What should I do if the cost of connecting three-phase electricity to the property is unreasonable?

You can negotiate with the property, or you can find another electrician to answer it yourself.

Additional power connection needs the following expenses: interface fee of power distribution room, wire fee, meter box and accessories fee, labor fee, etc.

China's property fee collection standards are divided into first-class property fee standards, second-class property fee standards, third-class property fee standards and fourth-class property fee standards. The collection standard of property fees varies from place to place. The specific collection standard of property fees is announced by the local price bureau, and property management fees include many aspects.