Type 1 vs Type 2 vs Type 3 SPD: Complete IEC 61643-11 Guide (2026)
Quick Answer: Type 1 vs Type 2 vs Type 3 SPD
Type 1, Type 2, and Type 3 SPD (also called Class I, Class II, Class III) are the three surge protective device types defined in IEC 61643-11, each covering a different installation point and surge energy level. Type 1 SPD — the type 1 surge protection device or type 1 surge protective device — installs at the service entrance to handle direct lightning current (10/350 µs, Iimp 12.5–50 kA). Type 2 SPD — the type 2 surge protector or type 2 surge protective device — is required at every distribution board (8/20 µs, In 5–20 kA). Type 3 SPD — the type 3 surge protector — is a point-of-use add-on for sensitive equipment only; it cannot be used standalone and always requires an upstream Type 2.
The 10/350 µs waveform carries 10–20× more energy than 8/20 µs at the same peak current — which is why Type 1 and Type 2 are not interchangeable, and why installing a Type 2 where a Type 1 is needed causes catastrophic failure.
The types of surge protective devices defined in IEC 61643-11 — Type 1, Type 2, and Type 3 SPD — represent three different protection levels in a coordinated cascade system. Understanding the difference between Type 1 vs Type 2 vs Type 3 SPD is the starting point for every correct surge protection specification in IEC markets. Each type handles a specific surge threat at a specific location; none can substitute for another.
| Parameter | Type 1 SPD (Class I) Lightning current arrester |
Type 2 SPD (Class II) Surge arrester / distribution SPD |
Type 3 SPD (Class III) Point-of-use SPD |
Type 1+2 Combined |
|---|---|---|---|---|
| IEC 61643-11 Class | Class I | Class II | Class III | Class I + II |
| Test waveform | 10/350 µs | 8/20 µs | 1.2/50 µs + 8/20 µs (combination) | 10/350 µs AND 8/20 µs |
| Key current parameter | Iimp = 12.5–50 kA | In = 5–20 kA / Imax = 20–40 kA | Imax ≤ 5–10 kA | Iimp 12.5–25 kA + In/Imax |
| Up (voltage protection level) | ≤ 4.0 kV (OVC III) | ≤ 2.5 kV (OVC II) | ≤ 1.5 kV (OVC I) | ≤ 2.5–4 kV |
| LPZ boundary | LPZ 0A/0B → LPZ 1 | LPZ 1 → LPZ 2 | LPZ 2 → LPZ 3 | LPZ 0A/0B → LPZ 1 |
| Installation point | Main distribution board (MDB) / service entrance | Sub-distribution boards, every panel | Socket outlet / equipment terminal | MDB / service entrance |
| Standalone use | ✅ Yes | ✅ Yes — baseline for all facilities | ❌ Requires upstream Type 2 | ✅ Yes |
| Cascade distance to next stage | ≥ 10 m cable between each stage — or decoupling inductor (≥ 10 µH) if < 10 m — per IEC 61643-12 | |||
Most common mistake: Installing only a Type 2 SPD at the main panel of a building with an external lightning protection system (LPS) or overhead supply lines. A Type 2 surge protective device is rated for 8/20 µs only — when direct lightning current (10/350 µs) enters via an overhead line or LPS bonding conductor, the Type 2 absorbs 10–20× its rated energy and fails immediately. IEC 60364-5-53 and IEC 62305-4 require Type 1 at the LPZ 0→1 boundary in these cases.
What Is an SPD? Meaning, Electrical Definition, and Classification
SPD stands for Surge Protective Device — the official IEC 61643-11 term used in the Type 1 vs Type 2 vs Type 3 SPD classification to describe any device that limits transient overvoltages and diverts surge currents to protect connected equipment. The SPD electrical meaning covers all panel-mounted transient suppressors connected in parallel with the load on low-voltage power systems (up to 1,000 V AC or 1,500 V DC). An SPD does not interrupt the supply during normal operation — it activates only when voltage exceeds its maximum continuous operating voltage (Uc).
