UL 1449: Transient Voltage Surge Suppressors

Addressing product safety.

UL’s safety and performance standard for Transient Voltage Surge Suppressors (TVSS) is UL 1449. This standard applies to end-users, manufacturers, and specifiers. A major revision, also known as UL 1449 Second Edition, became effective in 1998.

End-of-life characteristics are particularly important because TVSS are placed in harm’s way and can affect the rest of the electrical distribution system. Areas of interest include fault current testing, thermal issues, touch-safety, etc. 

Nationally Recognized Testing Laboratories (NRTLs - such as UL, CSA, Intertek, MET Labs, etc.) provide a valuable service to specifiers and end-users by testing the performance of all TVSS/SPDs the same way. This is the only ‘common’ testing format in the industry, making it an important barometer of performance. 

NRTLs assign Suppressed Voltage Ratings (SVRs), applied on the testing lab's approved label. These ratings indicate the clamping, or let-through, voltage based on NRTL testing. Lower numbers typically demonstrate better performance. UL 1449 specifies an SVR based on clamping between specific voltages.  For example, clamping between 331 and 399 would yield a 400v SVR rating. 

An end-user or specifier can compare the performance of different products simply by comparing Suppressed Voltage Ratings listed on the device’s approved NRTL label. Hardwired products also include Short Circuit Current Ratings (SCCRs) for fault current coordination purposes.

How to Buy UL 1449:

UL Standards can be obtained from comm-2000 and additional information at UL's website.

The document is approximately 160 pages and the price ranges between $226 and $519, depending on the type of publication and subscription service the customer selects. See comm-2000 for options.

The next revision is scheduled for June 2004.

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