I've read that the new regs stipulate that the old fashioned junction boxes (ie without strain relief clamps) must be attached to something, like a joist. Why?
Now, I can understand that one might be worried about live wires if you pulled a cable and it came free from the box. But surely, this is [b]more[/b] likely to happen if the box is fixed than if it can move about?
Furthermore, if you were to pull on a cable that is connected to a floating box with cable clamps, you are again [b]more[/b] likely to transfer that pull onto another cable. The result of this would be to run the risk of any cable coming free somewhere else, with the problem of then having to track that distant point down.
I can imagine that a frequently moving cable might cause a terminal screw to work loose, which is obviously not a good thing to happen, but what are the chances? After all, junction boxes are not usually accessible to inquisitive fingers. Besides, any flexing is just as likely to cause the copper conductors to fracture as work a terminal screw loose.
So, what am I missing? What is the reason for this regulation?[/b]