DC Defibrillation

The U.S. Navy teaches that it takes a minimum of 30vac, .1amp to cause heart defibrillation, assuming a 300ohm body resistance. They however do not teach on the subject of heart defib. from a DC source. Since getting out of the Navy, I have been giving electrical safety training to oilfield companies, and in my classes I am teaching the hazards of DC starting circuits in motor vehicles, particularly for the shop mechanics.The average 12vdc truck battery is pushing 1000amps to the starter, so if the mechanic happens to get in series with the starter, the outcome cannot be good.My question is, does it matter what source(ac/dc) is pushing the .1 amp through the heart to kill you, and is my training correct on DC starting circuits for mechanic safety?
- David Ridgeway (age 47)
Big Lake,TX.76932

Hello David,

We are not medical doctors here so take our answers with a grain of salt. 

What I gather from , is that DC defibrillation is really not a DC current but a momentary discharge of a capacitor that has been charged up by a DC source.  The actual current is a sharp spike that resets the heart beat. 

The lethal current varies all over the map depending on the magnitude and duration. To add to the confusion the body's skin resistance also varies depending on wetness, area of contact, etc.  see   However, it would seem to me that a 12 Volt source is not particularly dangerous, unless, the mechanic's hands are wet.

For additional information on the subject visiit our web site

LeeH

(published on 02/25/2015)