Posted: 9/26/2006 3:00:44 PM EDT
| Are power lines insulated? If they are, why do people get electrocuted when they touch one? If not, why not? |
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You touch, you become path to ground, you fry and you will hope you die. Ever seen a joint blown inside out and cooked? Not pretty. Yes to save weight, but also to let them cool faster. They heat up they stretch and droop. Transmission lines, neverr insulated, primary never, secondary, SOME older ones. House drops, sometimes yes and sometimes no. Underground lines are of course insulated but cannot carry the load that an overhead line can, size for size and are much more expensive to make, put in, and find problems later on. |
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I could give you the safe clearance distances for any voltage level, but I think I won't. Someone might have a beer holding moment and screw up my day. The bumper sticker someone saw is SOP. Air is actually a fairly good insulator, until you fill it with something else more conductive, like smoke, water, or a body. 
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| guy here local in cincinnati flew his ultralight into high tension lines last week, and hung for 8 hours while they de-energized the lines and then cut him down. He never made connection to ground (or another wire) while he was hanging, so aside from the retracted testicals, he was okay. |
Look at it from a cost/benefit perspective.  It is all about the money. (The  was for me, for thinking we were discussing powerlines)
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If your asking if powerlines are insulated, I'm very worried. Check this out...this is how far electricity can arc.  Link |
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There are some primary lines 2400V up to 14400V that are insulated. Specially made for tree contact, very close spacing. Brand name or common known name is Hendrix Cable. The secondary that we use (120V & 480V) is all insulated. Only the neutral wire is bare. Air is not an insulator, we use a standard for seperation of wires, that being 15" of air 18" of fiberglass 30" of wood Wood is not a very good conductor. Just try getting it wet. Course the old timers use to use a lot of wood sticked tools to do line work. And if you see any wires in the air or on the ground, do not touch regardless, call your local utility or 911 report it as a wire down. 120V can kill, not likely but it can. And those wires that carry 120V normally can become energized at higher voltages. |
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I surrender. I guess interior wiring, local distribution circuits, and 'powerlines' are the same thing. Oh, and 'volts' don't kill, amperage does. As in about 0.1A. Example - ever been tasered? Lots of volts, very low amperage. But, with power circuits, you have to keep Ohm's Law in mind. At the fault, volts are low, amps are high. Bad juju. This ignores arc formation. Plasma is, of course, really effing hot. Now I will re-institute my private rule, and cease talking about work with anyone I don't work with. (I'll make an exception for djohns6 , as he said some of the magic words. I'm sure he knows exactly what an SEL-21 is, or what any of the following numbers mean, 50, 50N, 51, 51N, 67, or acronyms SPCU, DCB, DCUB, PUTT, POTT, and, most importantly, what a reverse-looking Zone 3 is normally used for, etc. Not to mention B/U relaying, B/F relaying (yep, a type of B/U), and 87B, 87G, which usually operate an associated 86, and the normal reach of Zone 1, 2, and 3.  We could have some fun explaining Vars, skin effect, and the travelling wave thing).. |
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Just keep your tweaker in your pocket! You guys can absolutely ruin my day. OTOH, you can make life exceedingly easy, too. Timing is, after all, everything. I've been a fan of SEL for a long time. I particularly like the remote interrogation capability on the stuff we use.
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Wow! Thank you! Brother in law is a linesman. I always figured he was just exagerating about some of the big plasma balls that he has seen. |