The plug, the socket and the air conditioner
June 7, 2010 1:51 PM   Subscribe

Window mounted air conditioner had a burned-up blade on the plug. New replacement plug gets hot at the same blade. New plug needs to be wiggled or the blades spread to make electrical contact in the socket. What's the problem here? Bad plug, bad socket or air conditioner pulling too much juice for either plug or socket?

So we had our first real hot weekend this year and I'm over at the GF's place. She wants to turn on her provided-with-the-apartment window mounted air conditioner but says she's afraid because last year when she used it, she had to wiggle the plug in the socket before the air conditioner would turn on, and that the plug sparked and made a burning smell a couple of times when she used it.

I took a close look at the plug: It's a solid, molded to the wire, regular 3 connector plug with 2 blades and a ground prong. One of the blades looked charred and smoked instead of the normal gold/bronze color and hade some melted plastic around where the blade entered the plug.

I figured the first step had to be to replace the plug, so I bought a replacement plug rated for 15A/125V, cut the old plug off and wired the new one in, keeping the wire to prong orientation the same on the new plug as on the old plug.

We plugged the new plug into the receptacle, but the air conditioner wouldn't turn on. I wiggled the plug a bit and the air conditioner ran for just a second and then shut off.

I pulled the plug out, spread the blades and put it back in. Now the air conditioner would run constantly. After letting it run for a few minutes, I pulled the plug out and felt the blades. OUCH, the same blade that was burned on the old plug was now hot to the touch on the new plug.

So now what? I believe if we run the air conditioner the new plug will eventually burn up too. Is something wrong with the plug, the socket (bad contacts in the wall receptacle?), or has something gone wrong with the air conditioner that it is now drawing too much current for either plug or socket?
posted by de void to Home & Garden (7 answers total)
 
Response by poster: (Sorry, this in in the NE United States, residential 3 phase 110V AC power)
posted by de void at 1:53 PM on June 7, 2010


Sounds like the socket needs replacing if you need to wiggle the plug to make contact. Also, residential power in the US is single phase, at least in your house.
posted by 6550 at 2:04 PM on June 7, 2010


Best answer: The outlet is definitely bad. It's not making good contact which is causing arcing and heating of the plug and blades.

Since this sounds like the landlord's issue to repair, make sure whoever does the work knows the history as they will probably want to check the wiring and the circuit breaker/fuse box as well.
posted by tommasz at 2:16 PM on June 7, 2010


My guess is that something's arcing inside the outlet, or you're somehow drawing way too much current without tripping a circuit breaker. Find the corresponding breaker, turn it off, and call an electrician. That outlet's probably not safe, even without the AC plugged in.

If you don't know enough to diagnose the problem, then you don't know enough to fix it safely.
posted by schmod at 2:18 PM on June 7, 2010 [1 favorite]


If the plug is getting hot, then the outlet's getting hot too, which is one way to start a house fire. Stop using this outlet ASAP and get the landlord to fix it right away.
posted by zippy at 3:34 PM on June 7, 2010


Bad outlet. As others have said, it's dangerous and can set the house on fire, don't continue to use the AC until it gets fixed. Any sane landlord will jump through the ceiling to fix this (see "house on fire," above).

For that matter, if you put the replacement plug on yourself, have it looked at by the same electrician that comes to replace your outlet. (That goes double if you have never encountered the phrase "gas-tight fitting" w/r/t electrical work -- easy to have arcing inside a spliced-on plug if your fittings aren't right.)
posted by range at 6:51 PM on June 7, 2010


The outlet is bad, either loose or corroded. It is not your outlet (nor your air conditioner, nor your plug). Don't repair other people's stuff. Since you performed an unlicensed, unapproved repair you are now potentially liable for any problems which may of course include burning down the apartment. (I get it, you were trying to just not make waves about it. But you could make an issue for the next tenant, too--and the landlord may have wished to handle it differently--like, legally).

Call the landlord. Don't use the outlet. It's (probably) [1] safe if you don't plug anything into it. Do please disclose everything to the landlord, including your replacement of the plug for which you want to apologize and say something along the lines of "I was trying to not have to bug you about it". I wouldn't try to lie about something like this, personally.

Is it going to cause a fire? Maybe. I don't know the odds, a lot of that stuff is designed not to burn easily. Probably not, if I had to guess. But why guess?

If it were my house, I'd replace the outlet and inspect the wiring behind the outlet as I was doing it. Which leads me to:

[1] I had a weird problem where some outlets were getting low power, like a brownout. Figured out it was half of a circuit, pulled the switch where everything seemed to start and discovered a crimped connector from the original house construction, blackened and crispy. It made me consider how easily a fire could start with little warning, and gave me renewed incentive not to cut corners in my own wiring (dont' stuff too much cable in a box, don't nick the conductors, etc.).
posted by RikiTikiTavi at 8:56 AM on June 8, 2010


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