House Current PowerEdit
From a house gets some of the 240VAC for HVAC (Heating Ventalation and Air Conditioning) only for the condenser units for cooling, and also 120VAC goes to the rest of the house, powering a TV, an Oven, a Microwave oven, etc.
Commercial and Industreal PowerEdit
These ones are using 277/480VAC power, by a Three Phase Transformer, on a pad mount or pole mounted. Inside of the electical room, there is a small transformer which converts it to 240/120VAC.
A substation is a power source for step down power for Distrubution Lines, from the Transmission lines.
Transmission Lines start at Power Plants, then go to Substations to distribute power though lower voltage lines. In most cases to a lower Transmission Voltages or Sub-Transmission Voltages. And sometimes straight to Distribution Voltages. Transmission Line Voltages veries to how long of a distance the line is going for or how much energy is gong to used thought the line. Transmission Voltages most commonly used are 110kv, 115kv, 138kv, 220kv, 230kv, 345kv, 380kv, 400kv, 500kv, 765kv, and 1000kv. More rare of Transmission Voltage would be 161kv used by very little power companies.
Sub-Transmission Lines are between Transmission and Distrubution.
Distribution lines are wooden or iron poles that have insulators, and components like for example: Transformer, or a Capacitor Bank.