Advantages of single phase and three phase system

• A three-phase service requires three high-voltage transmission lines and three transformers , while a single phase service requires only two high-voltage lines and only one transformer .  
• Three phase motors draw less current than single-phase motors of equal capacity , although the power required is generally about the same . 
• A three-phase motor with the same power capacity draws less current per wire , and therefore can use a less expensive , lighter-gauge wire . 
• Three-phase motors are simpler , lower in cost , more trouble -free , and more efficient over a wide range of loadings thant heir single-phase counterparts .