So have you at the very least photographed/videotaped the cord yet, preferably with a time/date-stamp embedded within the image? Seems to me all the mind games going on in this thread are taking a precedence over the reality. Abuse of electricity has some life and death consequences. It would be a pity to come back to find your property damaged, or your place burned out, because you did not document and not report this to the landlord, utility company and/or the police. I’ll finish the pile on with this. Something happens to your property in all this silliness and your insurance company refuses to pay for damages because you didn’t take due care with your own safety.
Turn just about everything on in your apartment. Make sure the stove and AC are on and running. The meter spinning like a top is probably yours. Now go turn everthing off. Is that meter now moving much less? Thats probably your meter.
The hidden thing that might throw you off is your water heater if it is electric. To turn that off you generally need to throw the circuit breaker.
Or, you know, talk to your apt manager and have him/her show you were the meter is. If you explain to them that you want to figure out how much electricty is being stolen before they act on it, I’m sure they’ll take that into consideration. They may also know stuff about your neighbor that you don’t.
Also his refrigerator. Several appliances draw small amounts of power when plugged in, even when turned off, otherwise remote controls wouldn’t work.
Yes, that too. Pretty much all electronic boxes need to be turned off then unplugged, because as you said they draw power just sitting there and a bunch of them can add up.
There, there dear. It’s okay.
Erm. Got any cupcakes left?
Considering my sister and her two kids lived for the last six months with no electricity whatsoever in their apartment, I’m beginning to suspect that she might not have been
COMPLETELY without it.
What if he climbs onto your patio and steals the meter?
Personally I don’t see why it’s any more complicated then unplugging the cord and tying it in a knot, maybe tossing it back up onto his balcony. And then informing the landlord of what happened, with the expectation that if it happens again the landlord will be responsible for dealing with it.
Of course it wouldn’t be nearly as fun a thread that way. 
What would happen? I know next to NOTHING about electrics. Feel free to snark on me. 
Dude, forget the meter and just call the fucking cops. This thing sounds like a fire hazard just waiting to happen.
Have you even seen the neighbor? Are you sure it’s a guy? Perhaps your neighbor is some beautiful lonely coed who finds that battery power just isn’t enough to satiate her daily carnal needs, and she’s using your outlet to power her Kongster 4000 because she’d be too embarrassed to explain her outrageous power bill to her wealthy parents, who just happen to own the #1 internet gaming company/local micro-brewery/steakhouse on the planet.
I don’t understand all of the beautiful coed hate.
That’s a good point - maybe check the neighbor out by pretending to be a pizza delivery boy.
“Greetings, Lonely Coed. Allow me to introduce myself: I am Senor Beef, your neighborly energy provider.”
Now Senor Beef is quite glad to have ignored all the advice for cord yanking, 220 zapping, authority calling.
Frankly, the OP has lost any sympathy from me about two days ago, when he ignored the 99th person who said, “inform your landlord.” Take a fucking picture, call the fucking landlord, and be done with it.
The argument, “No, I want to see how much he’s stealing so I’m going to do nothing for a week, and let him steal a lot more” is inane. Odds are that he’s gotten $50 or $100 of your power, max. You’ll never get that back, so start taking action now.
At this point, I hope he has an entire server farm running up there.
The person you are dealing with is either desperate, or lacking in conscience, or both. You need to proceed very cautiously, and be sure that whoever takes action has the authority to do so decisively. I’m thinking police, not management or electrical service; although I woudl inform the other two.
First order of business is to take a hard look at the locks on your patio door and windows. You already know that this guy can and will drop down to your patio for nefarious purposes.
Second is to put up a camera that can “See” the outlet.
Then unplug the outlet, but leave it partially in, so it looks like the plug just got yanked loose or something.
Obtain tape of neighbor re-plugging and adjusting the cord.
Then call the police and tell them what’s up. Definitely press charges.
That’s my $.02
Also, do you have a friend who can house sit while you are gone? This is not a good time to leave the place unattended.
Some one (else) has been reading the ‘Ask the Porn Director’ thread.
That won’t work since AC by definition doesn’t have a polarity; “hot” or “phase” and “neutral” simply refer to the potential referenced to ground; that is, neutral is grounded and phase isn’t. Most devices won’t even notice any difference because of this, even with 120 volts between neutral and ground since they should be separated (ground should only conduct if there is a fault). Some exceptions are things like lamps, where the outer screw part is connected to neutral, so it would now be live (even when turned off), so a shock hazard would be present; two-prong appliances may also give a tingle when touched if the case is connected to neutral through a capacitor/resistor to bleed off charge (some may do so anyway if the plug isn’t polarized, this isn’t a hazard unless a short occurs).
Or maybe certain contractors don’t need a “five man crew” to stand around for “half a day” before coming up with the bright idea to dial the owners number and say “we need to snip a lock”. Could that be it?
Some people are more self-directed and able to problem solve a bit more readily than others.
Dude, you don’t know how much he’s using, you never will, and you’ll never get compensated for the power he’s stolen. That ship has sailed; all you can do now is stop him from getting more of your electricity (and possibly get him booted out of your complex).
Also, what he said. 
I don’t know about that. I’ve seen civil suits that have paid off for theft of services, but you need to show utility bills before and after that show a recognizable difference.