UL Listing Number

Contact any of the dozens or hundreds of registered testing labs that do UL testing.

Google UL testing.

Prepare to break out your checkbook.

You pretty much find out what kind of testing the UL lab is going to do and you do those test yourself to make sure it passes their test. Then you submit a package deal consisting of how ever many parts they require for testing a print of the item and a list of parts that are going to go in it. Then you hope and pray it passes and start writing a check or getting a loan because they are very expensive. We have had items here cost as much as $22,000.00. As far as I know this is how it's done here.

We applied for UL listing on a modern closed-loop electronic LPG fuel metering & control system used on a new forklift engine (used inside buildings - hence needing UL listing). Not being experts, we ran into multiple issues with test procedures that were never known at the beginning of the process. The whole thing took over 18 months and a wad of cash. We even had to justify why certain automotive components already in production (for 5 years) should be allowed to pass with waivers. Some of their test procedures are somewhat archaic and not observed by any other bodies. (i.e. flame tests on plastic parts... doom you to failure.)

The lesson learned was to engage an expert or dedicate the large part of an employee's time for the next few months to the task. I doubt you will see any progress in less than 6 months unless you have been through this before - expect the unexpected.

As stated in previous responses, it can get hairy, it really depends on the product. That being said:

1. Contact UL, the person that answers the phone will make an attempt at your category and send you to a project engineer.

2. Schedule a meeting where you present your products technical features with a focus on shock and fire hazard.

3. The UL engineer will open a project and will start the writing of your file. Your file describes your product in detail and will be used by the UL follow up auditor, who will visit your plant every quarter and do a random audit to make sure you havent switched connectors or something. Note: when writing your file, its a good idea to write it as open as you can get away with. Something like, "control power wire electrically connected to main PWB using recognized connector 123xyz, or suitable recognized equivalent." That way, if you change the connector, you dont have to open a project to modifiy your file, which is currently $1500 I think.

4. Working with UL, you will need to acquire and read the appropriate standards in your category (which UL will tell you). UL will work with you to develop a list of tests which you can run at UL, or you can do at a Lab that is a UL Data Acceptance Program participant. (ETL is one aka Intertek, but there are a ton of others and they are faster and cheaper than UL more often than not.)

5. Once you are done with that process, UL will send you an early authorization letter which will permit you to put the UL mark on your product. Note: the label that has the UL mark has very rigid artwork requirements, and the label must also be a UL approved material. Easiest thing to do is to find a printer that does this work, and can do all the heavy lifting. They already do this stuff for someone else, and they will know more about it than you will ever need or want to know. Let them do it, its worth it.

6. Eventually, UL will send you a hard copy of your file, howver you can see it online as soon as it is complete. Again, a field service auditor will visit your plant every quarter and do an audit of the production floor and verify you are doing it exactly the way your file says you are. If you change something and they catch it, they can stop you from applying the UL mark until you fix it. This will arrive in the form of a "variation notice", and you have a limited time to fix it.

As the others stated, the cost of entry is significant. And keeping it going isnt cheap either. The CE mark is similar except you keep the file yourself (techincal file) and its self certifying, so its up to you to be honest and to make sure all of the required testing is carried out. Are you familiar with the term fractal pattern? When reading the standards, this pattern may occur to you. One standard sends you to another, and that to another, sometimes they loop back, and sometimes they dont; to do it right, you may have to buy 20-30 standards.

Another tip; if your product is complicated and you have several models, make a base file that has most of the details in it, and the differences between the models described in their own file. So then in the specifc model file you can say, "glingrod mechanism described in file E12345 vol 1 sec 1". So that way, all of your models that use a same part can be changed by modifying the base file instead of each and every file that describes the using of that part. Additionally, if you can use UL listed or recognized parts, it can make the process go much faster, cheaper, and easier.

Its not easy.

Nice Info