From: CFKinsey@military.org.jp   
      
   On Sun, 23 Feb 2020 19:57:08 -0000, default  wrote:   
      
   > On Sun, 23 Feb 2020 18:30:55 -0000, "Commander Kinsey"   
   >  wrote:   
   >   
   >> On Sun, 23 Feb 2020 13:15:28 -0000, default  wrote:   
   >>   
   >>> On Sat, 22 Feb 2020 20:39:19 -0000, "Commander Kinsey"   
   >>>  wrote:   
   >>>   
   >>>> On Sat, 22 Feb 2020 05:50:10 -0000, Jasen Betts  wrote:   
   >>>>   
   >>>>> On 2020-02-21, Commander Kinsey  wrote:   
   >>>>>> My pet parrot has a habit of chewing wires but never got a shock. I   
   >>>>>> tested her feet with a multimeter and it was over 20Mohms. My own dry   
   >>>>>> finger is 1Mohm. Are they safe from shocks due to scaly feet?   
   >>>>>   
   >>>>> for useful measurements at such high resistances you really need to use   
   >>>>> an insulation tester. expect some discomfort.   
   >>>>   
   >>>> It's over 20MOhms, that's good enough for me.   
   >>>   
   >>> I don't think you can count on that.  The 9V battery in a multi tester   
   >>> may not be enough to form the current paths in the material being   
   >>> tested.   
   >>   
   >> Ah, that's why they use those criminally damaging testers for electrical   
   safety tests.  The ones that can actually destroy computer equipment.   
   >   
   > Something similar seems to go on with measuring very low ohms too.  A   
   > substantial current may be necessary to accurately measure the   
   > resistance.   
      
   Is that due to the lack of having a sensitive enough voltmeter to measure the   
   drop?  Or do conductors actually change resistance with current?  I thought   
   that only happened at really high temperature, like with lightbulb filaments.   
      
   > One place I worked had an ancient mirrored galvanometer   
   > in an apparatus that dated to the last century - but it was the gold   
   > standard when it came to accuracy at low ohms.  Four leads to test too   
   > - two for current and two for voltage drop across the R under test.   
   >>   
   >>> A high enough potential, and wood, drywall, carpeting, some plastics,   
   >>> etc., may be good conductors.  (things you learn playing with Tesla   
   >>> coils)   
   >>   
   >> Not sure how I can perform this test then.  I don't want 240V anywhere near   
   her foot for testing.   
   >   
   > Just keep the bird away from the voltage?  A little hot sauce on the   
   > wire insulation?   
      
   Never thought of adding something disgusting.  Mind you, I'd have to pick   
   something that wouldn't poison her.  Probably easier to put something   
   physically in the way of the wires.   
      
   >>> And you shouldn't discount mitigating circumstances if safety is   
   >>> involved.  I was working on my boat, hands covered with salt-water and   
   >>> figured I'd have no problem with 12V, yet touching the battery leads   
   >>> reminded me of every little cut, abrasion, torn cuticle, etc., on my   
   >>> hands.  Not lethal maybe, but disagreeable.   
   >>   
   >> I doubt it was even possible to harm you, even a 9V battery on your tongue   
   just stings.  Mind you if you're up a ladder anything that gives you a fright   
   can make you fall off.  I was painting my neighbour's eaves once and his   
   stupid wife tried to have    
   a bloody conversation with me from below.  It was the only time I've used   
   rather strong swearwords at her.  Her husband found it amusing.   
   >   
   > The salt water and battery thing wasn't dangerous since there needs to   
   > be sufficient current through a vital organ.  (the Navy said 100   
   > milliamps - but not how they arrived at that figure)  It was   
   > disagreeable enough to make it hard to work on the system.   
      
   I heard something I believe is a myth, that someone in the army gave himself a   
   heart attack from a multimeter on resistance mode by holding each end with a   
   cut finger.  No way there's many milliamps from those things.  I think the   
   accepted amount for    
   death is somewhere around what you said the Navy said (hence breakers trip at   
   30 or 50mA).   
      
   >>> I'm using one of those so-called space blankets (aluminized polyester   
   >>> film) to shield the light emanating from a indoor hydroponic planter.   
   >>> With all the timers, pumps, lights, and fans, it seemed like a good   
   >>> idea to check the conductivity.  One side is an insulator the other   
   >>> reads zero ohms everywhere I checked, even 5 feet apart.  The stuff   
   >>> isn't totally light proof it just attenuates the light ~80%, so I know   
   >>> the aluminum coating can't be very thick.   
   >>   
   >> One day that will fall down and short something and cause a fire, I'd be   
   careful if I were you.   
   >   
   > The potential is there.  The lights use a current limiter, but the   
   > open circuit voltage is 80 VDC.  Current limiting (300 ma) and the   
   > voltage is 30 volts or so.  The pumps are 120 V submersible types and   
   > the prime danger IMO.  There is a GFI and 5 amp circuit breaker built   
   > in too.   
      
   You probably don't need much current to set fire to that blanket.  Is it   
   flammable?   
      
   > It weighs 50 pounds or so with a  large footprint and low center of   
   > gravity,   
      
   My house still has fuses.  I detest nuisance trips.   
      
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