What factors contribute to the diversity of electrical voltage standards across different countries, and what are the primary voltage categories used worldwide?

The variation in national voltage standards stems primarily from historical technological competition and colonial influence. During electricity's early development, Thomas Edison advocated for 110V DC systems, while Nikola Tesla promoted 240V AC—with AC eventually proving superior for long-distance transmission. The United States retained Edison's lower voltage foundation, evolving into modern 110V AC networks, while European nations adopted Tesla's higher-voltage approach. Colonial-era standardization further entrenched regional differences as imperial powers imposed their electrical systems on territories.   Globally, electrical systems are predominantly categorized into two voltage types: residential/single-phase (designed for household appliances) and three-phase (utilized for power transmission and industrial machinery). Three-phase systems operate at higher voltages to efficiently deliver power over long distances and drive large equipment, while single-phase configurations prioritize safety for domestic use through lower voltage levels. Current national standards remain influenced by these historical technological pathways and colonial legacy, resulting in the diverse voltage specifications observed worldwide.