A week into my new job I was in the server room with an old hand about to retire, who decided to pull out an old router sitting doing nothing. Immediately upon holding the device up, the whole network crashed! Our boss rushed in all hands and swear words, the phones were all ringing and this old network guy is standing there with a small router two cables looking sheepish and stating "but it wasn't connected". The boss just shouted put it back. On further investigation it transpired that when removing the old piece of kit, he had stood on the 4 way adapter switch powering the network routers, thus turning them off. Lesson learned - never leave a 4 way power adapter lying on the floor where someone can stand on the off button