TVSS = SPD ~ Surge Protection

As of September 29, 2009, the newest UL 1449 3rd Edition safety standard for Surge Protective Devices (SPDs) is in effect. If you are responsible for protecting critical electrical systems, you need to know about these changes!

At a Glance the changes are:

• Suppressed Voltage Rating vs. Voltage Protection Rating - The SPD’s let-through voltage is now measured as it is subjected to an IEEE defined 6kV/3kA “combination waveform".
• Nominal Discharge Current (I_n) - The SPD’s Nominal Discharge Current capability, up to 20 kA, is now reported with the suppressor’s specifications and on its labeling.
• Suppressor Categories - The new standard categorizes SPDs as one of four designated types based upon whether or not they are a component, and where within an electrical distribution they are to be installed.
• TVSS is now SPD - The term identifying a surge suppressor as Transient Voltage Surge Suppressor (TVSS) was retired and will now be called a Surge Protective Device (SPD).
• Extended Scope - 3rd Edition UL now governs suppression products designed to protect on electrical circuits up to 1000 V.

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