A few further thoughts on this and some updated info.... .. .Assuming most defibrillators operating standards are similar and these figures could be applied to other models..... .. .360 Joules of energy delivered to a patient via chest paddles or self adhesive chest pads completes the electrical circuit of the defibrillator.. .. .But what if the patient is in contact with a part of the aircraft which isn't insulated? Dire warnings not to touch the patient during defibrillation are given during training. Surely some current could leak to earth?. .. .Assuming that the aircraft electrical systems are also connected -ve to earth would that not cause problems?. .. .As an idea of voltages and currents involved I have taken these figures from our operating manual for the machine we use.. .. .Ohms Law states Voltage = Current x Resistance or V=IxR. .. .With a patient skin resistance of 25Ohms the machine delivers 53.1A for approx 10 mSec which equals 1327.5Vdc.. .. .or,. .. .With a skin resistance of 100 Ohms the machine delivers 13.7A for 36.4 mSec which equals 1370Vdc.. .. .I appreciate that HF currents can be much higher than this,(I have several RF burns to confirm!), but the antenna is not connected to the -ve electrical system.. .. .Any further comments would be appreciated.. . . . <small>[ 07 March 2002, 14:06: Message edited by: pilotwolf ]</small>