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What is a surge protector?

What does a surge protector do?


Have you ever experienced a bursting water hose?  If you have, this is a result of rising pressure.  If the pressure is greater than what the hose can handle, but not enough to burst, it will weaken and eventually erupt.

The effect of an electrical surge is very similar, when there is too much electrical pressure, or voltage in a circuit, it will cause failure of the circuit’s components.

A surge protector helps protect against electrical disturbances that can travel through these circuits of the home, potentially damaging home electronics and appliances.

Have a question about surge protection?

Download our surge NEC comparison document

Where do electrical surges come from?

There are several sources of power surges.  They can originate from the electrical utility company during power grid switching, to inside the home when large appliance motors turn on and off.



  • Downed or damaged utility lines
  • Lightning
  • Utility grid transfers
  • Intentional power outages

*Does not protect against direct strikes



  • Refrigerators
  • Dryers
  • Garage door openers
  • AC units – compressors
  • HVAC – fans
  • Shop tools – Air compressors, miter saws etc.

Types of surge protection

The Surge Protective Device type (SPD) refers to the location of where the SPD can be used or installed.


SPDs rated Type 1 and 2 are placed here to suppress a large percentage of the initial event.

  • Type 1- Protection is installed before the service disconnect overcurrent device.  Can be installed in Type 2 applications as well
  • Type 2 – Protection is installed after the service disconnect overcurrent device

SPDs rated Type 2 and 3 are placed here to further reduce the voltage let-through from Stage 1.

  • Type 2 – Protection is installed on distribution panels in large homes or industrial applications
  • Type 3 – Protection will tend to be plug-in surge strips, surge receptacles at the electronic device or appliance

Use these tips when applying surge protection

  • Make sure to take two stage approach to residential surge protection, at the service entrance and at the point-of-use
  • Applying partial protection can lead to inadequate surge protection, leaving electronics susceptible to equipment damage
  • Make sure you are staying up-to-date with latest revisions of the National Electrical Code 

Understand the updated NEC 2020 code requirements for surge protection


Every three years, members of the National Fire Protection Association (NFPA) meet to review, modify and add new National Electrical Code (NEC), or NFPA 70, requirements to enhance electrical safety in the workplace and the home.

The NFPA 70, National Electrical Code, creates the foundation for electrical safety.  The updated 2020 version of this reliable code echoes the evolution of the industry, resulting in several updates and four new articles related to the pressing issues of emergency disconnects, ground fault circuit interrupters, surge protection, arc energy reduction and more.