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What is the UL Listing and Why You May Want it

When choosing an American Rotary phase converter you may see on the website or get asked about the option for the UL listing. For those of you not working in the electrical industry day-to-day, it may spark some curiosity. American Rotary is a UL approved Company that utilizes all UL approved components as part of the assembly of the phase converter. Understanding what UL means will help determine if having a UL certified phase converter is necessary for your installation.

UL stands for Underwriters Laboratories which is an independent safety science company that tests and certifies products with respect to their safety. If the relevant sample passes the test in any given case, it merits a “listing” which can be seen online at Once a unit has been UL listed it means a representative of UL has tested a sample of the product and determined that it meets UL’s requirements. They base these requirements on UL’s published and nationally recognized Standards for Safety.

Having a UL listed certified unit is not legally required. It is, however, a common practice because many large companies will only buy equipment that has passed the UL safety tests. It is also common business practice in the United States to only sell products that have a NRTL (Nationally Recognized Testing Laboratories) label. It doesn’t have to be UL per se, but a recognized marking is advisable. If a unit has a cULus Listing on it, that means that UL has tested the unit meeting Canadian and US standards. Having a tested product shows that the equipment meets a nationally recognized safety standard.

At American Rotary, we use all UL approved components in the assembly of our phase converters. American Rotary Phase Converters have been tested and approved by UL to meet their safety requirements. This means when using an American Rotary phase converter you will meet any additional safety requirements that your inspector may require. If you are having your installation inspected by your local inspector, it’s important to check with them prior to ordering your phase converter to see what is required to pass inspection. Some cities require the phase converters to include the UL documents in addition to being UL approved.

When the UL documents are required, this gets you all the information that some inspectors will require. This includes but is not limited to the UL licensing numbers, UL forms showing the phase converter does meet UL safety requirements, and other additional documentation on the phase converter. To prevent downtime, it is better to know what is all required upfront prior to any installations.

If you have any questions you can always call American Rotary. We are always willing to help our customers make the American Dream their reality.

4 thoughts on “What is the UL Listing and Why You May Want it

  • Joe Rose

    April 23, 2017 at 10:12 pm

    I have been looking for years for a solution to an issue. I have 3 phase 208 power in my shop and have been using it to run several applications that really need 240 single phase. Not particularly interested in paying for an additional service drop. Do you make a phase converter from 208/3 to 240/1? I have lost several pieces of valuable equipment over the years by running them underpowered.

    • admin

      April 27, 2017 at 3:22 pm

      Hi Joe, We’d like to learn more about your situation before providing an answer. Please give us a call at 262-402-6400 and we will be glad to help.

  • Rick Cohee

    June 4, 2017 at 11:34 pm

    I purchased an AD-15, 208 – 230V rotary phase convertor from you a couple of years ago. It has worked flawlessly so far. I am considering purchasing another metal lathe which is 6 HP, 2 speed 440V only. I have access to a 440v to 220v, 3 phase 9 KVA step down transformer. I am aware that reverse feeding a transformer causes an initial increase in current draw at power up.
    My actual question is, with this initial increased rush of current draw, will that have unadvisable and/or damaging consequences on the RPC? Do I need to change the caps? What are my options to be able to use this lathe with my present RPC?

    Thank you.

    • admin

      June 20, 2017 at 2:45 pm

      Hi Rick,

      Please give us a call at 262-402-6400 and one of our application engineers will be glad to get you exactly what you need!

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