The meaning of SPD in electrical systems is sometimes confused with surge strips or plug-in suppressors — these are consumer-grade Type 3 products. Electrical SPD as defined by IEC 61643-11 refers specifically to panel-installed protection devices classified by Type (1, 2, or 3). In North America, the equivalent term under UL 1449 is TVSS (Transient Voltage Surge Suppressor) — the type 1 TVSS, type 2 TVSS, and type 3 designations map directly to IEC classes. For any IEC market project, always specify by Type rather than generic "surge protector."
Class I / II / III vs Type 1 / 2 / 3 — same thing: IEC 61643-11 uses both "Class" (I, II, III) and "Type" (1, 2, 3) terminology for the same classification. Older datasheets say "Class I SPD" (also written "spd class 1"); current IEC 61643-11 editions say "Type 1 SPD." The devices and test requirements are identical. The SPD class designations Class I, Class II, and Class III have not changed — only the labelling convention differs between editions.
Type 1, Type 2 and Type 3 SPD: What Each Type Does
Type 1 SPD — Class I — Service Entrance
Also called: type 1 surge protector, type 1 surge protection device, type 1 surge protective device, Class I SPD, lightning current arrester, type 1 spds
Waveform: 10/350 µs (direct lightning current)
Current: Iimp 12.5–50 kA per phase
Up: ≤ 4.0 kV (OVC III equipment withstand)
Install: Main distribution board (MDB), LPZ 0→1 boundary
Mandatory when: External LPS present; overhead supply lines
Type 2 SPD — Class II — Distribution Board
Also called: type 2 surge protector, type 2 surge protection device, type 2 surge protective device, Class II SPD, surge protective device type 2, spd type 2
Waveform: 8/20 µs (induced surges + switching transients)
Current: In 5–20 kA / Imax 20–40 kA
Up: ≤ 2.5 kV (OVC II equipment withstand)
Install: Every sub-distribution board, LPZ 1→2 boundary
Required: All facilities — minimum baseline SPD level
Type 3 SPD — Class III — Point of Use
Also called: type 3 surge protector, surge protector type 3, Class III SPD, surge protective device type 3, point-of-use SPD
Waveform: 1.2/50 µs + 8/20 µs combination wave
Current: Imax ≤ 5–10 kA
Up: ≤ 1.5 kV (OVC I equipment withstand)
Install: Socket outlet, equipment terminal, rack PDU
Rule: Never standalone — always requires upstream Type 2
What Is a Type 1 SPD? (Class I / IEC 61643-11)
A type 1 SPD — also referred to as a type 1 surge protection device, type 1 surge protective device, or Class I SPD — is the only IEC 61643-11 device class tested with the 10/350 µs lightning current waveform. This is the standardised waveform that replicates direct lightning current — with a much longer energy tail than the 8/20 µs waveform used for Type 2 and Type 3 testing. At the same peak current, a 10/350 µs impulse carries 10–20 times the total energy of an 8/20 µs impulse.
Type 1 SPD is mandatory when: (1) the building has an external lightning protection system with air terminals per IEC 62305-3; (2) the building is supplied by overhead power lines. In both cases, IEC 60364-5-53 and IEC 62305-4 require a Type 1 surge protective device at the LPZ 0→1 boundary. Buildings with underground supply only and no external LPS may be protected by Type 2 at the MDB, subject to risk assessment per IEC 60364-4-44.
Type 2 cannot substitute for Type 1 where Type 1 is required. A Type 2 surge protective device will absorb 10–20× its rated thermal energy when exposed to 10/350 µs lightning current. Immediate, catastrophic failure — at the moment protection is most needed.
What Is a Type 2 SPD? (Class II / IEC 61643-11)
A type 2 SPD — also called a type 2 surge protector, type 2 surge protection device, or Class II SPD — is the most widely installed surge protective device class and the baseline requirement for all commercial, industrial, and residential electrical installations. It is tested with the 8/20 µs waveform and handles both indirect lightning surges and switching transients generated within the building (motors, VFDs, transformers, HVAC systems).
