I went through a ceiling on my first day as a fresh faced 16 year old apprentice.
Fixing a 3 metre rad on my own,lifted one end onto the brackets,went to the other end and lifted,of course it came off the bracket,and I was wearing trainers. 2 weeks off!
I was working on a big heating job in a nursing home,using the existing,big column radiators. The new boilers were fired up,but a few of the rads wouldn't get hot "go round and bleed them all" I was told. I did the first few and there was lots of air,it was taking ages to bleed each one. I got to a particularly large rad in the hallway and I thought I'd speed things up by undoing the 3/4 plug in the other end,just enough to let a bit of air out. I very carefully turned the plug and air was coming out at a steady rate. I turned around to pick up a cloth and the plug shot out of the rad and hit the other side of the hall,followed by the glug,glug of very hot water that was making a bid for freedom. In my panic I put my hand over the hole to stop the water from spraying the recently painted wall and managed to hold on for about 20 seconds before getting scalded and letting go. I had to go to A+E for the burn and got hammered from everyone on site for a couple of weeks. Character building I suppose!
One more,but not mine. We were in an accommodation block in the Commando training centre, we'd fitted the 50mm copper water main and had air pressure tested everything with Nitrogen bottles. the water was switched on and everything was fine for half an hour, at which point the Bakers Blue flux finally let go on a tee where one of the guys had forgotten to solder. It's quite a sight to see a 50mm water main going full bore! He'd been told to use yorkshire flux too!