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Type 1 vs Type 2 vs Type 3 SPD

Type 1 vs Type 2 vs Type 3 SPD Thor

The differences between Type 1, Type 2, and Type 3 SPDs can be distinguished in four aspects, namely installation location, protection objectives, surge protection capabilities, and application scenarios.

Installation location: Type 1 SPD is installed at the power supply entrance of the electrical system, close to the main circuit breaker, to prevent severe external large surges. Type 2 SPD is installed in the distribution board as a second layer of protection for the electrical system, blocking secondary surges generated by Type 1 SPDs that are not completely intercepted, and can also block internal surges. Type 3 SPD is installed near the terminal equipment to provide more detailed low-level surge protection for the equipment that needs to be protected.

Protection Goal: Type 1 SPD protects the entire building’s electrical system from external large surges (lightning strikes). Type 2 SPD is used to block internal surges (operating overvoltage caused by human operations, electrical equipment switches, etc.), while Type 1 SPD does not completely block secondary surges caused by large surges. Type 3 SPD focuses on protecting a single or a small group of end devices.

Surge Protection Capability: Type 1 SPD can withstand very high surge currents and protect equipment from large surges such as lightning strikes. Type 2 SPD is suitable for handling most surges and has wide applicability. Its protection capability is between Type 1 SPD and Type 3 SPD. Type 3 SPD is used to handle low-level surges and provide more detailed protection for end equipment.

Application Scenarios: Type 1 SPD is used in industrial facilities and commercial buildings as well as some large electrical systems to prevent risks caused by large surges such as lightning strikes. Type 2 SPD is widely used and is the most common type of surge protector. Type 3 SPD is used in niche and small situations, focusing on protecting a single or a small group of sensitive and high-value devices.

These three types of SPDs need to be used together in practical applications to provide comprehensive protection for the electrical system through different functions and protection levels.


Type 1 SPD

Type 2 SPD

Type 3 SPD

Where It’s Installed

At the entry point of your home/building’s electricity, like the main entrance

On the electrical panel, like the power distribution center of your home

Right next to or directly plugged into appliances, like beside your TV and computer

Why Use It

Protects your whole house when lightning strikes directly or nearby

Deals with smaller surges that sneak in from outside, protecting home appliances

Blocks the last bit of small surges, protecting close-to-heart electronics

How Big a Surge It Can Handle

Can block super big surges, like a superhero in movies

Medium strength, can block most surges under normal conditions

Specifically for small surges, protecting sensitive electronic devices

Ideal For

Places that might get directly hit by lightning, like skyscrapers or factories

Almost every home, shop, and factory needs one

Protecting pricey electronics like computers and TVs