Choosing a Surge Protector

Choosing a Surge Protector

Choosing a Surge Protector

Surge protector or TVSS (Transient voltage surge suppressor) is the equipment designed to protect your electrical equipments (loads) and AC electrical circuits from power surge or voltage spike. Surge protector diverts the excess voltage and current into grounding wire.

Your electrical equipments can be exposed to damaging surges from AC power line and telephone or signal lines. Surge protector helps to protect equipments from lightning surges, switching surges and voltage spikes. Many factors influence the selection of the right surge protector as follows:

Surge protector location

ANSI/IEEE C62.41-1991 standards provide the location categories for the correct selection of surge protector. It defines three categories of surge level, based on strategic location within a facilities wiring network, where power problem may be encountered.

Category A

  • �Outlet and long branch circuit panels
  • �All outlets at more than 10 metres (30 feets) from category B location.
  •  All outlets at more than 20 metres (60 feets) from category C location.

    Category B

  • ��Feeders and short branch circuits.
  • ��Distribution panel devices.
  • ��Bus and feeder industrial plants.
  • � Heavy appliance outlets with �short� connections to service entrance.
  • � Lighting systems in large building.


  • Category C
  • �Outside and service entrance.
  •  Service drop from pole to building
  •  Run between meter and panel.
  • �Overhead line to detached building
  • �Underground line to well pump.
  • �Exposed or critically important sites.


  • These three categories; A, B and C, determine that what level of surge protection each location need as shown in the figure below.


    Clamping voltage

    Clamping voltage is the voltage at which a surge begins to work by conducting electricity to the ground line. A lower clamping voltage indicates better protection, but a shorter life expectancy. Clamping voltage is also often called �Let-through voltage�, but the two are not actually the same thing. The let-through voltage is the voltage that is allowed to pass on to your equipments by the surge protector.

    Energy absorption/dissipation (Joule rating)

    Joule rating indicates the amount of energy that surge protector can absorb without failure. A higher joule rating indicates the better protection because surge protector will divert more energy elsewhere and absorb less energy resulting in a lower voltage spike.

    Response time

    This rating indicates how fast a surge protector can react. The longer response time tells you that the connected equipments will be exposed to surge for a greater amount of time. Choose a surge protector that responds in nanosecond.

    Indicator lights

    Surge protector with indicator lights let you know the surge protector is functioning properly whether or not.

    Surge protector connectivity

    Choosing a surge protector depends on what sort of equipment you are connecting to power supply. Some surge protectors can protect your equipments from surge damage on wall outlets connection and from telephone or signal lines connection, too. Some surge protectors can protect only surge damage on signal lines connection.


    • Surge protection on all electrical wires: Make sure that surge protection is on all electrical wires. Surge protector should indicate protection for Line to Neutral (L-N), Line to Ground (L-G) and Neutral to Ground (N-G)
    • Telephone line protection: Look for a surge protector with telephone jack for protecting telephone, computer, fax and modem from power surge on telephone lines.�
    • Coaxial line protection: Look for a surge protector with coaxial jack for protecting TV or VCR from power surge on coaxial lines.


    Proper grounding imperative

    Without proper grounding, surge protector�s ability to protect against power surge will be diminished.

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