the plug out of the socket, so I'm at a loss. Any other suggestions are welcome but I'd really like to know how to lock the cords together.

posted by sarae to Home & Garden (14 answers total)

A small box that is lockable. Drill two holes that will fit the cords. Plug, lock. Add danger symbols for good measure.
posted by sammyo at 6:41 PM on December 5, 2014 [2 favorites]

Could you superglue the two together?
posted by sciencegeek at 6:43 PM on December 5, 2014

So, do you explicitly want to leave some outlets available for other people to use? Because otherwise the obvious solution seems to be hiring an electrician (or doing it yourself if you're so inclined) to splice the extension cord right into the charger cord, effectively lengthening the cord of your charger so it reaches into the house and eliminating plugs from the mix altogether. If you do want to continue to provide charging to people in your neighborhood you could also splice in a surface mount receptacle box like this, keeping your own charger hard-wired to power by cutting off the plug and splicing it into the back of the box .
posted by contraption at 6:44 PM on December 5, 2014

Response by poster: Not to threadsit (going out for a while) but a couple more details:
- the cord actually isn't mine. There are several of us who live in the building who need to charge our bikes, and we share the cord. The problem is random people who work here who unplug our bikes in order to charge their own.
- I want to be able to unplug my cord when necessary
- I can't do wiring, and hiring an electrician is out because of the language barrier

So far I like this box idea!
posted by sarae at 6:58 PM on December 5, 2014

Things like this are used for safety situations with multiple workers, search for "lock out tag out box" that can take an item, or cords, and then lock them into it.
posted by nickggully at 7:14 PM on December 5, 2014 [1 favorite]

What you want is probably something like an enclosure box. Dri-Box is nearly perfect, but they don't have locks.
posted by zamboni at 7:27 PM on December 5, 2014

The easiest and cheapest solution (though not necessarily to code, but neither is a six story extension cord hanging off of your balcony) would be to cut off the plug on the end of the extension cord and just wire the power strip (or a couple electrical outlets in a box if that was easier) directly to the end of the extension cord.

As long as you aren't worried about being up to code it's an easy DIY job. That way there's nothing to unplug and plenty of outlets for anyone to plug into.
posted by Dip Flash at 7:29 PM on December 5, 2014 [2 favorites]

Best answer: How often do you need to unplug the white cord? Zip ties in an X-formation would do the trick, I think. They probably wouldn't carry/use wire cutters to plug in, right?

You just need to make it a little more challenging, and then they'll unplug someone else instead.

How about just branching off more sockets? I mean, if there are enough available, they won't need to unplug yours.
posted by supercres at 8:10 PM on December 5, 2014 [1 favorite]

This is a really terrible 30-second illustration of what I mean by X-formation, by the way.
posted by supercres at 8:15 PM on December 5, 2014

Last thought: if you can find a long-shackle padlock in just the right width, you'd be set.
posted by supercres at 8:16 PM on December 5, 2014

A cheap lockable plastic tool box (like this Stanley) is only a few bucks and could be easily modified with a series of slots to allow the cords to enter/exit. A large rat tail file available in the same aisle as your toolbox would be an easy way to cut slots if you don't have access to power tools.
posted by Mitheral at 9:20 PM on December 5, 2014 [2 favorites]

You're not going to be able to stop someone determined or wilfully thoughtless from unplugging your bike. You're going to have to go with the visual deterrent. Something like a light chain attached to your bike's plug, wrapped around the extension a couple of times, then with a small padlock to secure it from casual tampering. I've tried, and failed, to find purpose-made locks for AS-3112 standard plugs.

(But for the love of life itself: put a GFCI on that thing if you enjoy being not-dead. China's domestic voltage is proper deadly, and running a six-storey indoor grade extension outside is all up in the nope nope nope territory.)
posted by scruss at 5:34 AM on December 6, 2014 [3 favorites]

Not answering the question, but be careful leaving your bike battery out. Had a couple stolen in Nanjing a few years back. Theft of bike batteries was very common.
posted by msbrauer at 6:57 PM on December 6, 2014

Response by poster: I bought a new bike that requires less frequent charging (better battery). I've also put the bike on a timer now, so that it turns on around 10pm and off around 6am. Without the timer, I'd forget to plug it in or unplug it. Once they learn that it's never plugged in when they need it, they'll hopefully back off.

I can't take the battery inside as it's buried under the seat, inaccessible. I think there are several batteries in series, actually. I definitely shouldn't have a 6-storey extension cord but... it has been fine for over a year? I know, that doesn't mean anything, but... I find I take less precautions now, living here. AND I have no idea where/how to find a GFCI and what even to do with it...
posted by sarae at 2:13 AM on January 20, 2015