San Diego’s weather is usually famously nice but when we get serious storms the weather can turn quite harsh. Last night we were getting the kind of weather one would expect in the Falkland Islands, basically 50mph wind all night long. This storm caused the most unusual power outage I’ve ever experienced. The lights in the room flickered and some of them went out.

At that moment, my son and I were using four computers (hey, I’m a computer guy) that were plugged into wall outlets. Two of these died. I was able to turn on the monitor of the work station I had been using and I was able to give it a proper shutdown. The last computer was my main server. Because the router and cable modem were also still running, I was able to log into the server with my "phone".

This was so weird I had to understand what was going on. I first tried my Kill-A-Watt meter and got nothing. I tried an electrician’s outlet tester and it showed the outlets to not be live. Of course I checked the circuit breaker and none were tripped open. Since I have a pretty splendid view I could look out over my neighborhood and see that something was very strange. Most lights were off but some were on.

With my multimeter I checked the voltage from the wall. It was about half of what it should be, between 50 to 60VAC. This is not at all correct!

outage halfpower

First is a photo I took outside my lab’s window. The other images show the outage and the low voltage condition. The dark photo is dark because that light is burning very dimly and all other lights are out; my server’s blue LED is still on.

Computer engineers worry about power outages and power surges. The interesting thing to consider from this is should you worry about your equipment’s ability to also operate with a severe under voltage? See this information on "brownouts" to learn more about potential risks.

The other thing to note is that even if an outlet tester shows that the circuit is not live it may, in fact, be somewhat live. Half a dose of normal American electricity probably won’t kill you but it may be a nasty surprise!