From: peter2@hipson.net   
      
   On Tue, 09 Mar 2010 06:55:17 +0000, Tim Watts  wrote:   
      
   >Jon    
   >  wibbled on Tuesday 09 March 2010 06:41   
   >   
   >> All I need is a dpdt knife switch.  If I was cheap I'd get some copper and   
   >> make one myself.   
   >>   
   >> I just bought an economical manual dpdt transfer switch rated for 100a at   
   >> 240vac.  I might have to have the electric company disconnect service so I   
   >> can wire it in.   
   >>   
   >> Don't tell me now I did something wrong.  What?   
   >>   
   >   
   >Don't you need 3p (two lives and a neutral)?   
      
   Never switch neutral.   
      
   >   
   >Have you found out how you need to handle the ground/earth connection? Here,   
   >in the event of a power failure,   
      
   See above...   
      
   >the utility earth cannot be trusted,   
      
   You're required to have ground on your premises at the entrypoint.   
   Typically three ground rods.   
      
   >so for   
   >a generator hookup, one needs a local earth rod or rods bonded to the   
   >neutral of the generator.   
      
   Not just generator, but all service. And that's why you never switch   
   neutral.   
      
   >As the earth loop fault impedance is now too high   
   >(typically 100+ Ohms for earth rod impedance) to trip a type B or C breaker   
   >in a timely manner, an RCD (you call them GFCI I think) must also be   
   >employed). What does your code say?   
      
   (Comments based on USA rules, may vary in other countries!)   
      
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