from article: "4. How long does it take to get a UL product certified or listed? Normally around 6 months, counting from the day you have a functional prototype. That said, it can take months (or even years) before you have a prototype that is technically compliant with all applicable UL standards.
Not any product can be submitted, and magically pass all UL testing procedures.
Unless the product is specifically designed according to the technical requirements set out in the applicable UL standard – then the product will not pass compliance testing."
from article: "2. Is UL listing or certification mandatory when importing from Asia? No, compliance with UL standards is not mandatory, in the sense that you are not required by law to follow them. When it comes to importing electronics to the United States, it’s up to the importer to ensure that the product is safe.
One way to achieve that, is by following a certain standard, be it one developed by UL, or another organisation.
That being said, UL is the ‘de facto’ set of mandatory electronics safety standards, in the United States."