Type 1+2 SPD: What It Means and When to Use It
A Type 1+2 SPD combines Class I lightning-current duty and Class II distribution-level surge protection in one device. It is commonly used at the origin of an installation where both Type 1 and Type 2 protection duties are required.
What Is a Type 1+2 SPD?
A SPD Tipo 1+2 is a combined surge protective device designed to meet both Type 1 and Type 2 test duties. It is used where an installation may be exposed to partial lightning current and also needs distribution-level surge-voltage limitation.
In IEC-style terminology, Type 1 duty is associated with Class I testing and the 10/350 μs impulse current waveform. Type 2 duty is associated with Class II testing and the 8/20 μs discharge current waveform.
A Type 1+2 SPD does not mean “better than every Type 2 SPD” in every project. It means the product has been designed and tested for two different surge protection duties.
How a Type 1+2 SPD Works
A Type 1+2 SPD is designed to respond to both high-energy impulse current and lower-energy distribution surges.
Surge enters the system
A lightning-related impulse or switching surge appears on the power system and raises the voltage above the normal operating level.
SPD conducts surge current
The internal protection elements become conductive and divert surge current toward the bonding or earthing system.
Voltage is limited
The SPD reduces the transient voltage reaching downstream equipment according to its voltage protection level and installation conditions.
Type 1+2 SPD vs Separate Type 1 + Type 2 SPDs
A combined Type 1+2 SPD and a separate Type 1 plus Type 2 arrangement can both be valid. The better choice depends on installation space, project design, coordination requirements and the manufacturer's tested solution.
| Comparison item | SPD Tipo 1+2 | Separate Type 1 + Type 2 |
|---|---|---|
| Basic concept | Two test duties in one combined device | Two separate SPD stages installed and coordinated |
| Panel space | Usually more compact | Usually requires more space |
| Coordination | Internal coordination depends on product design and testing | External coordination must be checked between devices |
| Installation simplicity | Often simpler at one main board location | May allow more flexible stage separation |
| Typical use | Main incoming board with both Type 1 and Type 2 duties | Larger installations with separate protection zones or panel distances |
| Selection risk | Must verify both Iimp and Type 2 ratings | Must verify distance, coordination and protection level between stages |
When Do You Need a Type 1+2 SPD?
Type 1+2 SPDs are commonly considered when Type 1 lightning-current duty and Type 2 distribution protection are both needed at the same point.
When Is a Type 2 SPD Enough?
Not every installation needs a Type 1+2 SPD. A Type 2 SPD may be enough where Type 1 lightning-current duty is not required and the installation mainly needs distribution-level surge protection.
A Type 2 SPD may be considered when:
- The project does not require Type 1/Class I duty;
- No partial lightning current is expected at the installation origin;
- The building does not have external lightning protection requiring Type 1 SPD selection;
- The applicable standard, design or risk assessment only requires Type 2 protection;
- The SPD is installed in a sub-distribution board or equipment panel.
How to Select a Type 1+2 SPD
Select a Type 1+2 SPD by checking the full rating set, not only the kA value printed on the product.
| Selection item | Initial direction |
|---|---|
| System type | Confirm AC, PV DC, telecom, signal or special application. |
| Nominal voltage | Choose Uc or Ucpv according to the real operating voltage and system arrangement. |
| Installation position | Confirm whether it is installed at the origin, main board or another protection zone transition. |
| Earthing system | Confirm TN-S, TN-C, TT, IT or the relevant PV DC grounding arrangement. |
| Iimp | Check impulse current rating for Type 1/Class I duty. |
| In and Imax | Check discharge current ratings for Type 2/Class II duty. |
| Su | Check whether the voltage protection level is suitable for downstream equipment. |
| Short-circuit rating | Verify prospective short-circuit current and required backup protection. |
| Poles and protection mode | Confirm 1P, 2P, 3P, 4P, N-PE or PV pole configuration. |
Installation and Coordination Notes
Keep leads short
Long connection conductors increase residual voltage. Keep SPD connection paths as short and straight as practical.
