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  • New item   Surge protective device Type 1+2 (B+C) | 1P | Iimp 5 kA (10/350) | Imax 50 kA | Up ≤ 1.5 kV | IP20 | SCHELINGER A51-SPD01-1P-B+C

    Surge protective device Type 1+2 (B+C) | 1P | Iimp 5 kA (10/350) | Imax 50 kA | Up ≤ 1.5 kV | IP20 | SCHELINGER A51-SPD01-1P-B+C

    Code: A51-SPD01-1P-B+C
    Barcode: 5900280916631
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    SCHELINGER A51-SPD01-1P-B+C is a modular Type 1+2 (B+C) surge protective device with plug-in varistor modules. Iimp 5 kA (10/350 µs) per pole, In 20 kA, Imax 50 kA, Up ≤ 1.5 kV. Suitable for the incoming or main board.

  • Product description

    Surge protective device Type 1+2 (B+C) | 1P | Iimp 5 kA (10/350) | Imax 50 kA | Up ≤ 1.5 kV | IP20 | SCHELINGER A51-SPD01-1P-B+C

    SCHELINGER A51-SPD01-1P-B+C is a modular Type 1+2 (B+C) surge protective device with plug-in varistor modules. Iimp 5 kA (10/350 µs) per pole, In 20 kA, Imax 50 kA, Up ≤ 1.5 kV. Suitable for the incoming or main board.

    Key point:
    A Type 1+2 SPD at the incomer diverts partial lightning current coming in on the line or through the building earthing to earth and limits the overvoltage in the installation. It is the first stage – sensitive circuits often still need Type 2 or Type 3 after it.
    Class
    Type 1+2 / Class I+II / B+C
    Iimp (10/350 µs)
    5 kA
    Up
    ≤ 1.5 kV
    Configuration
    1P

    Operating principle

    The SPD is mounted on a DIN rail in the main incoming switchboard, as close to the supply entry as possible, and connected in parallel: the phases (and N) go to the SPD terminals, the common terminal goes to the main earthing terminal. A backup fuse rated to the manufacturer's limit is installed upstream of the SPD.

    Under normal conditions the varistor conducts practically no current. When a surge arrives, its resistance drops within nanoseconds and the partial lightning current (10/350 µs) or switching impulse (8/20 µs) is diverted to earth.

    The voltage left in the installation does not exceed Up (≤ 1.5 kV for this model), which the switchboard devices can withstand. An overheated or worn module disconnects from the supply and the indicator turns red.

    What does SCHELINGER A51-SPD01-1P-B+C do for you?
    At the supply entry, SCHELINGER A51-SPD01-1P-B+C handles partial lightning currents up to 5 kA per pole and limits surges to ≤ 1.5 kV – this is the first and most important protection stage; without it, T2 and T3 SPDs in sub-distribution boards may not withstand a direct or nearby lightning strike.

    Technical specifications

    Product type Surge protective device Type 1+2
    Manufacturer / model SCHELINGER A51-SPD01-1P-B+C (EAN 5900280916631)
    Class (IEC / EN 61643-11) Type 1+2 / Class I+II / B+C
    Poles / configuration 1P – single pole; build the scheme from several units (e.g. L–PE and N–PE for single-phase TN-S)
    Nominal voltage Un 230 V AC
    Max. continuous operating voltage Uc 275 V AC
    Impulse current Iimp (10/350 µs) 5 kA
    Nominal discharge current In (8/20 µs) 20 kA
    Max. discharge current Imax (8/20 µs) 50 kA
    Voltage protection level Up ≤ 1.5 kV
    Terminals up to 35 mm², comb busbar possible
    Status indication Window: green – OK, red – replace module
    Protective element High-energy varistor (MOV), plug-in module
    Mounting DIN rail 35 mm
    Degree of protection IP20
    Operating temperature −40…+70 °C
    Dimensions (D × H × W) 68 × 90 × 18 mm

    Main functions

    • Partial lightning current diversion – Iimp 5 kA (10/350 µs) per pole when lightning strikes the building or a nearby line.
    • Switching surge limitation – In 20 kA and Imax 50 kA (8/20 µs) – against network switching, motors and transformers.
    • Voltage protection level Up ≤ 1.5 kV – for switchboard devices and equipment with a withstand rating of 2.5 kV or higher.
    • Thermal disconnector – a worn varistor disconnects from the supply reducing the fire risk.
    • Status indicator – green / red shows whether the module is still protecting.
    • Plug-in modules – a tripped module is pulled out and replaced; the base and wiring stay in place.

