One of the hazards of operating a rig with voltage across the key is sooner or later you forget that fact. I removed the safety shield over the strap-on key as I liked to adjust the contacts from time to time.
One common operating procedure was to get up early on a Saturday morning, about 3 a.m. because that's when the VKs came through on 40M and it was the best chance of working them. There was no guarantee but I did manage to work both VK and ZL as long as the received signal was 559 or better.
I did this on several occasions, until one morning I absent- mindedly reached down and started to adjust the key with it plugged it in. I got a terrible shock and it felt as if my hand had been hit with a hammer.
It left a salty taste in my mouth and from then on, I never touched the key while the plug was in the jack. It could have been fatal had I not reacted so quickly and broke the connection.
I wonder how often that happened to military personnel on operations?
The "B" Set:
At one time, the North Bay Hydro used to turn on and off the flat rate water heaters which had a frequency sensitive relay connected to the 110V line.
During peak loads they could dump all the flat rate water heaters off line and gain several hundred thousand kilowatt hours until demand dropped and the water heaters could be switched on.
The relays operated at 720Hz which was the 9th harmonic of 60Hz. I know this, since my brother worked for Hydro and eventually built them an oscillator to test the relays.
It wasn't long before the local Radio Inspector accused me of being the culprit because the "B" set contained a superegenerative receiver and he felt the "squegging" frequency, generated by the superegenerative action was doing this.
In other words the "B' set squegged at 720Hz or thereabouts. Such proved not to be the case as the power needed to turn the relays on was far above any oscillations emitted from the "B" set itself.
I breathed a sigh of relief when exonerated but it was very intimidating when I didn't even know what "squegging" meant.