The three different types of Surge Protection

There are three types of SPD required for home & business surge protection. Think of them as bands of protection. Type-1 guards against extremely large mains power surges of 40,000 amps+ and is installed on the external mains service panel where the street power is connected to the home. The Type-2 SPDs help catch the 20% of power surge that leaks past the Type-1 layer, typically rated at 200 amps+ and is installed on each distribution and branch sub-panel e.g. garage sub-panel breaker box. Type-3 is the last layer of defense and is installed at “point of use” power outlets and coaxial, ethernet, HDMI connection points e.g. household appliances, home office, entertainment systems, gaming rigs and network devices. It is important to note that you need to protect, not only against power surges through the homes mains power circuits, but also against electrostatic discharge (ESD) which radiates throughout the house.

The three types of surge protection


Type-1 Main Service Panel and External Power Connections

The first level of SPD is installed on all the external main service panel, sub-panels, and connections outside the house, including air conditioning compressor units, pool pumps etc. These guard against the big surges of 40,000 Amps+ before they even get into the house. A licensed electrician is required to do this work and you should also get them to test and make sure the house ground wiring and prongs are installed correctly. Make sure the devices you use have thermal fuses and have lights or alarms that notify you that you have been hit. Note that these devices typically stop 80% of the surge in nanoseconds meaning 20% will still leak into your house and should be caught by the next level of type-2 SPDs installed at all the internal distribution and branch sub-panels.

Type- 2 Internal Distribution and Branch Sub-Panels

This second level of surge protection is installed at each sub-panel branch from the main service panel (usually in the garage distribution breaker box). This will also require a licensed electrician. Type-2 SPDs are more sensitive than type-1, typically rated at 1000+ amps. This will stop most of the surge, and trip in a nanosecond. Even so, 10% of the remaining surge will still leak through to the point of use, and this is where the next level of type-3 specialized trip plugs, power strips and UPS (uninterruptible power supply) devices come in as the last line of defense.

Type-3 The last line of defense for appliances and devices

Type-3 SPD devices are installed at “point of use” and protect against any surge that leaks past the type-2 SPD, or any electro-static discharge (ESD) or electrical fast transient bursts (EFT/B). Any wire containing copper can be a conduit and should be considered, such as: Power Outlets, Coaxial/Ethernet CAT/HDMI cables, Speaker and LED wiring. Type-3 SDPs should be placed as close to the protected device as possible and be properly grounded using a short AWG 12/14 ground wire. There are many different types of type-3 SPD using trip mechanisms, gas discharge tubes, Varistors etc. they should be able to handle the maximum surges possible for the type of connection. Type-3 SDPs are typically used to protect appliances, office equipment, entertainment centers, security systems and networks.

Power outlets

Power outlets vary depending on the amp and voltage requirements. For example the following table lists the typical breaker sizes used in the USA.




3/5-ton HVAC, Car charger






Clothes dryer, Water heater



Refrigerator, Freezer, Dishwasher, Washing Machine, Pool pump



General household devices



60/50/30-amp power connections are usually protected by type-2 SPDs. General 20-amp appliances use a specialized trip type plug, and the rest of the 15-amp household devices use power strip or single plug SPDs. It is extremely important to use the correctly rated SPD.

Coaxial, Ethernet, HDMI, Speaker, LED cables

Damaging power surges can easily fry the sensitive electronics and circuitry in devices connected by coaxial RG6, Ethernet RJ45, HDMI, Speaker and LED cables. These surges can emanate from electrostatic discharges (ESD) or by connected devices hit directly by a power surge. Each of these cable and wire types has a specialized SPD. These are described in more detail in the following sections. Use only grounded SPDs, its worth the extra work.

Additional information:

Download our free Surge Protection PDF. 

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