    Wiring diagram – 2 × 1P – single-phase TN-S supply

    2 × 1P – single-phase TN-S supply – SCHELINGER A51-SPD01-1P-B+C | elsprendimai.eu
    ☝ Click the diagram to open an enlarged version.
    ⚠ The diagram is for guidance only and may contain inaccuracies. Before wiring, check it against the manufacturer's instructions and the markings on the device.
    The qualified electrician carrying out the installation is responsible for it. UAB "Elektrotechnikos sprendimai" is not liable for the connection or any errors.

    Most common wiring mistakes

    ✗ Long leads to the SPD and PE Each extra metre adds about 1 kV to Up – the protection no longer works. Total lead length – up to 0.5 m.
    ✗ SPD downstream of a standard RCD The discharge current flows through the RCD – it trips or gets damaged. The SPD goes upstream of the RCD or downstream of an S-type RCD.
    ✗ 4P (4+0) in a TT network The L–PE fault current of a damaged varistor is too low to blow the fuse – voltage remains on enclosures. For TT networks – "3+1" only.
    ✗ PE to the nearest terminal, not to the bar A path through other devices' terminals adds inductance and dangerously raises the voltage in the switchboard. PE goes straight to the main earthing terminal.
    ✗ Only T2 in a building with a lightning protection system A T2 SPD is not designed for partial lightning current (10/350 µs) and may explode. With a lightning protection system, the supply entry needs T1+T2.

    How does it differ from similar models?

    Where is it used?

    • Main incoming switchboard of a private house supplied by an overhead line
    • Buildings with a lightning protection system (LPS) – supply entry or main switchboard
    • Farm, warehouse and production buildings with long lines
    • Heat substations, pumping stations, boiler houses
    • AC side of a solar PV plant – the switchboard where the inverter is connected
    • Switchboards for communication, security and video surveillance systems
    • Separate buildings supplied by cable from the main building
    • Switchboard manufacturing and upgrades according to a lightning protection design

    Selection and installation

    • Pick the scheme by network type: TN-C – 3P between L and PEN, TN-S – 4P (4+0), TT – only "3+1" with an N–PE spark gap.
    • With an external LPS the value depends on the lightning protection level (LPL): LPL III–IV usually needs 12.5 kA per pole, LPL I–II needs more – we will calculate it.
    • Choose 5–8 kA per pole models where there is no LPS and the threat comes through an overhead line.
    • Install the SPD at the incomer upstream of the RCD (or after an S-type RCD) so that the discharge current does not pass through the RCD.
    • Backup fuse – within the manufacturer limit; if the incoming fuse is larger, give the SPD its own fuse (e.g. 125 A gG).

    Use by need

    For the homeowner.
    One row of DIN modules at the supply entry protects the boiler, heat pump, inverter and household appliances against surges arriving during thunderstorms.
    For the electrician.
    Clear diagrams for TN-C, TN-S and TT networks, plug-in modules – easy to install and service after a storm.
    For the designer.
    Declared Iimp, In, Imax and Up values to IEC / EN 61643-11 – can be specified in the lightning protection design and coordinated with T2 / T3.

    Practical application

    If a rural property is supplied by an overhead line and the boiler controller or router fails after every thunderstorm, install a T1+T2 SPD in the main incoming switchboard upstream of the RCD with short leads to the earthing bar, and add a T2 or T3 stage next to the sensitive electronics.

    Pros

    • Combined T1+T2 protection in one device
    • Iimp (10/350 µs) value stated in the manufacturer data
    • Up ≤ 1.5 kV – suits standard switchboard devices
    • Thermal disconnector and status indication
    • Plug-in modules – repair without disconnecting wires
    • Lower price than 12.5 kA models when there is no lightning protection system

    Cons / limitations

    • Does not replace T2 / T3 protection for switchboards far from the supply entry and for sensitive electronics
    • Iimp 5 kA per pole – usually too low for a building with a lightning protection system; choose a 12.5 kA model
    • Single pole – a complete configuration requires several units

