If you want to stop burglars from breaking into your house, you might not want to use pipe bombs. You may be the one who gets caught in your own booby trap:

A man tired of burglars nearly blew off his hand when bomb-like devices he set around his house exploded in his presence instead, authorities said.
[…]
The neighbor, Patrick Struble, said the explosives were “like a pipe bomb. He accidentally triggered it, and it almost blew his hand off.”
[…]
“Anything that goes `bang’ is illegal,” police Lt. Bruce Ferguson said. “I can’t think of any (legal) reason why someone would be making a bomb.”

(via)