Important Information About UL You Need to Know

 MCG Surge Protection, along with other manufacturers of SPD equipment, have long complied with UL standards in oder to be able to carry the UL mark - a universally recognized symbol of safety to industry, users, specifiers, and the insurance companies that underwrite the protected equipment and facilities.

In 2006, a new standard was released titled UL Standard for Safety for Surge Protective Devices, UL1449 Third Edition, dated September 29, 2006. As a result, manufacturers were required to retest products to ensure that they comply with the new standard by 9/29/2009. The new standard adds:

  1. Consolidates transient voltage surge suppressors and surge arrestors into a single category: surge protective devices (SPD)
  2. Classifies transient voltage surge suppressors (TVSS) and sure arrestors into four categories - Type 1, 2, 3 and 4.
  3. Changes the UL rating from SVR (Suppressed Voltage Rating) to VPR (Voltage Protection Rating) which is performed at a higher surge current level of 3kA, as opposed to 500A for the SVR. As a result of this, VPR data are usually higher than the older SVR due to the higher amplitude surge current used to establish the VPR.
  4. Adds the Nominal Discharge Current (In) test sequence which subjects the SPD to a sequence of surges at a current level chosen by the manufacturer. This is analogous to an "accelerated life test" which compares protector performance before the test sequence and after the test sequence to ensure that the protection circuits are still functioning within specification
  5. Requires new markings on the protector such as:
  • SPD type (Type 1, 2, 3 or 4)
  • Nominal Discharge Current (In) rating i.e. In=5kA
  • Maximum Continuous Operating Voltage (MCOV)
  • Date of Period of Manufacture
  • SCCR (Short Circuit Current Rating)
  • VPR (Voltage Protection Rating)

Also, a new gold UL holographic label with the term "SPD" on it is used to differentiate the new UL1449 3rd Edition Listed products from the previous UL1449 2nd Edition products.

Other companies elected to bypass UL altogether and test to the new requirements using and independent, non-UL lab. In this case, it is the lab's interpretation of the UL standard that is in question, as the products may not be tested in the same manner that UL tests them. Cost savings are substantial and turnaround is significantly faster. Problem - testing to the standard and being compliant to the standard does not confer a UL listing. If there is no UL listing, there's no UL mark. It cannot be displayed on any units tested outside of UL.

Manufacturers who used other labs are taking great care to make it look like their products are UL listed, or in the even a potential customer reads the fine print, to assure that UL compliant is the same as UL Listed. They use the words, "Products Listed or Compliant to new UL Requirements", and even wrap them in gold starbursts for authenticity.

Big Question: If TVSS (or any other electrical equipment) is not UL-Listed, will your insurance company pay on claim should a calamity, such as a fire or an explosion, occur?

Conclusion: Read the specs and visit the UL website - UL Listed means a unit may bear the UL mark. UL compliant units tested outside of UL will bear the mark of the independent testing lab, not the UL label.

MCG has invested the time and money in the UL Listing. We meet the specs and can legitimately display the UL mark on our products. Click here to see our listing: 


Go to "Begin a Basic Search" and type: "MCG Electronics" into the company field and click on the "Search" or press "Enter" on your keyboard.


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Christine Jelley


MCG Surge Protection