JC™

The blue component is the Metal Oxide Varistor (MOV). You can see the MOV was burnt. That was caused by lightning strike. The yellow and black wires was connected to telephone line. The red and blue was connected to AC power and the green cable was connected to earth.

The capacitors that filter out interference from the AC power are called Suppression Capacitors. There are two major types of suppression / AC line filter safety capacitors; namely, type X and type Y. The purpose of these capacitors is to reduce radio frequency interference and to ensure safety from shock and fire.