Examples of effects of ash on power facilities and transmission from eruptions during historical time:
The consequences of loss of electricity supply are widespread, and many other public utilities (e.g. water supply pumps, radio and telecommunication facilities) may be inoperative for the duration of the power loss unless local backup power supplies (batteries and generators) are available.
The following table shows the general effects of ashfall on power facilities and electrical distribution systems that resulted from several historical explosive eruptions in the world.
| Volcano (Nation); Eruption year | Effects |
|---|---|
| Mount St. Helens (USA); 1980 | Insulator flashovers in areas receiving >5 mm (1/5 in) of ash, in conjunction with rain. |
| Redoubt Volcano (USA); 1989-90 | Insulator flashovers in areas receiving ash, in conjunction with rain. |
| Rabaul (Papua New Guinea); 1994 | Wire and cross arms damaged by collapsed buildings and tree breakage. |
| Ruapehu (New Zealand); 1995 | Insulator flashovers on high voltage lines receiving moist ash. |
| Ruapehu (New Zealand); 1996 | Flashover at substation due to water (from clean-up operations) settling on ash-covered insulators. |
| Copahue (Argentina); 2000 | Heavy ashfall cut off power for several hours and eruption-related damage also cut off the power supply. |