The difference between a 1P+N SPD and a 2P SPD cannot always be determined from the product name. For a correct single-phase distribution-board order, buyers must verify the real protection topology, earthing system, protection modes, base and cartridge combination, label and certificate scope.
Índice
Quick Answer: 1P+N SPD or 2P SPD?
A 1P+N SPD and a 2P SPD are not always electrically different. The names may describe the product format, while the real circuit may be 1+1/CT2 or 2+0/CT1. For TT or TN-S boards, verify the circuit diagram, protection modes and approved earthing-system scope before ordering.
A verified 1+1/CT2 SPD is a common purchasing direction for many 230/240 V single-phase TT boards and for TN-S projects requiring L–N plus N–PE protection. A verified 2+0/CT1 product may also be appropriate where the project specifically requires separate L–PE and N–PE protection paths.
The terms 1P+N and 2P are also used for MCBs, RCBOs, RCDs and isolators. SPD terminology relates to surge protection paths and product construction, not overcurrent protection or circuit-breaker switching logic.
1P+N or 2P may describe poles, modules or the commercial format shown in the catalogue.
1+1/CT2 or 2+0/CT1 identifies the actual surge protection paths.
The circuit diagram, earthing system and rated protection modes must agree.
What Is a 1P+N SPD?
A 1P+N SPD is a single-phase surge protective device intended for systems containing a phase conductor, neutral and protective earth. The description normally indicates that the product is designed around the phase and neutral conductors rather than two unrelated phases.
Many products sold as 1P+N use a 1+1 or CT2 circuit: one protection path between L and N and another between N and PE. However, the wording “1P+N” alone does not prove the internal component arrangement. Buyers must still check the manufacturer's circuit diagram.
What Is a 2P SPD?
A 2P SPD usually means a two-pole, two-module or two-position surge protective device. Some 2P products use separate L–PE and N–PE protection paths, commonly described as 2+0 or CT1.
Other products carrying “2P” in the model name use a 1+1 circuit instead. Therefore, 2P does not automatically mean 2+0. It also does not mean “Type 2”; pole count and SPD test classification are different specifications.
Separate the Product Name from the Protection Topology
Catalogue terminology varies between manufacturers. Two products may both occupy two DIN modules and look similar while using different internal circuits. Conversely, products called 1P+N and 2P may use the same 1+1 protection concept.
| Termo | What it usually describes | O que isso não prova | Required buyer check |
|---|---|---|---|
| 1P+N SPD | A phase-plus-neutral single-phase product format | The exact internal protection circuit | Request the basic circuit diagram |
| 2P SPD | Two poles, modules or product positions | That the product is necessarily 2+0 | Confirm every declared protection mode |
| 1+1 / CT2 | L–N protection followed by N–PE protection | The Type, Uc, Up or discharge-current ratings | Check ratings for both protection paths |
| 2+0 / CT1 | L and N independently protected toward PE | Suitability for every TT or TN installation | Check system and installation-position approval |
| DUP tipo 2 | An SPD test classification | The number of poles or internal topology | Keep Type classification separate from 2P |
Ask the supplier to state whether the complete assembly is 1+1/CT2 or 2+0/CT1 and to identify the L–N, L–PE and N–PE protection modes.
1+1 SPD vs 2+0 SPD: Internal Protection Paths
The internal topology determines how surge current is diverted. It is more important to engineering selection than the number of modules visible from the front of the product.
1+1 / CT2 protection
A typical 1+1 design contains a voltage-limiting element between L and N and a switching element such as a GDT or spark gap between N and PE. The exact component technologies must be confirmed for the selected model.
2+0 / CT1 protection
A typical 2+0 design provides separate surge paths from L to PE and from N to PE. Component technology, leakage current and TOV behaviour depend on the actual design and cannot be inferred from the word “2P”.
Published Example: Why “2P” Does Not Always Mean 2+0
One officially published single-phase SPD carries “2P” in its product designation while the manufacturer describes its electrical arrangement as a 1+1 configuration for TT and TN systems.
This example demonstrates why buyers should verify the official circuit diagram and protection modes instead of interpreting “2P” as automatic proof of a 2+0 topology.
View the third-party manufacturer reference
Third-party product information is cited only to illustrate variation in industry terminology. LEEYEE is not affiliated with, sponsored by or endorsed by the referenced manufacturer.
