On the episode of I Love Lucy, I can't remember which one, when the light fell on the coffee table. If you look carefully, when the light almost touches the table, the table cracks in half. So the table was already broken before the light fell. Old table....I think not.
I'm not trying to be rude or anything but are you sure that you saw it on I Love Lucy? I've seen that Nick at Night rewind and it's on Bewitched. Remember when she does that little thing with her nose and then the light falls and the table breaks right before the light hits it? It wasn't on I Love Lucy.
This episode was not on "I Love Lucy", it was on one of the first black and white episodes of "Bewitched". Samantha makes the light fall onto the table. I've never seen this happen on "I Love Lucy", so I think you got the two mixed up.