Introduction
In the modern electrical landscape, where infrastructure is increasingly interconnected and sensitive, the Surge Protective Device (SPD) has evolved from a luxury to a non-negotiable necessity.
For industrial facilities, commercial complexes, and critical data centers, the choice between Type 1, Type 2, and Type 3 SPDs can determine whether a system remains resilient or suffers catastrophic failure.
A single lightning strike or severe grid transient can cause millions in equipment damage and operational downtime.
For professional distributors and procurement managers, understanding SPD types is not only about technical compliance but also about risk management and long-term profitability.
At LEEYEE Electrics, we have specialized in low-voltage protection devices since 2009. Operating from our 8,000 m² manufacturing facility with 8 production lines, we supply high-performance SPDs to European, American, and Australian markets.
This whitepaper explains the technical principles, waveform physics, and sourcing considerations for professional buyers.
Part I: The Technical Foundation – Defining SPD Types
Surge Protective Devices are categorized based on their installation location and the type of surge they are designed to handle.
This classification follows international standards:
IEC 61643-11
EN 61643-11
Type 1 SPD: Lightning Arrester (Class I)
Type 1 SPDs are designed to handle direct lightning strike currents.
Location
Installed at the service entrance or main distribution board
Test Waveform
10/350µs impulse current (Iimp)
Function
Diverts massive lightning energy from lightning rods or overhead lines safely to ground.
LEEYEE Advantage
High-capacity Spark Gap or heavy-duty MOV technology
Iimp capability up to 25kA or 50kA per pole
Type 2 SPD: Main Protection (Class II)
Type 2 SPDs protect against indirect lightning strikes and switching transients.
Location
Installed in main distribution boards or sub-distribution boards
Test Waveform
8/20µs nominal discharge current (In)
Function
Clamps residual voltage from upstream SPDs
Protects against switching surges from motors, transformers, or grid disturbances
LEEYEE Advantage
Example: LY2-C Series
Optimized Voltage Protection Level (Up < 1.5kV)
Type 3 SPD: Point-of-Use Protection (Class III)
Type 3 SPDs provide fine protection for sensitive electronics.
Location
Installed close to equipment (within 5–10 meters)
Test Waveform
Combination Wave
1.2/50µs voltage
8/20µs current
Function
Protects sensitive devices such as:
PLC controllers
Servers
Medical equipment
LEEYEE Advantage
Compact designs
Can be integrated into power sockets or small enclosures
Part II: The Physics of Waveforms – 10/350µs vs 8/20µs
The key technical difference between Type 1 and Type 2 SPDs lies in the test waveform.
10/350µs Waveform (Direct Lightning)
This waveform simulates a direct lightning strike.
Characteristics:
10µs rise time
350µs decay time
Energy Characteristics:
Contains about 20× more energy than an 8/20µs waveform of the same peak current.
Engineering Challenge:
Only true Type 1 SPDs can survive this energy without catastrophic failure.
8/20µs Waveform (Indirect Surge)
This waveform represents indirect lightning effects or switching surges.
Characteristics:
8µs rise time
20µs decay time
Energy Characteristics:
Lower energy than 10/350µs
Occurs much more frequently
Engineering Challenge:
SPDs must withstand thousands of repetitive surge events.
Part III: Comparison Table
| Feature | Type 1 SPD (Class I) | Type 2 SPD (Class II) | Type 3 SPD (Class III) |
|---|---|---|---|
| Primary Test Waveform | 10/350 µs (Iimp) | 8/20 µs (In / Imax) | 1.2/50 µs + 8/20 µs (Uoc) |
| Installation Point | Service Entrance / Main Board | Sub-distribution Boards | Point of Use |
| Protection Goal | Direct Lightning Strikes | Indirect Lightning / Switching | Sensitive Electronics |
| Energy Capacity | Extremely High | Medium to High | Low |
| Mandatory If | Building has lightning rods | Recommended for most installations | Critical electronics protection |
| LEEYEE Series | LY1-D, LY1-B | LY2-C, LY2-B | LY3-D |
Part IV: Coordination & Cascading – The 10 Meter Rule
A common mistake is installing only a Type 1 SPD and assuming the entire building is protected.
