Player jumping down from some height also causes this problem to occur, they break all non-local breakable objects around them without any kind of direct contact.
This problem was first noticed in public version few week after release and still present in all public and dev versions.
Setting "allowDamage false" or "enableSimulation false" on the lamp from either host or client or both doesn't help and lamp still breaks down without direct contact.
Video of the bug:
http://www.youtube.com/watch?v=twOdQaVj5lk#t=44s