Back in the 1960's, I was an Electric Traction Electrician with the Pennsylvania Railroad, working out of Penn Station, Newark NJ. We handled maintenance and repair for the overhead wire between LIRR/Pennsy Sunnyside Yard and Langhorn, PA.
Signal was 6600V, Catenary was 11000V and transmission was 66000V. Third rail was 440VDC, no safety covers in the yards. Worked in tunnels under the Hudson and East Rivers, and on the Newark Bay Bridge, 495ft up. Once you get more than 30ft up, it's all potentially lethal.
From there, I became an 1141 Engineer Electrician, USMC. All varieties of power distribution wiring and pole line construction, with generator operation and maintenance from 5KW beach illumination to 100KW Stationary Cummins. Worked on down to wiring individual hooches, mess halls, shops and the 3rd MarDiv HQ compound. My own facility was four 60KW trailer mounted generator sets running in tandem at 11th Engr. Bn. HQ in Dong Ha. Voltages up to 440VAC, plus 600Hz Commo power generation. There were 22 of us and we were responsible for much of the power in Northern I Corps, from Cua Viet to Khe Sanh.
Left the Corps in '68, and never worked on power again, I was 21
Greg