A surge protective device type 2 installs at every distribution board in the building — not only at the main panel. Each sub-distribution board is a separate LPZ 1→2 boundary requiring its own Type 2. If budget allows only one SPD investment, Type 2 at every distribution board is always the priority over Type 3.
Key parameters for type 2 surge protection selection: specify In ≥ 20 kA for main distribution boards in commercial and industrial installations; In ≥ 5–10 kA for smaller residential sub-boards. Always check Uc matches the earthing system — 275 V for TN-S, higher for TT.
What Is a Type 3 SPD? (Class III / IEC 61643-11)
A type 3 SPD — also called a type 3 surge protector, surge protector type 3, or Class III SPD — provides the final stage of protection directly at sensitive electronic equipment. It is tested with the combination wave (1.2/50 µs + 8/20 µs) and achieves Up values of 0.8–1.5 kV — lower than a Type 2 can deliver alone, matching the OVC I impulse withstand (1.5 kV) of sensitive electronics.
A surge protective device type 3 can never operate independently. Its maximum discharge capacity (Imax 3–10 kA) is far below the energy of a real building-level surge. Without an upstream Type 2 absorbing the bulk of the energy first, even a moderate surge will destroy the Type 3 — along with the equipment it was meant to protect.
Type 2 vs Type 3 SPD: Key Differences
| Parameter | Type 2 SPD (Class II) | Type 3 SPD (Class III) |
|---|---|---|
| Installation point | Sub-distribution boards | Socket outlet / equipment terminal / rack PDU |
| Imax | 20–40 kA (8/20 µs) | ≤ 5–10 kA (combination wave) |
| Up | ≤ 2.5 kV (OVC II) | ≤ 1.5 kV (OVC I) |
| Standalone? | ✅ Yes — baseline for all installations | ❌ No — always needs upstream Type 2 |
| Typical application | Factory sub-panel, commercial distribution board, MCC | Server rack PDU, PLC cabinet, medical instrument, CNC controller |
10/350 µs vs 8/20 µs: Why the Waveform Defines the Type
| Parameter | 10/350 µs — Type 1 SPD | 8/20 µs — Type 2 & Type 3 SPD |
|---|---|---|
| Rise time / half-value time | 10 µs rise, 350 µs to 50% | 8 µs rise, 20 µs to 50% |
| Relative energy (same peak current) | 10–20× higher | Baseline |
| Origin | Direct lightning strikes, overhead line entry | Switching transients, indirect/conducted lightning |
| Component requirement | Larger spark gap + MOV — higher thermal mass | Compact DIN-rail MOV module |
| Typical device cost vs Type 2 | 2–4× higher | Baseline |
Why this energy difference matters in practice: The 10/350 µs waveform has the same peak as an 8/20 µs waveform but a far longer tail — energy flows for much longer. At the same peak, a 10/350 µs impulse delivers 10–20× more thermal energy to the MOV. A Type 2 SPD exposed to a 10/350 µs lightning current event receives far more energy than its thermal mass can absorb — immediate destructive failure is the result. This is why Type 1 SPDs are physically larger, more expensive, and use spark gap + MOV technology rather than MOV alone.
Iimp, In, Imax: Understanding SPD Discharge Current Ratings
| SPD Type | Current Parameter | Typical Range (IEC LV systems) | Definition |
|---|---|---|---|
| Type 1 SPD only | Iimp — Impulse discharge current | 12.5–50 kA per phase | Peak 10/350 µs current the SPD withstands per IEC 61643-11; the defining Type 1 parameter |
| Type 2 SPD | In — Nominal discharge current | 5–20 kA | 8/20 µs current at which SPD is tested for 15 operations without degradation |
| Type 2 SPD | Imax — Maximum discharge current | 20–40 kA | Single-shot 8/20 µs maximum without permanent damage |
| Type 3 SPD | Imax — Maximum discharge current | 3–10 kA | Combination wave maximum — much lower energy capacity than Type 2 |
Do not confuse Iimp with Imax: Iimp uses the 10/350 µs waveform (Type 1 only); Imax uses the 8/20 µs waveform (Type 2 and Type 3). A Type 1 with Iimp = 25 kA and a Type 2 with Imax = 25 kA are not equivalent — the Type 1 handles 10–20× more energy per event despite the same peak number.
