A revision of UL 1449 went into effect on February 9, 2007. This revision adds intermediate fault current tests for SPDs (surge protection device). Before the February 9 revision, only high current fault current testing was specified by UL 1449. 


When UL tests a SPD, they apply a fault current of 100A, 500A and 1 kA for permanently connected SPDs and 50 A and 150 A for plug-in and cord connected SPDs. These currents are applied using line to line voltage in the line to neutral mode. During this testing, the SPD must fail in a safe manner to be UL 1449 listed. In the event that the SPD does not conduct the defined current, UL can increase the voltage or request a sample with a lower voltage rating.

Product Labeling

As of February 9, 2007, any SPD manufactured must have passed all of the abnormal power tests to be labeled with the UL logo. 

UL 1449 3rd Edition

A new revision of UL 1449 required compliance by 2009. The 3rd Edition increased amperage six times from the 2nd Edition to 3 kA at 6 kV. 

The kA rating, up to 20 kA, will be identified by the SPD manufacturer and tested by UL. UL will subject the SPD to 15 surges at the manufacture’s defined In, level, minimum of 6 kV. The VPR is tested again after the SPD successfully passes the 15 surge In test. If the associated VPR is consistent with the SPDs original test, the rating can be applied to the SPD label. 

Newsletter Signup