This depends on the lifespan of the key components of the LED street lights, which include the pole, the light, the controller, the driver, and so on. The LED light has a very long service life, and the good ones can last for 10 years. Stainless steel and solid poles can resist the harsh weather and work for over 10 years. The lifespan of the controller can be 5-8 years, and that of the driver can be 3-5 years. So you will need to replace different components at different times.
The street lamps connect to the power grid, and then the transformer and distribution box change it into suitable one. Through the urban power grid: