Experts recommend the Series Mode type for modern computing systems, or any sensitive electronic system that may be interconnected with other electronic systems. A heavy duty surge reactor acts to deflect surges rather than diverting surges where they can do further harm.

The following list of specifications should be carefully examined and compared:

  1. Let-through voltage at maximum rated surge (not simply clamping level, which is the onset of clamping) using standard test pulses. (Let-through voltage is the amount of the surge voltage that is let-through to your protected equipment and should be as low as possible. 180 volts is the theoretical lower limit for 120 volt power lines).
  2. Service life for various surge levels (including maximum rated surge). A service life of 200 minimum worst-case surges is recommended for a five year life in high exposure locations.
  3. Filter response. (i.e. greater than 30 dB at 100 kHz.) The important frequency range for surges is 5 kHz to 500 kHz. Greater than 20 dB at 100 kHz is desirable.
  4. Safety Ground Wire contamination should be avoided if equipment is to be interconnected. Suppressors that claim “all three modes of protection” divert surges to the Safety Ground Wire and should not be used with interconnected equipment.
  5. Self-test or failure indication (not “protection working” indicators which are often little more than power applied indicators).