I had a close encounter with an angle grinder in the past week.
I needed to change from a cutting disc to a wire brush, so I turned of the mains power at the wall and took off the cutting disc an attached the brush.
So far so good, but when I reached out to turn the power on at the wall, the grinder started up.
As I was holding the grinder quite lightly in my left hand, due to the torque reaction it jumped out of my hand and fell at my feet and the wire brush started grabbing at the legs of my overalls.
Luckily it did not grab tightly, and as my right hand was next to the mains switch I was able to kill the power very quickly.
So how did this come about?
As I was handling the grinder in the course of changing the disc/brush I had operated the switch on the grinder to the on position. So as soon as mains power was applied, it burst into life.
The switch on the grinder ((Bosch) is either OFF or locked in the ON position.
Lessons learned:
Always switch off power at the wall when changing discs.
Before switching on power at the wall, check the switch on the tool.
JimB