Surge protectors, or SPDs, are the first line of defense against power surges.  They protect your expensive electrical equipment and household appliances from everyday spikes and surges and larger ones due to lightning strikes or other power anomalies.

Surge protectors are designed to divert the excess voltage to ground, protecting the electrical system and equipment from damage. Surge protectors come in various forms, including point-of-use power strips with built-in surge protection and whole home surge protectors, which are intended to protect appliances that are permanently wired in and can’t otherwise be protected—like your AC, furnace, stove, thermostat, etc.

There are 3 types of Surge Protectors (SPDs):

  • Type 1:

    Designed to be permanently linked and installed between the secondary of the service transformer and the line side of the service disconnect overcurrent device (service equipment). They primarily serve to safeguard electrical system insulation levels from external surges brought on by lightning or utility capacitor.

  • Type 2:

    Designed to be permanently attached and installed on the load side of the service disconnect overcurrent device (service equipment), including brand panel locations. Their major function is to shield the delicate electronics and microprocessor-based loads from surges caused by motors, leftover lightning energy, and other internally induced surge events.

  • Type 3:

    Point-of-utilization, a minimum of 10 meters (30 feet) of conductor must separate the electrical service panel from the place of use before installing SPDs. Examples include direct plug-in, cable connection, and receptacle type SPD.

Whole Home Surge Protectors

Power surges aren’t so much an “if” as a “when.”  Power spikes are a common occurrence wherever you live. Repeated low-level surges from a faulty transformer or a brownout can be the most damaging over time—shortening the lifespan of pricey appliances and electronics.

Around 80% of power surges happen within the home and not from an outside source. Some only last a fraction of a second as appliances power up or down. Still a jolt of excess electricity can damage everything from your computer and TV to your refrigerator and HVAC compressor.

Fortunately, SPDs prevent this type of damage and are surprisingly affordable—particularly when compared to the cost of the appliances and electronics needing replacing. What type do you need for your home?  Read on.

Type 1 or Type 2?


Type 1 surge protectors are line-side devices installed between your home’s utility cable and the main breaker panel. They provide the highest level of protection from external and internal surges. Type 2 surge protectors are installed after the main breaker panel or in a sub panel, protecting one or several circuits from internal surges. Some SPDs are both Type 1 and Type 2 and can be installed in either location.

Type 1 protectors must be installed by a certified electrician. Not using a professional to install it will likely invalidate any home insurance should a fire or fault occur.

Anyone with decent knowledge of the main breaker panel can install type 2 devices. However, hiring a professional electrician is not a bad idea since you are dealing with high voltages.

Many homeowners elect to install several SPDs for layered protection, particularly if there’s a significant distance between the SPD and the protected equipment.  If you’ve invested in expensive equipment, such as a home theater, HVAC, or pool/spa equipment, it makes sense to double up on protection and install a Type 1 or Type 2 whole-house surge protector and add on a Type 3 for sensitive electronic equipment.

The right SPD for you will depend on your home’s setup, the types of electronics and appliances you need to protect, and how often you experience high-risk events like lightning storms and power surges.

Before purchasing, you’ll want to determine where your SPD will be installed so you buy a model with the appropriate enclosure and dimensions that will fit your location – inside or outside the breaker box? Indoors or outdoors?

Features to Look for When Buying SPDs

Depending on your needs and budget, there are different types of surge protectors for residential use. There are several things to look for.

1. UL-Listed or ETL Certified

Underwriters Laboratories and the Electromagnetic Test Labs are the two major testing companies that test surge protectors. Any SPD you purchase should be UL or ETL certified.  When shopping for a surge protector, you will see both UL and ETL labels. Surge protectors are only required to have one of these labels.

2. NEMA Rating

National Electrical Manufacturer Association (NEMA) uses a standard rating system that defines the types of environments in which an electrical enclosure can be used. These ratings are crucial to knowing where a device can be installed.  A rating of NEMA 1 indicates indoor use only, while a rating of NEMA 4X indicates a waterproof enclosure that can be used indoors or out and offers protection from the elements.

3. Surge Protection Rating

The amount of electrical current an SPD can absorb is measured in kiloAmps (kA). Generally speaking, higher numbers mean more protection. The best whole-house surge protectors are 30 kA or higher to ensure all your appliances are protected. If you live in a high lightning zone, at least 40 kA is a better choice.

4. Compatibility

The SPD you select must be compatible with your breaker box’s manufacturer and your electrical system’s current. Double-check that this is the case before purchasing. Also, if you’re installing a whole-house SPD inside your electrical panel, make sure there’s enough room inside to accommodate the dimensions of the SPD you’ve selected.

5. Warranty

Check the length of the SPDs warranty to see the duration of coverage and what dollar value it covers.  Most whole-house SPDs come with a limited 10-year or lifetime warranty, plus residential damage coverage up to a specific dollar amount if the device fails.  If you have expensive or irreplaceable gear, it may be worth the extra cost for a surge protector offering more generous warranty coverage.

Note that cheaper SPDs may need to be replaced more frequently, some after just one significant event, like a lightning storm. While SPDs experience different lifespans based on component wear and the frequency and severity of power surges, most manufacturers claim a life expectancy of around five years. SPDs generally have an LED indicator that will show if the unit is operational or needs to be replaced.

The ICM518 is a UL Listed Whole-Home Surge Protective Device that can be installed as a Type 1 or Type 2 with a maximum surge current of 100 kA. It includes a NEMA 4X watertight enclosure. It has a limited lifetime warranty and up to a 3-year $10,000 connected equipment coverage.  It offers affordable, high-performance protection.