Under certain conditions the ability of a regulator to properly regulate fuel gas pressure can be affected. If a regulator problem occurs that sends high pressure gas downstream, gas-fired equipment and system components can potentially fail, which may result in a fire or explosion. This study describes the basic construction and operation of a lever-style service regulator, the type commonly used on residential and light commercial gas systems. Then, considering the mechanics of how regulators work, problematic conditions that can produce higher than normal outlet pressures are discussed and experimentally demonstrated. These examples are then discussed with regard to actual overpressure failures observed by the authors.