Just a quick note to say that after returning from my vacation I had some nice fireworks when I put the power cord back into the wall socket of one of my power extensions. I pulled all cords before going on vacation. Both the wall socket and the power extension box were putting up a nice show for a second with loads of sparkles. Then came the nice smell of burned plastic.
Multiple equipment was connected to the box; a laser printer, 2 monitors, 1 PC and 1 SAM 440. Everything still seems to work....except the SAM 440. I hope it is only the PSU which has fried; I'm still waiting for a replacement to check that out.
First time I saw sparks flying at both ends of a cord (wall socket and extension box), don't know what happened :-(