If you are specifying surge protection for a modern electrical installation, one of the most important decisions is whether to use a Type 2 SPD or a Type 1+2 SPD.
Both are designed to protect equipment from transient overvoltages, but they are used in different scenarios depending on the installation type, exposure risk and incoming supply conditions.
Choosing the wrong type can leave parts of the system unprotected - or lead to unnecessary overspecification.
Browse our full range of Surge Protection Devices, including Type 2 and combined Type 1+2 units.
Quick Answer: Use a Type 2 SPD for most domestic and standard commercial installations. Use a Type 1+2 SPD where there is a higher risk of direct lightning currents entering the system - such as buildings with lightning protection systems (LPS) or overhead supply lines.
| SPD Type | Used For | Typical Install |
|---|---|---|
| Type 2 SPD | Switching surges and indirect lightning | Most homes and standard commercial installs |
| Type 1+2 SPD | Direct + indirect lightning currents | Buildings with LPS or high exposure risk |
🧭 Jump to:
What Is a Type 2 SPD?
A Type 2 SPD is designed to protect against transient overvoltages caused by switching events and indirect lightning strikes.
This is the most commonly used SPD in modern installations and is typically installed:
- In the main consumer unit
- In sub boards feeding sensitive equipment
- In EV, solar and heat pump boards
For most domestic and light commercial installs, a Type 2 SPD provides the required level of protection.
What Is a Type 1+2 SPD?
A Type 1+2 SPD combines the functions of both Type 1 and Type 2 protection.
It is designed to handle:
- Direct lightning currents entering the building
- Secondary transient overvoltages
These are typically installed where:
- The building has a lightning protection system (LPS)
- The supply is overhead and exposed
- The installation is at higher risk of direct lightning influence
Key Differences Between Type 2 and Type 1+2 SPDs
| Feature | Type 2 SPD | Type 1+2 SPD |
|---|---|---|
| Protection Level | Indirect surges | Direct + indirect surges |
| Typical Use | Domestic installs | High-risk or LPS installs |
| Cost | Lower | Higher |
Which SPD Should You Use?
For most installs, the decision is straightforward:
- Standard domestic property → Type 2 SPD
- EV charger, heat pump, solar PV → Type 2 SPD (often built into the board)
- Building with lightning protection system → Type 1+2 SPD
- Overhead supply / exposed site → Consider Type 1+2 SPD
Many modern boards already include Type 2 SPD as standard, especially in EV and renewable-ready consumer units.
Installer’s Tip: For most EV and domestic installs, a consumer unit with built-in Type 2 SPD is the simplest and most reliable option.
Common Mistakes to Avoid
- Using Type 2 where Type 1+2 is required in LPS installations
- Over-specifying Type 1+2 when Type 2 is sufficient
- Assuming all SPDs are the same - they are not interchangeable
- Ignoring supply type and exposure risk
Regulation Reminder: BS 7671 requires consideration of surge protection based on risk assessment, installation type and consequences of overvoltage. The correct SPD type must match the level of risk present.
Final Word
The difference between Type 2 and Type 1+2 SPDs comes down to the level of protection required.
For most installs, a Type 2 SPD is the correct and cost-effective choice. But where lightning risk is higher, stepping up to a Type 1+2 device ensures full protection.
👉 Compare options in our surge protection range or explore SPD-ready consumer units for fast installs.