State laws cover this- look in the Consumer Protection area on your state's site. Federal, too- you should know this.

UL lists products after testing as having passed, they don't approve. If they did, they would be liable in the event that something fails.

There's a lot that we, as integrators who sell products should know, but often don't. I don't know about CA, but in Wisconsin, anything sold off-site (not at the main place of business) has a three day window for returns, so it's not a case of "All Sales Final" when we sell something at their home, business or if we hold a sale in any place other than a fixed location. Since we don't always have a retail location, this means three days, no whining if they don't like it and that means we need to be careful about making sure we communicate well with the buyer.

Another thing we have in our favor, as businesses that sign a dealer agreement, is the statute that prevents manufacturers from pulling a line on a whim, just because they may have a friend who has opened a business and they want to do a favor. It's good for dealers who are doing a good job with the products, but bad for the manufacturer whose dealer may be a complete turd- they can't be cut off, either. However, the manufacturer is free to add a dealer close to the one they want to cut off, but they need to watch out for the territory boundaries, if that applies.