We are looking into providing a new model of our product.  Currently our product uses NO Electrial/electronic power to operate.  We (at the customer's request) are looking into possibly supplying a listed electrical motor and starting capacitor mounted to a frame along with other mechanical components.  We will supply a cover over this assembly.  Must we get a third party test/review.

It really depends what the product is used for and how it is installed. For example if the product is a component of a final system and the main power input goes to some type of main control panel that will protect your motor than you probably can get away with it. If your product is powered on is own for an intended purpose than you will need to go through an approval process. It is not mandatory but you will have a very hard time getting someone to purchase it without an final system approval. You should refer to the applicable UL standard for the product and make sure you are designing the electrical circuit appropriately. It is necesssary to protect the motor, I recommend you buy a motor that already has thermal protection. This will allow you to go directly to the fused or CB Disconnect device without any other additional protection.

If you have more questions feel free to contact me.

Christopher Caserta
ccaserta@us.tuv.com
Ph:904-225-0360

I agree with Christopher. It is not a requirement but getting someone to buy it will be difficult and may need to be UL listed or recognized later because of a local inspector. For industrial control panels, I believe you want to look at UL508A and for other components, like Overloads, over-under voltage, it will be under UL508.
I would ask your customer if they require this. They should know. If they don't need it then you don't need it either.