The use of plastic electrical boxes for hanging ceiling fans is generally not recommended. Ceiling fans are heavy and can put a significant amount of stress on the electrical box and the mounting system. Plastic boxes may not be designed or rated to support the weight and movement of a ceiling fan, which could lead to safety issues over time.
For ceiling fan installations, it is essential to use electrical boxes specifically designed and rated for ceiling fan support. These boxes are typically made of metal and have stronger mounting points to handle the weight and movement of the fan without compromising safety.
If you want to install a ceiling fan in your new construction home, you should replace the existing plastic electrical boxes with proper metal-rated ceiling fan boxes. This will ensure a secure and safe installation. If you are not familiar with electrical work, it's best to hire a licensed electrician to perform the installation to ensure everything is done correctly and up to code. Your safety is of utmost importance when dealing with electrical installations, so it's better to be cautious and seek professional help when needed.