Power strips can also have surge protection. Older power strips just used a metal oxide varistor (MOV) between conductors. These MOV’s are sacrificial. The MOV’s conduct when voltages exceed their ratings. The excess voltage
is dissipated as heat in the MOV. Some MOV’s were found to fail as shorts. They then generated severe heat and burned through the plastic body of the power strip, igniting nearby combustible material. Newer surge protectors
have a thermal fuse attached to the body of the MOV. If the MOV overheats the thermal fuse opens, removing the MOV from the circuit, preventing a fire.