(In response to a Problem Map to shake cables when a grenade goes off near them)
Run the bsp and toss a grenade into the enclosure. The blast will shake the cable.
An invisible func_physbox in the enclosure takes damage from a nearby explosion. The physbox trigger "OnDamaged" restores its own health and triggers an invisible func_movelinear parented to the move_rope entity at one end of the cable. The cable shakes, simulating a response to the force of the explosion.