Modifying a simple shock box diagram.

[Audioguru]

Hey guys, few days ago (thanks giving day) we had an accident with this thing......
I just concluded how this machine can not kill you.

Your nephew who was electrocuted was young and strong. But the electrodes in each hand places the heart directly in the electricity path. The electrocution caused your nephew to have very tight arm muscles and can cause a very tight heart muscle (a stopped heart) for someone who is not able to let go or who has a weak heart.

 

[D.A.(Tony)Stewart]

When they use paddles on the chest to restart the heart, it is rated in Joules. They use miniature paddles when doing open heart surgery to stop the heart, where it only takes low voltage and low current and repeat to start the heart.

Muscles are contracted by the intensity and repetition rate of electro-chemical pulses. So uncontrollable muscular excitation happens with this stimulation.

 

[Venkadesh_M]

i afraid at the beginning..

 

[BradtheRad]

I'm sure many of us were getting mixed feelings as we've watched this thread.

I must admit I've done some dangerous things around electricity. Serious mishaps could have occured. However none did.

Your nephew was lucky this time.

The shock box is not too different from arcade machines which once could be seen in amusement parks. They delivered electric shocks for fun. You turned the dial and the shocks grew in intensity.

Now they can be seen in museums. I don't remember that I ever tried one.

Amusement park machines have the tendency to be hard to beat, so I can believe the shocks grew close to the limit of human endurance.

Notice the knobs on the photograph below. They appear to be too large to grip. So people's hands could not get muscle-locked around them.

From the write-up:

"The machines remained in common use until the 1960's when the apparent danger of such machines to people with pace makers or other medical concerns was noted."

https://www.pinballhistory.com/arcade1.html