5 Benefits of plastic enclosures in USA, Germany, France, UK, Italy, India when choosing the right material for your enclosures.
Intrinsic Insulator
The main difference between the plastic and metals used to create electrical enclosures is that it doesn’t conduct electricity. This feature is especially important if there are concerns about electrical shortage or the equipment will be used near water.

Another great point about plastic enclosures/junction boxes that they don't need to be grounded. That is, they don't need a ground connection to the enclosure box itself. By contrast, metal boxes, which are conductive, must be grounded to the circuit grounding system, normally with a short wire called a pigtail that connects the box to the circuit's ground wire(s).