1P+N SPD vs 2P SPD: Buyer Comparison
| Comparison point | Product called 1P+N | Product called 2P | Correct purchasing action |
|---|---|---|---|
| Product naming | Usually phase plus neutral | Usually two poles or two modules | Do not approve from naming alone |
| Possible topology | Frequently 1+1/CT2 | May be 1+1/CT2 or 2+0/CT1 | Request the circuit diagram |
| Protection paths | Often L–N and N–PE | May be L–PE and N–PE or L–N and N–PE | Check protection modes individually |
| TT application | Commonly selected when verified as CT2 | Depends on topology and RCD position | State TT and RCD position in the RFQ |
| TN-S application | Suitable where the approved design requires L–N plus N–PE | CT1 and CT2 versions may both exist | Follow the project protection-mode requirement |
| N–PE component | Frequently a GDT or spark gap in 1+1 products | Depends on the actual circuit | Confirm technology and mode rating |
| Cartridges | Phase and N–PE modules may be different | Modules may be identical or different | Verify individual spare-module codes |
| Uc and Up | May be specified for L–N and N–PE | May be specified for L–PE and N–PE | Compare values by protection mode |
| Certificate scope | Must cover the complete base and cartridge combination | Must cover the exact complete assembly | Match the certificate, label and BOM |
| Principal risco | Assuming every 1P+N product has the same circuit | Assuming every 2P product is 2+0 | Approve topology before mass production |
Why the Protection Topology Matters
L–N protection
Most single-phase loads operate between L and N. A direct L–N protection mode can therefore be important when evaluating the voltage protection level seen by downstream equipment.
L–PE and N–PE protection
Common-mode surges must also be diverted toward the equipotential bonding system. The complete protection level depends on the circuit and the length and routing of the installation conductors.
RCD coordination
In TT systems, the SPD position relative to the residual current device affects the acceptable connection arrangement and must be included in the selection information.
Replacement control
The L-side module and N–PE module may use different technologies and ratings. Incorrect substitution can create a performance, service and warranty risk.
Which SPD Should You Choose for TT or TN-S?
Single-Phase TT System
For many 230/240 V TT boards, especially where the SPD is installed upstream of the main RCD, a verified 1+1/CT2 SPD is a common purchasing direction.
- Confirm L–N and N–PE protection modes.
- Confirm the N–PE switching element and its ratings.
- State whether the SPD is upstream or downstream of the RCD.
- Check TOV behaviour and manufacturer application instructions.
- Follow the applicable national installation rules.
Single-Phase TN-S System
TN-S projects may use CT1 or CT2 products depending on the required protection paths, installation design and manufacturer's approved application.
- Use 1+1/CT2 where L–N plus N–PE protection is required.
- Use 2+0/CT1 where L–PE plus N–PE protection is specified.
- Do not assume that one topology is universal for every TN-S board.
- Compare Uc, Up and TOV data for the actual protection modes.
- Match the final choice to the project specification.
Determine whether the SPD is installed before or after PEN separation. After separation, N and PE are separate conductors. Before separation, a generic 1P+N or 2P description is not enough to approve the arrangement.
TT vs TN-S Single-Phase SPD Selection Flow
Use the earthing system, RCD or PEN position and real protection topology as the decision inputs. Do not start with the number of modules shown in a supplier's catalogue.
- Identify the earthing system at the SPD location. Confirm TT, TN-S, TN-C-S or another arrangement at the exact installation point.
- Confirm the RCD or PEN position. State whether the SPD is upstream or downstream of the RCD and before or after PEN separation where applicable.
- Verify the real topology and protection modes. Confirm 1+1/CT2 or 2+0/CT1 and identify L–N, L–PE and N–PE paths.
- Match the ratings and order documents. Check Uc, Up, discharge ratings, base, cartridges, label, datasheet and certificate model scope.
A product label showing only 1P+N or 2P is not sufficient evidence of the internal topology or system suitability.
Which Version Is Better for Distributor Stocking?
The best stock SKU is not simply the product labelled 1P+N or 2P. It is the product with the broadest verified application range, controlled replacement modules and documentation that matches the target markets.
Recommended Core-Stock Profile for Many IEC Markets
- 230/240 V application clearly declared Nominal voltage, frequency and system scope are documented.
- Verified 1+1/CT2 circuit where appropriate L–N and N–PE protection paths are shown in the datasheet.
- TT and TN-S scope stated in writing Do not rely only on a verbal sales statement.
- Pluggable construction Supports replacement-module sales and easier field maintenance.
- Separate module codes L-side and N–PE cartridges can be identified without confusion.
- Mode-specific Uc and Up data Buyers can compare the actual protected paths.
- Backup protection declared Maximum permitted fuse or circuit-breaker conditions are available.
- Complete certificate package The ordered base and cartridge combination is included in the scope.
Compare local mains conditions, customer terminology, earthing systems, TOV requirements and certification expectations in every target market.
What LEEYEE Confirms Before Quotation
Before recommending a single-phase SPD for an OEM, distributor or panel-builder order, the application information should be converted into one controlled product specification.
OEM and Bulk-Order Checklist
A bulk order should not move into label approval or mass production until the system, topology, modules and documentation have been checked against the same complete model.
