one of the techs i work with has been hit TWICE by lightning, and he's ok. however there was a tech in our shop a few years ago that was killed instantly by the charge in the capacitor in a microwave oven. personally i can't count how many times i've been bit by line voltage or zapped by the charge on a CRT, and i did once (and only once) get popped hand to hand by 300Vdc on an antique tube radio at the age of 10. that's when i learned the one hand rule (and also that speaker frames on those old radios were at B+ potential). i have also been bit by 12Vdc batteries (in damp weather, hand to elbow). so there are a lot of factors, many of them controllable, and a few of them random, which determine how dangerous a particular shock incident is. with normal safety precautions, getting zapped in the first place should be rare. with a well planned safety procedure, it should be almost nonexistent. somebody said above that "it's the volts that jolts and the mils that kills" but it's also Ohm's Law that determines how many volts it takes to make those mils, and what path they take. but your worst enemy is your own carelessness, and occasionally lack of information. you may not know that the heat sink on the primary side of that switching supply is live, because your eyes see a large exposed piece of aluminum and your brain says it's grounded, so you go to touch it to see if the transistor is overheating. well, bucky, it's NOT grounded after all. it's a painful lesson to learn, but you won't try it again, and you will be more suspicious of large exposed heat sinks from now on. there are even audio amplifiers where the heat sinks are at the output transistor rail voltages (pioneer made some receivers like that a few years ago. the heat sinks were the large ones like the ones that they still use inside their receivers, but were mounted on plastic insulators, and all of the NPN output devices were mounted on one heat sink and the PNP devices on the other. this allowed the use of heat sink grease without mica or sil-pad insulators, but it was a very large safety hazard (especially because they were not marked as being live). getting yourself across a 120V DC (+/-60V rails) potential, especially when it's stored on 10,000uF caps can be very painful.