Where is residential power voltage reduced to home level from the street line level?
The power delivery utility company distributes the AC power to locations away from the power generating stations using high voltages. This is done to help minimize the amount of power loss in the distribution wires and cables. The power loss is always related to the amount of current being distributed to the loads. For each doubling of the voltage used in the distribution network the amount of current for the same load is cut in half.
The voltage levels used will depend in part upon the type, location and distance that section of the power grid needs to deliver electrical power to the consumer loads. Voltages can be in the 1000s of volts.
When high voltage power distribution reaches a residential neighborhood or a business center transformers are used to step the high voltage down to the voltages used in the homes and businesses. Pictures of some typical power transformers are shown below. Typically these transformers are owned and maintained by the power delivery utility company. When you would need service at a particular current level the power company will deploy the proper transformers and then provide a power line connection from the transformer to the electrical usage meter which would be on or adjacent to the home or business.
Typical Transformers:

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