Check backup protection
Verify required fuse or breaker coordination according to the SPD datasheet and project short-circuit conditions.
Coordinate downstream
A Type 1+2 SPD at the main board may not eliminate the need for downstream Type 2 or Type 3 protection near sensitive equipment.
AC Type 1+2 SPD vs PV DC Type 1+2 SPD
AC and PV DC SPDs are not interchangeable. A Type 1+2 classification must still be matched with the correct application and voltage system.
| Comparison item | AC Tipo 1+2 SPD | PV DC Type 1+2 SPD |
|---|---|---|
| Applicazione | Low-voltage AC distribution system | Photovoltaic DC circuits and inverter DC side |
| Voltage rating | Uc selected for AC system voltage | Ucpv selected for PV string or array voltage |
| Arc behaviour | AC current naturally crosses zero | DC current requires PV-specific disconnection design |
| Common use | Main incoming boards and AC distribution panels | PV combiner boxes, inverter DC input and PV protection panels |
| Selection warning | Match earthing system and protection mode | Do not use ordinary AC SPD on PV DC circuits |
Common Type 1+2 SPD Selection Mistakes
Choosing by kA only
A high current number is not enough. Check waveform, rating type, Uc, Up, protection mode and short-circuit conditions.
Ignoring Iimp
If Type 1 duty is required, the Iimp rating and 10/350 μs test duty must be checked, not only Imax.
Using AC SPD on PV DC
PV DC circuits require PV-specific voltage and disconnection characteristics. AC products should not be substituted.
Forgetting downstream panels
A main-board Type 1+2 SPD may still need downstream coordinated SPDs when loads are far away.
Wrong earthing assumption
Protection mode and pole configuration must match the actual TN, TT, IT or PV grounding arrangement.
No backup protection check
The SPD and upstream protective device must be compatible with the prospective short-circuit current.
Type 1+2 SPD Support from LEEYEE
LEEYEE is a specialized surge protection and low-voltage protection supplier, trusted for solar PV, power distribution, telecom, industrial, and OEM applications.
Model selection
Support for selecting AC or PV DC Type 1+2 SPD by system voltage, pole configuration, protection mode and project environment.
OEM and project supply
Support for OEM labels, project documentation, packaging and bulk supply for distributors, contractors and equipment builders.
Application documents
Support with datasheets, product images, installation references and basic selection communication for B2B buyers.
Type 1+2 SPD FAQ
What does Type 1+2 SPD mean?
Type 1+2 SPD means a surge protective device tested for both Type 1/Class I and Type 2/Class II duties. It can handle lightning-current impulse duty and distribution-level surge protection in one device.
Is Type 1+2 SPD the same as Type 1 SPD?
No. A Type 1 SPD is tested for Type 1 duty, while a Type 1+2 SPD is tested for both Type 1 and Type 2 duties. The actual product ratings must still be checked.
Is Type 1+2 SPD better than Type 2 SPD?
Not always. Type 1+2 is suitable when Type 1 duty is required. If the installation only needs distribution-level surge protection, a correctly selected Type 2 SPD may be enough.
Where is a Type 1+2 SPD installed?
It is commonly installed at the origin of the installation or in the main distribution board, depending on the system design and protection concept.
Does a Type 1+2 SPD remove the need for downstream SPDs?
Not always. Long cable runs, downstream distribution boards and sensitive equipment may still require coordinated Type 2 or Type 3 protection.
Can an AC Type 1+2 SPD be used on PV DC circuits?
No. PV DC circuits require PV-specific SPDs with suitable DC voltage and disconnection characteristics.
What information is needed to select a Type 1+2 SPD?
Provide AC or DC application, nominal voltage, earthing system, installation position, poles, required Iimp, In or Imax, Up, short-circuit conditions and project quantity.
Need Help Selecting a Type 1+2 SPD?
Send your AC or PV DC application, system voltage, earthing arrangement, installation position, poles, required ratings and project quantity. LEEYEE will help identify a suitable Type 1+2 surge protection option.