Summary & Conclusion:

Outdoor luminaires are susceptible to transient spikes caused by power system switching, direct lightning strikes, and indirect lightning strikes. The older methods of lighting, such as mercury vapor, metal halide or sodium vapor lights, relied upon their robust construction to suppress any transient voltage spikes. LED lighting isn’t afforded that luxury and voltage transients can destroy drivers and the LEDs themselves. Due to the sensitive nature of LED lights, numerous studies have been conducted and resulted in the creation of IEEE C62.41.2-2002 with suggested surge levels. In addition, UL released UL 1449 in 2007which has become the primary safety standard for surge protective devices (SPDs). The LED driver without external surge protective device is designed to handle surges in the 2-3 kV range. To achieve a system IEEE protection level of 20 kV/10 kA, the external SPD is required. It is recommended that 3 levels of SPD protection be offered, see Table 3 for details:

  1. 1. Standard Protection: Standard in all fixtures regardless of geographical location or Modified Warranty: If fixtures are sold without at least the standard protection for lightning prone areas as shown in Table 1, the warranty is reduced to 1 year
  2. 2. Protection Upgrade 1: Upgrade option that would offer IP66 and thermal cutoff that would meet UL 1449 requirements for SPDs
  3. 3. Protection Upgrade 2: Upgrade option that would offer IP66, meet UL 1449, thermal fail-safe, disconnect luminaire from circuit to prevent damage during next transient event, failed SPD indicator, and ability to mount the SPD in steel poles


  • • Parallel SPDs do not protect the fixture from subsequent lightning strikes after it has been subjected to a transient surge
  • • Series SPDs will protect the fixture from subsequent lightning strikes after it has been subjected to a transient surge
  • • Series SPDs can be pole mounted if pole is steel
  • • Indirect lightning strikes several miles away can still create a damaging transient surge
  • • Power system switching can cause a damaging transient surge
  • • Top 10 states for lightning strikes: Texas, Florida, Oklahoma, Missouri, Kansas, Arkansas, Louisiana, New Mexico, Illinois, Mississippi
  • • Most prevalent months for lightning strikes: May, June, July, August
  • • SPDs need to be disconnected during HiPot testing; this test may damage the SPD and reduce its life and effectiveness
  • • NLS Non-conforming data for Q1 & Q2 2018 indicate a correlation between increased driver failures and lightning season. Further data analysis should be performed to determine a causal effect