Well, it was the plate connection of the final stage of a 30 MW radar set, so a few amps, anyway. I did not present a direct path to ground through my truck, only between my wrist and elbow; and at that, there was sufficient power to throw me 30' and knock me out for 5 minutes. I don't know if my heart stopped, but the Chief ET was willing to break my sternum to make sure it was pumping.
This was the early 1970's, like '71, and we had all just been through CPR training. The Navy was just starting to be aware that not all enlisted personnel were morons studying to be idiots. Most of the ETs on my ship had at least 2 years of college and several of them had EE degrees. The officers were mostly history and poly-sci majors.
Anyway, the Chief was going to use his CPR training to restart my heart. By the time the Hospitalman got there I was sitting up and staring at my arm. I spent a week in sick bay taking it easy, but it was a good month or two before my arm worked right again.