How do you lose power with buried power lines?


I just moved to a new community with buried power lines which gave me a false sense of confidence before the remnants of Ian hit. No luck though – we still lost power last night for several hours. How does that happen? Am I more or less likely to have power go out, and if it does out, does it typically take the same amount of time to restore? Halp.

In: 3

Being underground could make them more likely to get damaged from flooding or storm surge. As far as repair, it can take longer. Now you have the same issue of power outage but three feet underground.

The lines underground are less likely to experience wind damage, but all the lines are not underground all the way back to the source. The lines from generating plants are almost always above ground. As are substations, etc. Your maintaining power depends on all those sections as well.

There are usually some lines above ground somewhere in the system. They are still less exposed overall than above ground systems so it should be less likely to fail in a storm and faster to fix since crews won’t have to run all over town fixing downed wires. Less failure points is always better

Power line coming out of power plants are very well protected. As are the huge high voltage line towers you see running through accessways high above ground. They are up so high to insure a falling tree can’t affect them. If they did get messed up, the outage would be major.

There will be a substation somewhere that converts high voltage to lower voltage, and shares it to multiple zones. These are almost always above ground. And are the source of many outages.

Then theres the possibility that the power line is above ground anywhere between where you live and the substation.

Generally speaking, a cable that goes underground is pretty damn safe. It sits in a place where very few things can get to it.

However, when we say “very few” it kind of suggests that it’s not entirely fool-proof, huh?

One of the first things that come to mind when we talk about stormy weather is that a cable that has been in the ground for a decade or two, may have gotten itself tangled into some tree roots. And if the storm gets to the tree, it could potentially damage the cable as the tree falls in the storm.

Another thing worth keeping in mind is that even though the cable is in a trench, and generally speaking very safe, the rest of the distribution system needs to be somewhat convenient to access over ground; the distribution cabinets and the small huts with the transformers in it, all of that stuff is overground and can totally experience what it’s like when someones carport comes flying.

Some types of stormy weather also drag a lot of water with it and floods large areas. Those cabinets and the transformer stations, they can withstand SOME flooding, but there is always a chance that the weather will win and fill the entire substation with water (or, you know, enough of it to reach whatever non-insulated power system you typically find in a substation) so that the power goes out.

There is also another aspect of it well worth to remember; power lines that bridge long distances (such as regional, state-connecting or national backbone kind of long distances) are very high voltage. So high, in fact, that there are no commercially available cable alternatives. Those power lines are ALWAYS on poles or pylons. Protected from the elements with, frankly, the cunning trick of placing them high up out of reach. But it still happens in really windy weather that perfectly well built roofs on industrial complexes take off in the wind and reach up to those power lines.

You also need to keep in mind that the weather is also a risk for some production facilities, because the weather makes some theoretical problems impossible to deal with when you can’t send out personell on the outside of the building in the storm; some producers shut down in bad weather instead of risking something even worse that may come from a malfunction in the worst kind of weather. Once producers start considering shutting down too, there may in theory be some harsh choices to make on what *consumers* to disconnect as well to balance out.

In reality, a local power company can see where the wind is blowing (so to speak) and deliberately disconnect something that would probably fail soon anyway, to protect the integrity of something that is more important to keep going. (say, disconnecting a subdivision of houses in favour of keeping a hospital powered or shutting down a closed shopping centre in favour of a pumping system that protects a subway line from flooding.)

Without knowing where you live and without having someone at your power company to ask, you are never going to find out exactly which one of all these guesses it was that disconnected you. But generally, you know, the powercompany makes money selling electricity. The would have continued to do so if they could. 🙂