[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Shocking submersible pump

> I put a new Rena Flow 80 submersible pump I bought thru
>  Pet Warehouse into operation tonight.  When I put my hand
>  into the tank to re-arrange some plants I got a shock.
<snip part about feeling pain, thinks it's DC shock...>
>  Anybody know why I'm still alive?
First, it had to be an AC shock, not DC.  There's nothing to rectify the 
current from AC to DC in the pump, and it couldn't be anything else.  The 
reason you're alive is because you didn't get the full current through your 
body, and there wasn't a good ground all the way through your body.  The 
current probably went through your fingers and arms, but couldn't find a 
route across your heart.  You probably experienced what is called "leakage 
current."  That's where a small short circuit caused by a break in the 
insulation somewhere along the line or inside the unit itself allowed some of 
the line voltage to inefficiently "leak" outside the case.  To kill you, you 
need at least about 15 milliamperes of current directly across your heart, 
but probably much more.  115 VAC isn't very efficient at killing a human, 
which is why electric chairs use more like 2,000 volts, and even then 
sometimes it takes 2 or 3 shocks of 1 minute or more apiece to kill a person. 
 The typical electric chair hits you with around 2,200 volts for about 15 
seconds, and then the voltage drops to about 600 volts for another 1 or 2 
minutes.  115 VAC can kill you, but it usually takes some time across the 
circuit.  There are exceptions, of course, of people being killed from very 
short contact, and these are probably explainable that the person's heart was 
thrown into Ventricular Fibrillation, from which there is no return unless 
the Paramedics get to you fast and defibrillate you.  There are also tales of 
people having gotten across 115 VAC lines and living for up to 30 minutes 
before finally dying.  I'm not trying to say that the leakage current isn't 
life-threatening.  It can be, particularly if you're standing in a nice 
puddle of water and presenting a direct circuit to ground.  But the truth is, 
most such shocks scare you more than anything else.  By the way, you should 
thank your heart for not going into V.Fib on you.  Not every heart is so 
considerate.  Oh, and I would give that pump a fast trip to the garbage can.