>> Under normal conditions, stringing cat5 a short distance between 2 houses on >> the same distribution transformer would be fine. Under abnormal conditions >> expect trouble. Plan for the abnormal conditions. > >Wayne, > >How much of your work was "normal conditions" ? That's a bit of a moot question - if you're working 'faults' then abnormal conditions is what you see all the time. A better question may be "out of a hundred houses, how many will have a serious problem regarding electricial supply in a one year period?" Not many. Working under normal conditions at the moment, seen two abnormals in the last month - one was a burnt out mains cable where it terminated at the isolator on the meterboard, the other when working on a switchboard with old cableing with the bare earth wires and seeing enough difference in potential between the earth wires to cause little arcs where they touched. >How many of the abnormal conditions could not have been foreseen ? I would say 99% of abnormal conditions can be foreseen, and the way they can be foreseen would be to figure out all the things that can go wrong: cars running into poles, trees falling through power lines, snow snapping lines, high wind banging lines together* etc, etc. The problem is that such conditions are statistically unlikely and so are not really taken into consideration. And then they happen. Wayne * I remember one time when it was a bit windy and the power to the whole town on Amberley kept going out - got sent up to check it out - had a look at the Amberley end, looked ok, drove up to Waipara, looked ok. So I say to the guy I'm with, "Shall we follow the lines across country?" He says, "Nup, we'll sit here for a bit," and pulls out the paper and starts reading it. Couple of minutes later there's this enormous ZAAAP! and the sky to the right lights up. "There it is," he says. The wind was blowing the 33kv line up into the earthing conductor that was strung along the top to attract lightning away from the lines. ------------------------------------------------------------------- To remove yourself from this list, email nzlug-request@linux.net.nz with "unsubscribe" in the body of the message.
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