In this thesis, the development of electrical porcelain insulators based on local clays has been investigated. The test samples were made by varying the quantities of silica and feldspar required to form a mouldable plastic body with each clay sample. The clay samples were bisque fired to 900°C and glazed before it was fired to 1250°C after air-drying. Electrical properties such as dielectric strength (breakdown voltage) were determined for each test sample that survived the high temperature. The composition for optimum properties from Ekwulobia and Iva Valley clays each is at composition 3 of 60% clay, 25% feldspar and 15% silica; while for Nawfija clay, the composition for optimum properties was 50% clay, 30% feldspar and 20% silica. Then, the snail shell was grinded into a powdered form to be used as an additive. The snail shell additive was added to the sample composition 3 (clay 60%, feldspar 25% and silica 15%) from each location in five compositions as stated in table 3. Porcelain insulators containing 50-70% clay, 20-30% feldspar and 10-20% silica were found to possess requisite properties that make them suitable for domestic production of porcelains insulators from the clays studied.
