sunny day greenhouse debugging
Tuesday, January 13 2015
Yesterday Ramona succeeded in bringing the articulated deer leg into the house, and she managed to secret it back on her dog bed behind the woodstove, allowing Gretchen to overlook it. By this morning, Ramona had cracked open the femur and eaten much of the marrow within. She'd also managed to stain a square foot or two of her dog bed, which Gretchen eventually saw (to her horror). Luckily, the dog bed was made of some sort of wonder material because the blood was fairly easy to clean up with just a cold damp rag (never use hot water on blood stains!).
It was another brutally cold day, with temperatures during the daytime in the mid-teens, but at least it was sunny. While Gretchen and I have mostly been content to sit by the woodstove on days like today, Ramona hasn't forgotten about the greenhouse. At some point this morning, I was wondering where she was, and when I looked down there I could see her lying on the couch in its upstairs. I later went and joined her for about twenty minutes and managed to get nearly as much sun as I had during the entire vacation in Belize.
Later I took advantage of the temporarily sun-heated greenhouse downstairs to do some more diagnostics of its shorting electrical circuit. In an ideal world, I'd have a device called a Time-domain reflectometer, which can measure the distance along a wire to a short (or less serious electrical problems). But lacking that, I was forced to use a screwdriver to open up boxes, disconnect parts of the circuit from each other, and use a multimeter to measure resistance across segments of it. I
first opened the electrical box above the door, undid the wire nut binding all the black hot wires together, and then measured for shorts between each hot wire and neutral. Doing this, I determined that the problem lay either in the next box upstream (closer to the garage and the source of the power) or somewhere upstream from there (though I'd already determined the problem lay downstream from the box where the supply cable first reaches the greenhouse). Some further testing determined the short was happening where the supply wire cable into a light box lying midway down the north wall. Though I could make the short go away by jiggling the wire, it seemed impossible to eliminate the risk of it happening in the future. So I might have to abandon that black hot wire. Fortunately, the cable containing it is 10 gauge Romex with three conductors and a ground, and one of the conductors (the red one) isn't being used. So perhaps I can use it instead, unless, of course, heat produced by the short managed to damage it as well.
As I worked, I listened to the This American Life podcast entitled Batman about a remarkable gentleman who grew up with no eyes but is able, via echolocation, to move around independently and even ride a bicycle. The gist of this episode is that people (and even rats) tend to live up to the expectations of others. A perhaps controversial version of this idea is that most of the reason the blind are considered helpless is that our society expects them to be. But if allowed to deal with their condition the way human children naturally do (including by making clicks, which, I learned, is actively discouraged in the United States), they can adapt. Indeed, imaging of the brains of blind people who use ecolocation shows that the visual cortex of their brains forms real pictures of their world.
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