Voltage Protection Level (Up) and IEC 60664-1 Equipment Coordination
In the Type 1 vs Type 2 vs Type 3 SPD hierarchy, Up — the voltage protection level — is the maximum voltage appearing across the SPD terminals during conduction at its rated test current. It must be below the equipment's impulse withstand voltage per IEC 60664-1 Overvoltage Category (OVC). The three SPD types cover the three OVC levels relevant to IEC low-voltage installations:
| OVC (IEC 60664-1) | Impulse withstand — 230 V system | Typical equipment | SPD required |
|---|---|---|---|
| OVC IV | 6 kV | Service entrance, utility meters | Upstream of SPD system |
| OVC III | 4 kV | Distribution boards, switchgear, industrial loads | Type 1 (Up ≤ 4 kV) |
| OVC II | 2.5 kV | Motors, appliances, standard industrial equipment | Type 2 (Up ≤ 2.5 kV) |
| OVC I | 1.5 kV | Sensitive electronics, IT equipment, instrumentation | Type 3 (Up ≤ 1.5 kV) |
For complete parameter guidance covering Uc, In, Imax, response time, and Up selection together, see the SPD key parameters guide.
Lightning Protection Zones (LPZ) and SPD Type Assignment
The Type 1/2/3 classification maps directly to the Lightning Protection Zone (LPZ) framework in IEC 62305-4. Each LPZ is an electromagnetic protection level separated by boundaries where SPDs reduce the surge environment to progressively lower levels.
| LPZ Boundary | SPD Type | Installation Point | Surge level handled |
|---|---|---|---|
| LPZ 0A/0B → LPZ 1 | Type 1 (Class I) | MDB / service entrance | Direct lightning partial current, 10/350 µs |
| LPZ 1 → LPZ 2 | Type 2 (Class II) | Sub-distribution boards | Residual surges after Type 1, switching transients, 8/20 µs |
| LPZ 2 → LPZ 3 | Type 3 (Class III) | Equipment terminal / socket / PDU | Residual low-energy transients, combination wave |
Cascade Coordination: The 10 m Rule, Decoupling, and Type 1+2 Combined
When Type 1 and Type 2 SPDs are installed in series, the Type 1 must activate first. Without adequate cable separation, the lower-clamping-voltage Type 2 fires first and absorbs full 10/350 µs lightning energy it was never rated for — catastrophic failure results.
IEC 61643-12 specifies three solutions to ensure correct activation sequence:
- ≥ 10 m of cable between Type 1 and Type 2 — provides ~10 µH of natural inductive decoupling ensuring correct activation sequence
- Decoupling inductor (≥ 10 µH) — placed in series between the two devices when physical separation is impossible; achieves the same inductive impedance in compact form
- Type 1+2 combined SPD at the entrance — both stages factory-coordinated in a single device, eliminating the sequencing problem entirely
Lead length rule — the most commonly violated installation requirement: Total SPD connection conductor length (line side + PE side combined) must not exceed 0.5 m per IEC 61643-12. Each additional metre adds ~1 µH of inductance — at 20 kA with 1 µs rise time, 1 m of excess lead adds ~20 kV of additional voltage at the equipment. Neatly routing SPD leads to the top busbar from a bottom-mounted device can easily add 2 m and render the protection almost completely ineffective.
Type 1+2 Combined SPD — When to Use It
A type 1+2 combined SPD (also called type 1 2 surge protector or Type 1+2 SPD) passes both IEC 61643-11 Class I and Class II tests simultaneously in a single DIN rail device. Use it when:
- Panel space is insufficient for separate Type 1 + Type 2 devices
- Distance between service entrance and first sub-board is under 10 m — separate cascade coordination is physically impossible
- Retrofitting an existing panel to full IEC 61643-11 compliance in one step
Limitation: Typical Iimp for combined devices is 12.5–25 kA per pole — lower than the highest-rated dedicated Type 1 devices. For very high lightning exposure sites (LPL I per IEC 62305), a dedicated Type 1 with higher Iimp may still be required. Browse TrilPeak's Type 1+2 combined SPD range.
