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High-tension mains

Volts jolt, but mils* kill
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In the UK, the 240 volt 13 amp ring main was introduced to alleviate the post-WW2 copper shortage, and replaced the earlier, more copper-wasteful star system. Now, copper is in ever shorter supply, so to use less of it in houses, I propose an increase in household voltage to at least 1000 volts, with a corresponding decrease in current (V= IR, remember) and hence reduced conductor weight.
* "mils" here refer to "milliamps".
coprocephalous, Aug 18 2005

The Skin Effect Myth http://www.absolute...t/te/tesla_coil.htm
Scroll halfway down [ldischler, Aug 19 2005]

Copper and aluminum in high tension lines http://www.key-to-m....com/Article116.htm
[ldischler, Aug 19 2005]

[link]






       What about the copper used in the step-down transformer behind every wall socket?
wagster, Aug 18 2005
  

       Damn you [wags] I was hoping for some more posts before the fatal flaw was spotted. Of course, no transformers are involved, we simply buy new appliances, which has obvious benefits for both the recycling and manufacturing industries. [EDIT] Thinking further, to improve safety, we'd probably want to raise the transmission frequency to a few MHz, to improve the skin-effect in case anyone touched a bare conductor.
coprocephalous, Aug 18 2005
  

       What would that do - surely it would still kill you?
wagster, Aug 18 2005
  

       Should help keep it away from the heart.
coprocephalous, Aug 18 2005
  

       Tension means voltage?
Texticle, Aug 18 2005
  

       Strangely enough, yes, it does.
wagster, Aug 18 2005
  

       //copper is in ever shorter supply//
Not sure that’s really the case. But if it is, you can always use aluminum. Aluminum can conduct the same amperage for half the weight of copper, and as the cost of copper is presently twice that of aluminum, the metal cost for wiring a home would be four times less with aluminum. Most high tension wire is made of aluminum for that reason.
ldischler, Aug 18 2005
  

       //Now, copper is in ever shorter supply//
Most steel produced by melting scrap contains approx 0.25% copper. The scrap comes from old white goods, automotives and so on. Liquid copper cannot easily be separated from liquid steel (only in the lab so far).
Since approx 340 million tons of steel was produced in 2004, by melting scrap, it is interesting that 850,000t of copper was locked into steel products because of the inability to separate it.
Ling, Aug 19 2005
  

       [ldischler],   

       Al is indeed an excellent conductor, but has thermal expansion characteristics that make it unsuitable for most domestic wiring applications.   

       I remember helping my dad rewire a summer cottage with Al wiring, and later discovering the potential fire hazard caused by the repeated dimensional expansion at outlets.   

       Even regular temperature excursions (Summer to Winter) can cause loose connections = high resistance = ohmic heating = fire hazard. I haven't seen Al wiring in local shops for 40 years.   

       Cu is also more ductile - can withstand more flexing without breaking. Al wiring suffers from vibration aging, and can break more readily from nicks and bending during installation.
csea, Aug 19 2005
  

       Aluminium cabling is indeed used in the high tension distribution network, but this is probably more a weight consideration - aluminium is only a third as dense as copper, though its conductivity is slightly poorer. Lighter yet would be sodium wiring, which is nearly three times less dense than even aluminium. Though the weight of the insulation would probably more than compensate...might work in the Atacama.
coprocephalous, Aug 19 2005
  

       Aluminium oxide is also a very good insulator...   

       //death level of current is between 3-7 milliamps//
It depends on how long you hold on to it, as well. If you look around, there are current vs time graphs for fibrillation. I have previously posted a link somewhere else: dimmer switches in bathrooms?
Ling, Aug 19 2005
  

       //Aluminium oxide is also a very good insulator//...but is easily removed by rubbing on a little mercury.
//death level of current is between 3-7 milliamps// Fibrillation can occur with as little as 1 microamp applied directly to the heart.
coprocephalous, Aug 19 2005
  

       (I thought it's the amps that clamps) Too much slack - pull the cable tighter
Dub, Jun 13 2007
  
      
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