    ⚡ Safety and installation notes

    • Install only with the supply disconnected; verify the absence of voltage on all poles.
    • Connect the SPD upstream of the residual current device (RCD) or downstream of an S-type RCD.
    • PE conductor to the main earthing terminal – not smaller than 16 mm² Cu, as short as possible and without loops.
    • Backup fuse rating – according to the manufacturer's limit; if the incoming fuse is larger, provide a separate fuse for the SPD.
    • Before insulation resistance testing, pull out the modules or disconnect the SPD.
    • Work must be carried out by a qualified electrician; check the indicators after a storm.
    ☝ From experience
    • A single-phase TN-S incomer needs two 1P units: L–PE and N–PE. A three-phase TN-S needs four. A ready 4P version with a common busbar is often more convenient.
    • Keep the leads to the SPD and from it to PE as short as possible – total length up to 0.5 m. Every extra metre adds about 1 kV to Up and the protection loses its point.
    • Run the PE conductor straight to the main earthing bar, not through other devices' terminals. In a Type 1 circuit use at least 16 mm² Cu.
    • Pull out the modules or disconnect the SPD before an insulation resistance test (500–1000 V) – otherwise the tester shows "leakage" and the modules may be damaged.
    • Check the indicator after every storm and at least once a year. Keep a spare module on site – replacement takes a minute: isolate only the SPD backup fuse or MCB, the rest of the board can stay in service.
    • If the sub-boards are more than 10 m away or feed sensitive electronics, add a separate Type 2 or Type 3 SPD there – the incomer alone is not enough.
    ☝ Elsprendimai.eu recommends: With the SPD you will need fuses and fuse holders for backup protection, an equipotential bonding bar for earthing, and for sub-distribution boards and sensitive electronics – T2 and T3 SPDs. The T1+T2 selection guide helps you plan the whole system.

    Quick selection guide

    Type 1+2 / Class I+II / B+C
    5 kA
    ≤ 1.5 kV
    1P

    Suitable when you need:

    • To protect the supply entry when the building has a lightning protection system or is supplied by an overhead line
    • A single-device T1+T2 stage in the main switchboard
    • Clear Iimp, In and Up values for design or acceptance

    Check before use:

    • The earthing system: TN-C, TN-S or TT – the configuration depends on it
    • Whether there is a lightning protection system and its lightning protection level (LPL) – Iimp depends on it
    • The incoming fuse rating and space in the switchboard for short leads

    Important reminder: A T1+T2 SPD at the supply entry does not replace the lightning protection system, earthing, or T2 / T3 protection in remote switchboards – it is only the first stage.

    FAQ

    Is a Type 1+2 SPD at the incomer enough on its own?
    For a small house with all boards next to the incomer it often is. If there are sub-boards more than 10 m away, a PV inverter, a boiler room with electronics or a server room – add Type 2 or Type 3 there.
    What if the indicator turns red?
    The module has done its job and no longer protects. Replace it with a module of the same series – the base and wiring stay.
    When do I need 12.5 kA and when is 5–8 kA enough?
    If the building has an LPS – 12.5 kA per pole or more according to the LPL. Without an LPS, when the house is fed by an overhead line, 5–8 kA per pole is usually enough; 5 kA suits lower-risk sites with a short service line.
    Which wire should be used for connection?
    For the phases – the same or a smaller cross-section than the supply, but not smaller than the manufacturer's minimum; for PE – at least 16 mm² Cu, both as short as possible.
    Does the SPD need its own separate earth electrode?
    No, it is connected to the main earthing terminal, to which the building's earth electrode and equipotential bonding are connected.
    How long does an SPD last?
    It depends on the number of storms and the size of the surges; replace the module when the indicator turns red, and check it after every severe storm.
    Not sure which one to choose? See the Type 1+2 SPD selection guide or contact us – we will select it from your board diagram.

    Documents and sources

    Checked 2026-10-17.

    Surge protective device Type 1+2 (B+C) | 1P | Iimp 5 kA (10/350) | Imax 50 kA | Up ≤ 1.5 kV | IP20 | SCHELINGER A51-SPD01-1P-B+C

    SCHELINGER A51-SPD01-1P-B+C – T1+T2 (B+C) surge protective device for the main incoming switchboard: Iimp 5 kA, Imax 50 kA, Up ≤ 1.5 kV. Protects the installation against partial lightning currents and switching surges.

    Illustrative image may have been created using AI. The appearance of the product may differ slightly from the image shown. Please refer to the technical specification.

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