Mains operated synchronous motor clock running super fast

[HectorLooi]

This is so weird. 

It's 4:10am, I got up to use the bathroom and noticed my ancient Smith's electric table clock showed 12:25.

Then I noticed the second hand running super fast. I used my phone stopwatch to time it and it was taking 30 seconds to complete one revolution.

How can that be??? 

Synchronous motors running speed are dependent on the mains frequency. I looked at my bedside radio clock, which also depends on the AC frequency for timing, and that's showing the correct time???

Then I start to worry. Is something in my electrical system that is arcing and causing spurious mains signals?

I unplug my Smith's clock and plug it into a different wall outlet and it's running normally. Really weird.

I'm going back to sleep.... brain not working....

Goodnight!

[HectorLooi]

I found that the clock runs fast when I plug it into the socket that has a built in surge protector.

I took apart the surge protector and found that it only has 2 components inside, a gas discharge tube and a metal oxide varistor wired in series across the L and N line. Something must have failed and clamped the voltage above a certain value and affected the motor.

The clock runs fine when plugged directly to the wall socket.

[oldhippy]

You have gremlins in your home.  

[HectorLooi]

2 hours ago, oldhippy said:

You have gremlins in your home.  

Cool! I'll catch some and sell them as Christmas presents.