Expert Questions Claim That St. Jude Pacemaker Was Hacked – IEEE Spectrum This is an interesting case where security researchers claimed they have found serious vulnerability in medical device and earned money when the company stock value dropped. 

Mains power loop impedance measurements

Measurement of earth loop impedance and determining the Prospective Fault Current (PFC) are critical for safety and form  integral parts of the International Electrotechnical Commission (IEC) guidelines like standard IEC 60364 (and its various national equivalent standards). The prospective short circuit current (PSCC) or available fault current or short circuit making current is the highest