Investigating the electrical conductivity of volcanic ash and its effect on HV power systems

► Dry volcanic ash is non-conducting. ► ρ of volcanic ash decreases with increasing moisture, soluble salts and compaction. ► All grain sizes can exhibit low ρ levels and have similar potential to cause flashover. ► Coarse-grained ash may be the most conductive due to increased permeability. ► Our ρ method is suitable for small volume, in-field analysis of fresh volcanic ash.