Lost a leg
By Josh Simons on May 27, 2005
We lost power at home during the recent nor'easter here in the Boston area. But it's a strange sort of power outage so I thought I'd post some details.
We lost part of our 3-wire, single-phase service about 36 hours ago (and counting--service not expected to be restored till late Saturday evening.) I can't find consistent terminology to describe what we lost. Is it a phase? A pole? A leg? Normal residential electrical services comes to the house on three wires--two hot and one neutral. We've lost connectivity on one hot line. Which means we have 120 volts in parts of the house, no 120 in other parts and no 240 volt service at all.
The outage started with a large spray of orange sparks in the yard from the general direction of our electric service connection point. At first I was quite concerned because I'd never seen a partial outage before and was worried we had a dangerous situation. I was also mystified because none of our breakers had tripped.
I talked to my friend Jamie (after trying to reach two electricians and the electric company) and by correlating what was and was not working with the layout of the distribution panels in the basement, we deduced that I'd lost a hot wire. Here's how to tell.
In the US, residential distribution panels are laid out as shown below. Again, "phase" means phase/leg/pole.
I could see that we'd lost power on every other circuit, which was strong evidence that I'd lost one hot wire. To be safe, I switched off all of those breakers and switched off all 220 circuits. For a nice explanation of distribution panel layouts check out Answers.Com.
We've had our electrician out and he verified that half of our service is missing at the meter and that there was no damage between the meter and the service connection point. So now we wait at the bottom of NSTAR's repair list since only a single home is affected and we do have partial power. As outages go, this one is very civilized--our heat works, the computers are up, and I can run an extension cord to power anything I really need.
As an aside, yes, I did mention heat above. It's been in the 40s all week, 30s with the wind chill. Not a very welcoming Spring so far. This robin was in our backyard yesterday, with what I imagine to be a somewhat forlorn look about the weather.