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I have two recently dead tower fans. The first, I've had for over 6 months, no problems. Recently, I moved it to a new room an plugged it into a different outlet. It died within a day: it seems to be just the main motor, the controls still work as does the separate motor for swiveling the fan. Took it apart to look for anything obvious, tried to run it with the fan blades off of the motor but no go. So I bought a new one, different brand and model but same basic setup. Plugged it into same outlet, died within a day. Is it possible that there's something in the wiring of the outlet that kills the fans' motors? I've plugged a humidifier and lamp into the same outlet with no problems. One other factor that may be related is it's a 20A outlet with the T-shape (probably for AC as it's near an AC sleeve).

TLDR: two fans motors broke (controls still work) after being plugged into same 20A outlet (not at the same time). One six months old, one brand new. Curious if something might be wrong with the outlet and if so what I can do to test or fix it.

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Oh yes, it happens all the time. It is called a Lost Neutral.

The fix 99% of the time is to call the power company on their "report outage" number and get them to fix a problem out on the pole. They should do this for free.

Almost all residential power (except half of the Philippines) is delivered as 2 or 3 poles/phases with neutral in the middle. For instance Euro power is 400V "wye" with neutral in center of triangle and most loads connected corner to neutral. Most North American power is 240V split-phase with neutral in the middle, so 120V hot-neutral.

If something fails in the neutral wire, the neutral is no longer forced to the middle. It ends up "floating" -- think of it as a "tug of war", with all the loads on any given "leg" working together to pull their "rope" (pull being current draw).

So neutral is pulled toward the leg with the heavier draw, reducing voltage on that leg and increasing it on other leg(s). This last bit is the problem. Appliances on the lesser-loaded leg will see excessive voltages which will do damage.

"But surely I would notice this right away, I would be aware of low/high voltage!" How exactly? That's the trouble, this problem is insidious. You don't know you have it for potentially weeks or months. This is made much worse by adoption of LED lights (whose switching supplies tolerate a wide voltage range) and modern electronics again with multi-voltage world power supplies. In the days of incandescents, half your bulbs would've popped, and you'd know you had a problem!

Also, the problem isn't absolute; neutral will still be pulled back somewhat toward center by a weak, high-impedance "alternate route": through your neutral-ground equipotential bond to your grounding electrodes, to actual earth (which is made of dirt so not the most stellar conductor), to the transformer's grounding electrode to its eq-bond. So this may "get you by" except when a big single-phase load kicks in.

Once my sweetie said "I'm sorry, the toaster has been really slow all week". WTH??? Toasters only have one speed! I ran and grabbed my meter, 94V (should be 120V). Checked other locations, found 146V. Whoops! Then she said "Yeah, 2 neighbors (on that other leg) fried appliances last week". Got the electrician, we popped the cover off the panel, top of the main breaker was the same way. Power company was out an hour later (on a Sunday) with a bucket truck, grabbed the neutral and waggled it back and forth to show me it wasn't even attached.

Anyway, the cure to a Lost Neutral is to call the power company ASAP. Now, they can happen elsewhere - like in your panel or locally within a multi-wire branch circuit. But 98% of the time it's outdoors in the power company's bailiwick, because that's where the weather is. That goes to 100% if you're in places that only give each house a single phase.

A lost neutral is a bona-fide outage and you should use the power company's emergency number for reporting outages. You should turn off all your single-phase loads at once to protect them.

Some power company phone operators will try to "screen" your call to intercept stupid-user errors; they will ask stupid questions like "Do your lights work?" And you have to give them the correct stupid answer "no"* to get them to roll the truck.


* Don't go so far as to mention they're off because you cut the breaker off to protect them.

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  • \$\begingroup\$ Maybe your peasant toaster only has one speed! Who'd you call anyways? The power company through regular channels? Or what? \$\endgroup\$
    – DKNguyen
    Commented May 22, 2020 at 19:23
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    \$\begingroup\$ The power company on the phone number they provide to report outages. A lost neutral is an outage. Sometimes you have to BS your way past dullard phone people who are trying to troubleshoot stupid-user errors; they will ask things like "Are your lights working" and you must say "no" or they will refuse to roll the truck. \$\endgroup\$ Commented May 22, 2020 at 19:35
  • \$\begingroup\$ Thanks! I've reached out to my super to try to get an electrician here. The power company basically said it's not on them until a licensed electrician takes a look. \$\endgroup\$
    – Michoel
    Commented May 23, 2020 at 2:07
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    \$\begingroup\$ Your comment and answer disagree on what to tell the power company when they ask if your lights work. Yes or no? \$\endgroup\$ Commented May 23, 2020 at 6:08
  • \$\begingroup\$ Once the power company repairs the lost neutral, you can ask them to reimburse you for the replacement of fried appliances. \$\endgroup\$ Commented May 23, 2020 at 10:44
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Finally got it looked at - turns out the outlet is 220V. There are no special markings on it (aside from the T-shape marking it as a 20A outlet) and all rest of the apartment is 110V (standard here in the US). Guess it's always worth testing unfamiliar outlets.

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