anyone fixing a clock radio in the 60's learned about HAZARDOUS VOLTAGES straight up as mandatory part of the experience, but in retrospect, how in the hell did anyone survive the DIY learning curve before 13.8 volts DC and three-prong power cords were invented?
Sadly, some did not survive it (electrocutions) in post WW2 period (1945-1960s).
This led to the National Electrical Code (NEC) changes in 1962 and 1970 for Safety Ground (addition of green, third wire), and further changes over past 40 years such as Ground Fault Circuit Protection (GFCI).
The electrocutions due to installation of metallic vertical CB base antennas during 1970s CB craze, led the Reagan Administration (1982-1983) to sign the Consumer Product Safety Standard,
Title 16, Part 1204, Safety for Omnidirectional CB Base Station Antennas.http://law.justia.com/cfr/title16/16-18.104.22.168.35.html