The US National Fire Protection Association does most of the research and code writing to address the potential for explosions of gasoline vapor. The customer fueling area, up to above the surface, normally does not have explosive concentrations of vapors, but may from time to time. Above this height, where most fuel filler necks are located, there is no expectation of an explosive concentration of gasoline vapor in normal operating conditions. Electrical equipment in the fueling area may be specially certified for use around gasoline vapors.