Lights flicker across region

Same. I thought it was a normal flicker/surge/whatever. Sometimes that happens. As long as the lights come back on, I don't think anything of it.

Sunspots or somebody testing a terrorist attack on the grid.

Didn't notice it on Eagle Hill. Fair chance I was too wrapped up in catching up on The Walking Dead...which would have freaked me out a bit.

The flickering was the result of the momentary re-alignment of the electric transmission and distribution grid re-aligning itself (either manually but more probably automatically) to deal with an interruption in the way the transmission was being managed prior to the event.

Remember - electricity is unique in that it is 'used' within about one second of being generated so there isn't much time to buffer events. And that also means that the amount of generation has to be balanced exactly to the consumption at all times - there isn't a tank to store excess electricity, as with your town's drinking water.

Also, remember that the entire electric grid is interconnected - so it doesn't matter what company bills you for your town, or if your town has its own power and light company - all of us within ISO New England are on the same 'grid.' ISO NE is the regional authority that manages generation and load balancing throughout New England (parts of it anyway, including all of Mass). So one glitch (assuming it is big enough) anywhere within NE could affect us all (as it did last night).

My guess is that NStar is talking about a 'high tension' or 'high voltage' transmission line - not just a wire to someone's house. Carver has a confluence of high voltage lines where the transmission lines from the Pilgrim nuclear power plant and the transmission lines to Cape Cod all converge. So it is right in the middle of the 'electricity highway' for SE Mass. [Bellingham MA is another well known 'confluence point' - hence the reason for the concentration of gas fired electricity generating stations in Bellingham - easy access to both the natural gas pipeline network and the transmission grid. But I digress.]

If the failure of a transmission line results in a large enough 'loss of load' (blackout) or a restriction in the ability of the grid to transmit electricity, then the system is instantly thrown into imbalance (think of it as too much power, not enough consumption, in the simplistic big blackout scenario). That can result in power surges and voltage dips or spikes throughout the system - which can cause protective devices in other substations and power generating stations to 'trip out' - cascading the blackout to other areas.

My guess is that we were somewhat lucky. A similar failure of a single high voltage transmission line near Cleveland Ohio is one of the events that started the cascade of events that resulted in the New York City to Canada to Ohio blackout of 8/14/2003. Admittedly, there were other factors in that incident, including degraded / malfunctioning monitoring software and alarm systems, deferred maintenance, and human error, but the failure of high voltage transmission lines were key to the blackout.

Part of the reason why we were lucky last night could be improved computerization / automation of the grid to respond to transmission interruptions, as well as the relatively low load demands of a weekday evening in October. Had this happened at 3 PM on a 100 degree day in August, things could have been different - the flicker could have been a blackout for a bunch of us. The statement that NStar makes about 'other equipment' being able to 'handle the electricity needs' is exactly correct - for an evening in October. But that is really just because the electricity distribution system is designed (somewhat) for the peak load days (or hours or minutes).

Technical, but very interesting reading: http://energy.gov/oe/downloads/blackout-2003-final...

This paper also includes a good discussion about why New England was isolated from that August 2003 blackout - describing the safety mechanisms in place that disconnected NE from NY/PA/OH when that system started to fail.

That paper also describes why it is essential for utilities to maintain their right of way along high voltage transmission lines by clearing trees and growth - transmission lines sag when under heavy load. In the August 2003 event, many of them sagged and contacted tall trees in the rights of way that hadn't been properly cleared prior to August 2003. So we should all support the clearing of trees along high voltage transmission line rights of way - unless we want to risk major power outages.

Dave
(not an electrical engineer, nor an electrical utility employee, so take this all with a grain of salt - I could especially be wrong about my pessimistic assessment ('we were lucky') of the robustness of the transmission network here in Mass. Maybe we didn't need luck - maybe the system worked as advertised.)