XPost: sci.electronics.design   
   From: burrynulnulfour@ppllaanneett.nnll   
      
   On 25-8-2018 9:32, Terry Pinnell wrote:   
   > John Larkin  wrote:   
   >   
   >> On Thu, 23 Aug 2018 22:52:26 -0700 (PDT), terrypingm@gmail.com wrote:   
   >>   
   >>> Thanks all, mains leakage sounds the culprit. I’ll get on it today. It’s a   
   long run, with an intermediate outdooor mains socket, then a (supposedly)   
   waterproof case with the relay.   
   >>>   
   >>> Terry, East Grinstead, UK   
   >>   
   >> Maybe something underground is full of water or ants or something.   
   >> Possibly the wire insulation got nicked.   
   >>   
   >> There are some fun instrumentation possibilities, like probing the   
   >> soil at the surface and measuring/listening for AC potentials.   
   >>   
   >> A map of the surface potentials of some chunk of land, color coded by   
   >> frequency, would be fun.   
   >>   
   >> We were on the roof yesterday and speculated how cool it would be if   
   >> we could see RF, all the microwaves and cell phones and wifis and   
   >> transmitters. That's not possible. But a surface potential map is.   
   >   
   > To my surprise the mains cabling seemed OK, giving readings outside my   
   > DMM's 200Mohm at various points.   
   >   
   > A side issue arose has me puzzled. I found about 1V DC across a twisted   
   > pair cable, disconnected at both ends, buried in several places. How   
   > does that come about? Even the short section I've cut out, with gaffer   
   > tape around connector blocks, has about 0.5V DC.   
   >   
   > Terry, East Grinstead, UK   
   >   
   Jou just re-invented the battery, two different metals with a bit of   
   groundwater.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)