Earthing System Impact on SPD Selection (TN-S, TT, TN-C, IT)
| Earthing system | SPD mode (3-phase) | Uc | N–PE element | Key rule |
|---|---|---|---|---|
| TN-S | 3+1 | 275 V | Required — same Uc | Standard for most IEC commercial/industrial |
| TT | 4+0 | 275–320 V phase; up to 440 V N–PE | Required — higher Uc | Higher N–PE Uc essential — standard 275 V fails prematurely under TT fault conditions |
| TN-C | 3+0 (L–PEN only) | 275 V L–PEN | Never — shorts PEN conductor | No N–PE element anywhere in TN-C section |
| IT | 3+0 (L–PE only) | ≥ 440 V L–PE | Not applicable | Uc must cover phase-to-earth voltage in first fault condition |
For full pole-count and Uc selection guidance by earthing system, see the single phase vs three phase SPD selection guide.
When Is Type 1 SPD Mandatory? IEC Requirements
| Installation condition | Type 1 required? | IEC reference |
|---|---|---|
| Building has external LPS (air terminals per IEC 62305-3) | ✅ Mandatory | IEC 60364-5-53, IEC 62305-4 |
| Overhead power supply lines | ✅ Required / strongly recommended | IEC 60364-4-44, national IEC 60364 implementations |
| Underground supply only, no external LPS | ⚠️ Risk assessment — Type 2 often sufficient | IEC 60364-4-44, IEC 62305-2 |
| Hospital, data centre, critical infrastructure | ✅ Typically mandatory per national standards | HD 60364 and regional equivalents |
| High lightning density (> 5 flashes/km²/year) | ✅ Risk assessment typically requires Type 1 | IEC 62305-2 |
Real-World Application: Data Centre Three-Stage Cascade
Data centres illustrate the full types of surge protection cascade in practice. A commercial surge protector system at this scale requires coordination across all three levels — and protection on both power and signal paths.
- Zone 1 — MDB / Service Entrance: Type 1 SPD or Type 1+2 combined, Iimp ≥ 12.5 kA — handles direct lightning and utility-side surges at LPZ 0→1
- Zone 2 — UPS / Sub-distribution: Type 2 SPD, In ≥ 20 kA — absorbs UPS switching transients and residual energy
- Zone 3 — Server Rack PDU: Type 3 SPD, Imax ≥ 5 kA, Up ≤ 1.5 kV — final clamping for OVC I electronics
- Signal paths: Ethernet / RS-485 / coaxial SPDs on all data lines — a surge entering an unprotected data port bypasses all upstream power SPDs
For the full data centre lightning protection specification, see the data centre surge protection guide.
TrilPeak manufactures IEC 61643-11 certified SPDs — Type 1, Type 2, Type 3, Type 1+2 combined, and DC SPDs for solar, EV and BESS. In-house MOV production, factory-direct pricing, OEM/ODM available.
Frequently Asked Questions: Type 1 vs Type 2 vs Type 3 SPD
The type 1 vs type 2 spd difference comes down to waveform and installation point. A type 1 surge protection device (Class I, IEC 61643-11) installs at the service entrance and is tested with the 10/350 µs direct lightning waveform at Iimp 12.5–50 kA. A type 2 surge protective device (Class II) installs at distribution boards and is tested with the 8/20 µs induced surge waveform at In 5–20 kA. The 10/350 µs waveform carries 10–20× more energy than 8/20 µs at the same peak — which is why a Type 2 cannot substitute for a Type 1 where direct lightning current is present, and why Type 1 SPDs cost 2–4× more.
