Dear PoPville – Mysterious Partial Power Outage

Photo by PoPville flickr user fromcaliw/love

Dear PoPville,

We’re ready to file this one under unexplained mysteries, but my wife and I would like to consult the PoP community first.

At 1:30, Sunday morning, we had a power interruption in our Columbia Heights row house, built in 1918. Approximately half of our outlets on either floor, ceiling fans, and other electrical fixtures were without power, while our major appliances and some other outlets and fixtures worked perfectly. We surmised that there was circuit breaker problem of some sort. Not wanting to disturb our basement tenant, we decided to leave the problem until morning. Seemingly by magic, sometime before 6:30 am, power was back to normal. (Our tenant says he didn’t touch the circuit breaker.)

So, our questions are what can cause such a power interruption, and, more to the point, is this something we need to worry about? We’re certainly not electricians, but we always thought that the electricity coming into our house is from one common source, and it’s an all-or-nothing set-up. We’ve owned the house since Nov. 2010 and this is the first time we’ve had such an experience.

Any knowledge your readers could drop would be most appreciated.


A couple of Columbia Heights residents

P.S. I don’t know whether it was related, but I saw a Pepco truck drive by our house later Sunday morning.

17 Comment

  • OP, sounds like you you have been a participant in the biggest inter-dimensional cross rip since the Tunguska blast of 1909!

    • Awesome. Will there be time travel opportunities? I have always wanted to go back to 1986 to tell John McNamara to put Dave Stapleton in as a defensive replacement in game 6 of the 1986 world series. Oh and also to buy a shit ton of apple stock.

      • Don’t you dare. The best team won that year, no question. Besides, the game was tied already, thanks to the wild pitch, when Mookie hit the grounder – momentum had swung.

        -signed, someone who agonized over that game with a game 7 ticket in his ninth grade hand. Game 7 is still in the top 10 for best days of my life.

        P.S. – in case you haven’t seen the RBI Baseball version:

        • Ha ha. That is an often forgotten detail about that series. It was either Calvin Schiraldi or Bob Stanley that threw the wild pitch. Stanley I think. He gets none of the historical blame.

    • Sweet Ghostbuster reference!

  • This same thing happened to me 2 winters ago after renovating my house and installing new electric. This happened during the ice-storm and my power was not fixed for over a week…so no heat/no spark to light the gas furnace

    There are 2 phases of power coming into you house, imagine 2 separate wires. One wire goes to one side of your panel box and one wire goes to the other side of your panel box. I believe that one phase or your power was out which would explain why some outlets and appliances were working, the working ones were on the working side of the panel box with the live power, the other side of the panel box was out.

    Sorry for the run-on. This problem should be corrected by PEPCO

  • This is pretty common, it’s a partial outage. You have three wires coming into your house, 2 hots and a neutral. if one of those “hot” wires goes down (wire down, fuse blown, etc) that would cause some outlets and all major appliances to not work. Standard 120V appliances run across one of the hot wires and the neutral, larger 240V appliances like you dryer run across all three wires. If one goes down, you lose any outlet that is wired from that wire and all 240V appliances. Sounds like Pepco just fixed the issue, but you should always call to report it if it happens again.

    • Thanks for this link! It that explains why the outlet for my refrigerator/stove and my A/C weren’t working after the derecho storm, but otherwise I did have electricity. (I think my original comment on this thread got eaten by the internet elves…)

  • Had similar experience, but it turned out that of the two service lines from the street, one had failed. Unfortunately, did not think to call Pepco first, so had to pay electrician to define that problem. Pepco ended up replacing both lines.

    Another question – a few years back I thought Pepco was moving meters outside, at their expense. Is it true that consumers would now have to pay to do this for the utility to have the convenience of an accessible meter?

    • PDleftMtP

      You’re not the only one who did that. I saw my neighbors’ lights were on (of course, they all had the same issue and I was seeing the lights that were still working), so I thought it was me and called an electrician. The two circuits into the panel explanation is correct. Depending on how your house was wired (and rewired) over time, the pattern can look completely random, but it’s one side of the panel or the other that’s out.

    • Regarding accessible meters… did you mean that Pepco was offering to move meters from the backs of houses (where they’re often fenced in and thus not easily accessible to meter readers) to alleys or something?

      I hadn’t heard anything about that, but now that Pepco is shifting to “smart meters,” presumably it won’t matter any more where the meter is physically located.

  • Yes, this is a common type of power interruption. your electric service has two poles, at different phases. Each pole powers some of your circuits, the other pole powers the rest. When one pole goes out due to a partial Pepco outage, the circuits using that pole don’t work. Like any other power outage, call Pepco.

  • After the big derecho storm at the end of June I came home to find that anything plugged into a few outlets (which I have marked in my fuse box as being on the same fuse) were off even though the electricity elsewhere in the apartment was fine. I assumed that the storm had blown a fuse to the point of needing to be replaced, so I plugged the refrigerator into an extension cord leading to the other wall and went to sleep. When I woke up, all outlets were working again! I don’t have an explanation, but apparently it’s not as weird as you or I might have initially thought (and I live in a condo).

  • Speaking of electrical – can anyone recommend a reliable master electrician? We have some issues we would like to take care of, but want to make sure we find someone who really knows these old houses. Ours was built in 1910.

  • Every house has three wires going into it, effectively +120V, 0, and -120V. Since AC power is a sinusoid cycle the plus and minus are just achieved by one being 180 degrees out of phase with the other. Most outlets are 120V, using one of the + or -120V and 0, but dryers and others have the big 240V outlets which use the +120 and -120V, the difference being the 240V that power big things. When they wire your house, they wire some circuits with the +120V & 0 and others with the -120V & 0. Since things are powered by the difference between voltages, they only see it as 120V. However if one of the 120V circuits on a block go bad, the rooms that use that wire get no power, so you will have some rooms with power and some not…and anything that is 240V will have none.

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