The effects of moisture content and spherical shaped silica filler concentration on the resultant tree growth characteristics are explored using Euclidean and fractal geometries. A nano-composite material of MgO added LDPE was subjected to electrical treeing breakdown investigation, as well. As results, the filler particle would create such an obstruction to the tree propagation even if the specimens were moisturized. Moisture would weaken the dielectric strength of resin and the interface. From fractal dimension analysis, it is shown that the complexity of composite structure is followed by...