An analysis of mining explosive accident reports indicates a need for clear and ample warning of approaching electrical storms to reduce injuries and/or fatalities due to lightning-induced premature detonation. During the spring and summer of 1979, six lightning warning devices were comparatively evaluated at three test sites. The devices tested were (1) flash counter, (2) corona point, (3) radioactive probe, (4) field mill, (5) azimuth and range locator, and (6) triangulation locator. The test sites were chosen to provide system evaluation under varied thunderstorm conditions. The devices were tested at San Antonio, TX; Kennedy Space Center, Cape Canaveral, FloridaL; and Langmuir Laboratory near Socorro, New Mexico. Comparitive performance evaluation is reviewed in terms of alarm reliability, false alarm, and failure to alarm probabilities. Improved lightning warning system requirements and methods of relating warning criteria to explosive hazard are discussed.