SPD stands for Surge Protective Device — the official IEC 61643-11 term for any panel-mounted device that limits transient overvoltages and diverts surge current to protect connected equipment. The SPD electrical meaning covers all three IEC types: Type 1 (Class I), Type 2 (Class II), and Type 3 (Class III). In North America, the equivalent is TVSS (Transient Voltage Surge Suppressor) per UL 1449 — the type designations are the same. The term electrical SPD and electric SPD both refer to the same IEC 61643-11 classification. Always specify by IEC Type for industrial, commercial, and solar applications rather than the generic consumer term "surge protector."
IEC 61643-11 defines three types of surge protective devices in the Type 1 vs Type 2 vs Type 3 SPD classification for AC low-voltage power systems: Type 1 SPD (Class I) at the service entrance for direct lightning protection (10/350 µs, Iimp up to 50 kA); Type 2 SPD (Class II) at distribution boards for induced surges and switching transients (8/20 µs, In 5–20 kA); and Type 3 SPD (Class III) at point-of-use for sensitive electronics (combination wave, Imax ≤ 10 kA). A fourth variant, the Type 1+2 combined SPD, meets both Class I and Class II requirements in a single device. For DC systems (solar PV, EV charging, BESS), IEC 61643-31 defines equivalent DC surge protection device types.
No — a type 3 surge protector must never be used standalone per IEC 61643-11. It is only rated for Imax = 3–10 kA at combination wave. Without an upstream Type 2 absorbing the bulk of the surge energy first, even a moderate surge event will destroy the Type 3 immediately. The surge protective device type 3 is a final-stage fine-clamping supplement — not a primary protector. Always install Type 2 at the distribution board first, then add Type 3 for sensitive equipment.
A type 1+2 combined SPD (also called type 1 2 surge protector) is a single DIN rail device certified to both IEC 61643-11 Class I (Iimp 10/350 µs) and Class II (In/Imax 8/20 µs). Use it when panel space is limited, when the distance between service entrance and first sub-board is under 10 m, or when retrofitting an existing panel. Typical Iimp is 12.5–25 kA per pole — lower than dedicated Type 1 devices, so extreme exposure sites may still need a dedicated Type 1. The key advantage: since both stages are factory-coordinated, the 10 m cascade distance requirement is eliminated at that installation point.
Per IEC 61643-12, approximately 10 metres of cable must separate a Type 1 SPD from a downstream Type 2. This cable provides ~10 µH of inductive decoupling at surge frequencies, ensuring the Type 1 activates first and absorbs the bulk of the lightning energy before the voltage wave reaches the Type 2. Without this separation, the Type 2 fires first and absorbs 10/350 µs energy it was never rated for — catastrophic failure.
When 10 m is impossible, use a decoupling inductor (≥ 10 µH) between the devices, or use a Type 1+2 combined SPD at the entrance to eliminate the coordination problem entirely. The same principle applies between Type 2 and Type 3 (recommended ≥ 5–10 m).
For buildings with underground supply only and no external LPS, a Type 2 SPD at the main distribution board is typically sufficient per IEC 61643-11 — subject to risk assessment per IEC 60364-4-44. However, if the building has an LPS with air terminals per IEC 62305, or if overhead lines are present anywhere in the upstream supply chain, a type 1 surge protection device is mandatory at the service entrance. When in doubt, install a Type 1+2 combined SPD — it satisfies both requirements in one device.
Iimp (impulse current) — Type 1 SPD only, 10/350 µs waveform, 12.5–50 kA. The defining Type 1 parameter. In (nominal discharge current) — Type 2 SPD, 8/20 µs, 5–20 kA. The SPD handles this current for 15 operations without degradation per IEC 61643-11. Imax (maximum discharge current) — Type 2 and Type 3, 8/20 µs, single-shot maximum. Type 2: 20–40 kA; Type 3: 3–10 kA. Critical: Iimp and Imax use different waveforms and are not comparable despite using the same kA units — a Type 1 with Iimp 25 kA handles far more energy than a Type 2 with Imax 25 kA.
The earthing system determines SPD pole count and Uc — regardless of whether you need Type 1 or Type 2. TN-S: 3+1 mode, Uc = 275 V for all elements. TT: 4+0 mode, Uc up to 440 V for the N–PE element (TT systems develop higher N–PE temporary overvoltages during earth faults). TN-C: 3+0 only — no N–PE element permitted. IT: L–PE protection only with Uc ≥ line-to-line voltage. The most dangerous error: using a 3+0 SPD in a TN-S or TT building, leaving the neutral-to-earth surge path completely unprotected.
