The second function is to help protect a circuit against high voltage transients. These are surges which originate from electrical storms or the switching of inductive loads, and it is common to use a metal oxide varistor (MOV) to divert excess current in such events. The ability of an MOV to provide continued protection throughout the life of a product may be greatly enhanced by using a line input resistor to restrict the surge current. Effectively, by sharing the surge energy between resistor and MOV, the lifetime of the latter may be extended, and a smaller MOV may be selected. Shown here, placing the resistor on the line connection side of the MOV is considered preferable.