MadSci Network: Physics

Re: How might someone survive electrocution after a radio falls in his bathtub?

Date: Wed Aug 8 16:36:16 2001
Posted By: Scott Kniffin, Nuclear Engineer, Orbital Sciences Corporation
Area of science: Physics
ID: 996187793.Ph


Sorry for the delay, we've been a bit busy here at NASA the past few weeks. 

First of all, I'd like to state that under normal circumstances with a 
standard outlet, it would be quite probable that the person would die.  The 
possibilities that I came up with are as follows: 

If the radio were plugged into a ground fault current interrupt (GFCI) 
outlet, the person in question would get a bit of a nasty shock in the 
short time it takes the circuit to trip open.  But that wouldn't be very 

If the circuit that the radio is plugged into is very loaded (several other 
things are plugged into that circuit and are on and draw significant 
current) it is possible that the current spike as the radio first comes 
into contact with the water could trip the circuit breaker in the house.  
This is unlikely as most house breakers are rated for 10 or 15 amps with a 
2x over current spike capability.  

The third, and somewhat cliched, option is for the cord to fall in such a 
way as to be "grabbed" (tangled really) by the spasming victim, causing 
him/her to yank the plug from the socket.  This is at least somewhat 
realistic as electricity does affect muscle movement, the problem being 
that AC current makes the person basically contract and extend their 
muscles 60 times a second. Hence, the cord would have to tangle in the 
fingers or wrap around a toe for this to really work.  This may have a 
significant non-reality issue attached, use your judgement.  

Speaking as someone who has been shocked by bad/poorly isolated equipment 
with both 120V and 240V AC, there is an additional fact that you may want 
to consider or ignore, depending on how your plot goes.  After a nasty 
shock, a person may temporarily loose muscle control and slump.  This sets 
up a drowning possibility.  If it were the tip of an extremity, usually 
that whole limb is numb for a while, while a whole body experience would 
really be unpleasant.  After the 240V hit to just my right hand, I sat on 
the floor where I was tossed to for a good 10 minutes before I could get 
up.  (Yes this was in my more foolish youth and in total disregard for just 
about every electrical safety rule there is.)  I've since been a safety 
officer and have a much greater appreciation for the hazards present in a 
home and at work.  

Good luck and I hope this was of value.  Just don't try it at home!

Scott Kniffin
Senior Engineer, Orbital Sciences Corporation
NASA Goddard Space Flight Center
Office of Systems Safety and Mission Assurance
Radiation Effects and Analysis Group 

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