A type 1 surge protective device costs 2–4× more than a Type 2 because it requires: larger spark gap and MOV components rated for the 10/350 µs waveform carrying 10–20× more energy than 8/20 µs; specialist impulse test equipment for 10/350 µs certification; and reinforced enclosures designed to handle direct lightning energy. Every internal component must be sized for the full 10/350 µs thermal load — not just the peak current.
Replace any SPD immediately if the status indicator shows fault (red LED or blown cartridge) or physical damage is visible. Typical service life: 10–15 years in low-surge environments; 3–5 years at industrial sites, coastal zones, or high-lightning regions. Inspect the status indicator after every major lightning event. TrilPeak SPDs feature plug-in replaceable cartridges and dry-contact status output for remote monitoring. See the full inspection checklist in the guide on when to replace a surge protector.
Conclusion
The type 1 vs type 2 vs type 3 spd decision comes down to where you are in the building and what surge level you face: Type 1 (Class I) at the service entrance for direct lightning; Type 2 (Class II) at every distribution board as the non-negotiable baseline; Type 3 (Class III) at sensitive equipment as the fine-clamping final stage. Get the cascade coordination right — the 10 m rule, correct Uc for the earthing system, and 0.5 m maximum lead length — and the three types work together to protect the full installation from OVC IV at the grid connection down to OVC I at the equipment terminals.
Standards Referenced
- International Electrotechnical Commission. (2025). IEC 61643-11:2025 — Low-voltage surge protective devices — Part 11: Surge protective devices connected to AC low-voltage power systems (2nd ed.). IEC. https://webstore.iec.ch/en/publication/65314
- International Electrotechnical Commission. (2020). IEC 61643-12:2020 — Selection and application principles (3rd ed.). IEC. https://webstore.iec.ch/en/publication/32531
- International Electrotechnical Commission. (2019). IEC 62305-4:2010+AMD1:2019 — Protection against lightning — Part 4: Electrical and electronic systems within structures. IEC. https://webstore.iec.ch/en/publication/6847
- International Electrotechnical Commission. (2020). IEC 60664-1:2020 — Insulation coordination for equipment within low-voltage supply systems — Part 1. IEC. https://webstore.iec.ch/en/publication/63385
- International Electrotechnical Commission. (2016). IEC 60364-5-53:2013+AMD1:2016 — Low-voltage electrical installations — Part 5-53. IEC. https://webstore.iec.ch/en/publication/1586
Related Resources
- Type 1 SPD Range — IEC 61643-11 Class I, Iimp 12.5–50 kA, single and three-phase
- Type 2 SPD Range — IEC 61643-11 Class II, In 20–40 kA, DIN rail
- Type 3 SPD Range — point-of-use, Up ≤ 1.5 kV
- Type 1+2 Combined SPD — Iimp 12.5–25 kA, factory-coordinated
- All AC Surge Protectors — complete range by phase and earthing system
- IEC 61643-11 Standard Explained — Uc, In, Imax, Iimp, Up guide
- SPD Key Parameters: Clamping Voltage, MCOV, In/Imax & Response Time
- Circuit Breaker vs Surge Protector — SCPD selection per IEC 61643-12
- SPD Installation Guide — lead length rule, V-connection, SCPD placement
- Single Phase vs Three Phase SPD Selection — pole count and Uc by earthing system
- What Is a Lightning Protection System? — IEC 62305, LPZ concept
- Lightning Arrester vs Surge Arrester — external LPS vs internal SPD
- SPD Selector Tool — correct model in 60 seconds
TrilPeak manufactures IEC 61643-11 certified SPDs with in-house MOV production — Type 1, Type 2, Type 3, Type 1+2, and DC SPDs for solar, EV and BESS. Factory-direct pricing, OEM/ODM available, 7–15 day lead time.