- System and installation point Confirm voltage, frequency, earthing system, RCD position and PEN separation point.
- Connection scheme Specify 1+1/CT2 or 2+0/CT1 rather than only 1P+N or 2P.
- Protection modes Identify all required L–N, L–PE and N–PE protection paths.
- SPD classification and discharge ratings Confirm Type, In, Imax, Iimp and Itotal where applicable.
- Uc, Up and TOV Check the values for the actual protection modes, not one headline value.
- Short-circuit and backup protection Confirm ISCCR and maximum permitted upstream protection.
- Base and cartridge combination Record exact base, L-module and N–PE-module codes.
- Label and remote contact Approve model, ratings, status indication and NO/NC/COM logic if required.
- Certificate and technical documents Match the ordered assembly to the datasheet, report and certificate scope.
- OEM sample and packaging approval Approve logo, manual, barcode, cartons and spare-module ratio before production.
IEC 61643-11:2025 contains the AC-specific requirements for low-voltage SPDs and is used together with the common requirements in IEC 61643-01:2024. Buyers should confirm the accepted standard edition and transition rules for the destination market and certification scheme.
RFQ Template for a Single-Phase SPD
Use this format to avoid receiving quotations for products that look similar but use different circuits or module combinations.
Copyable Buyer Specification
Application: Single-phase AC distribution board Nominal system voltage: ______ V AC Frequency: 50 / 60 Hz Earthing system at SPD location: TT / TN-S / TN-C-S / Other SPD position: Upstream / downstream of RCD PEN position, if applicable: Before / after separation Required topology: 1+1 CT2 / 2+0 CT1 Required protection modes: L-N / L-PE / N-PE SPD classification: Type 2 / Type 1+2 Uc by protection mode: ____________________ Up by protection mode: ____________________ In: ______ kA Imax: ______ kA Iimp or Itotal, if applicable: ______ kA TOV requirement: _________________________ ISCCR: ______ kA Maximum backup protection: _______________ Construction: Pluggable / fixed DIN width: ______ modules / ______ mm Base model: ______________________________ L module model: __________________________ N-PE module model: _______________________ Remote contact: Required / not required Required certificate or standard: _________ OEM label requirements: __________________ Packaging requirements: __________________ Order quantity: __________________________
Four Common Purchasing Mistakes
A product with 2P in its model name may still use a 1+1 circuit.
SPD protection paths are not the same as MCB switching or overcurrent poles.
TT and TN-C-S selection cannot be completed without the installation point.
A high Imax cannot correct the wrong topology, Uc, Up, TOV or certificate scope.
Perguntas mais frequentes
Is a 1P+N SPD the same as a 2P SPD?
Not necessarily. Both products may occupy two DIN modules, and some manufacturers use the descriptions for similar products. The internal circuit may be 1+1/CT2 or 2+0/CT1, so the circuit diagram must be checked.
Does every 1P+N SPD use a 1+1 circuit?
Many 1P+N products use L–N plus N–PE protection, but buyers should not assume this without checking the declared protection modes and circuit.
Does 2P mean Type 2 SPD?
No. 2P normally describes the poles or product format. Type 2 is an SPD test classification. One product may be both 2P and Type 2, but the two terms describe different properties.
Which SPD is commonly selected for a single-phase TT board?
A verified 1+1/CT2 SPD is a common direction for many TT boards, especially upstream of the main RCD. Final selection must follow the actual system, project design, local rules and manufacturer instructions.
Can a TN-S board use either 1+1 or 2+0?
Both topologies may be available for TN-S applications. The correct choice depends on whether the project requires L–N plus N–PE protection or separate L–PE and N–PE protection, together with the approved product data.
What should a buyer request before approving the order?
Request the official circuit diagram, mode-specific Uc and Up values, discharge ratings, TOV data, base and cartridge codes, backup protection instructions and certificate model scope.
Need to Confirm a Single-Phase SPD Before Ordering?
Send LEEYEE the system voltage, earthing system, RCD or PEN position, required topology, ratings, certificate and order quantity. We can help confirm the base, modules, label and OEM documentation before quotation or sample approval.
Technical References
- IEC. IEC 61643-11:2025, requirements and test methods for low-voltage SPDs connected to AC low-voltage power systems. IEC publication page .
- IEC. IEC 61643-01:2024, common requirements and test methods for low-voltage surge protective devices. IEC publication page .
- Phoenix Contact. Lightning and Surge Protection Basics, including CT1, CT2, x+0 and x+1 connection schemes and their application in TN and TT systems. Technical guide .
- Third-party manufacturer product information cited as a published example of a product using “2P” in its designation while being described as a single-phase 1+1 configuration. Accessed for terminology comparison only. Official manufacturer reference .