Surge protection must be layered.
Why Coordination Matters
If Type 1 and Type 2 SPDs are installed too close together:
Type 2 SPD may trigger first
It will attempt to absorb high-energy lightning current
This can destroy the device instantly
Coordination Distance
Recommended rule:
Maintain at least 10 meters of cable distance between Type 1 and Type 2 SPD.
Reason:
Cable inductance creates impedance
Ensures Type 1 SPD activates first
Type 1+2 Combined SPD
In compact installations where 10 meters is not possible:
LEEYEE provides Type 1+2 combined SPDs
Advantages:
Internal coordination
Compact modular design
Handles both direct and indirect surges
Part V: B2B Sourcing Advantage – The LEEYEE Difference
For professional buyers, supplier reliability is critical.
Risk Mitigation
LEEYEE provides:
Authentic Certification
TUV
CB
CE
SAA
All certificates are verifiable.
PICC Global Insurance
All products are insured by People’s Insurance Company of China (PICC).
Benefits:
Financial protection
Liability coverage for distributors
Supply Chain Transparency
We support:
Factory audits
Production inspection reports
Testing videos
Production Capacity
Manufacturing strength:
8,000 m² factory
8 production lines
Stable delivery capability
Quality assurance:
Professional surge testing equipment
Strict batch inspection procedures
Part VI: Procurement Guide – 5 Red Flags When Buying SPDs
Professional buyers should watch for the following risks.
1. Fake Type 1 Claims
If a supplier claims Type 1 SPD but only provides 8/20µs data, it is not a real Type 1 device.
Always demand 10/350µs (Iimp) test data.
2. No Thermal Protection
Low-quality SPDs may lack thermal disconnectors.
Risk:
MOV overheating
Potential fire hazard
3. High Voltage Protection Level
If Up > 2.5kV for a 230V system, protection may be insufficient.
Recommended:
Up < 1.5kV
4. Fake Certificates
Always verify:
Certificate number
Certification body database
Avoid suppliers providing only logos without documentation.
5. No Product Liability Insurance
Without insurance, distributors bear all risk of product failure.
LEEYEE provides PICC product liability coverage.
Frequently Asked Questions (FAQ)
Do I need a Type 1 SPD if I don’t have a lightning rod?
Usually no.
If there is no external lightning protection and no overhead lines, Type 2 SPD at the main board is typically sufficient.
However, for critical infrastructure, Type 1+2 combined SPDs are recommended.
What is the difference between Iimp and Imax?
Iimp
Used for Type 1 SPD
10/350µs waveform
Simulates direct lightning
Imax
Used for Type 2 SPD
8/20µs waveform
Simulates indirect surges
Can I use only a Type 1 SPD?
No.
Type 1 SPDs handle energy, but residual voltage may remain high.
A Type 2 SPD downstream is required to clamp voltage further.
How often should SPDs be replaced?
Most SPDs include status indicators.
Green: normal
Red: replace
Inspection is recommended:
Annually
After major lightning events
LEEYEE SPDs allow modular replacement without rewiring.
What is a 3+1 SPD configuration?
In a 4-pole SPD:
Three MOVs protect L1, L2, L3 to Neutral
One Gas Discharge Tube (GDT) protects Neutral to Earth
This configuration is recommended for TT and TN-S systems.
Does LEEYEE support OEM / ODM?
Yes.
We offer free customization services, including:
Logo printing
Product color
Packaging design
Helping distributors build their own private brand.
Conclusion
Choosing the correct SPD type is a small investment that prevents catastrophic electrical failure.
By partnering with LEEYEE Electrics, distributors gain access to:
Advanced surge protection technology
Authentic international certifications
Reliable manufacturing capacity
Contact us today to discuss wholesale cooperation and private label opportunities.
