Finder 7P.03.8.255.S007 – 7P Series Surge Protection Devices

Why Choose the Finder 7P.03.8.255.S007 Type 1+2 Surge Protection Device?

The Finder 7P.03.8.255.S007 is a professional Type 1+2 combined lightning and surge protection device (SPD) designed for three-phase 230/400 V AC TN-C electrical distribution systems. Part of the Finder 7P Series, this surge arrester provides coordinated protection against transient overvoltages caused by lightning activity and electrical switching events.

Engineered for installation on a 40 mm busbar system, the Finder 7P.03.8.255.S007 features a 7.5 kA lightning impulse current rating per pole (10/350 µs), a 20 kA nominal discharge current (8/20 µs) and a voltage protection level of 1.5 kV. Its combined Type 1 and Type 2 protection makes it suitable for installation at the boundary between lightning protection zones LPZ 0 and LPZ 1, where incoming electrical supplies require protection against lightning currents and transient surges.

Designed for three-phase TN-C networks with L1, L2, L3 and PEN conductors, this combined surge arrester features replaceable protection modules, visual condition indicators and a module retention system. These features support straightforward inspection and servicing in electrical distribution boards and suitable incoming supply installations.

The Finder 7P.03.8.255.S007 is particularly suitable for professional electrical installations where Type 1+2 surge protection, compact busbar mounting and dependable lightning current discharge capability are essential.

Key Advantages

• Combined Type 1+2 surge protection addresses both lightning impulse currents and transient overvoltages.
• 7.5 kA lightning impulse current per pole provides protection against specified 10/350 µs lightning current impulses.
• 20 kA nominal discharge current supports repeated surge discharge under standard 8/20 µs test conditions.
• 1.5 kV voltage protection level helps limit transient overvoltages reaching downstream electrical equipment.
• 255 V AC maximum continuous operating voltage suits the specified phase-to-PEN protection arrangement.
• 230/400 V AC three-phase system compatibility supports common low-voltage distribution networks.
• Dedicated TN-C network design provides protection for L1, L2 and L3 relative to PEN.
• 40 mm busbar mounting supports integration into compatible electrical distribution assemblies.
• Replaceable protection modules allow servicing without replacing the entire assembly where appropriate.
• Visual condition indicators provide a straightforward means of checking module status.
• Module retention system helps maintain secure installation of the protection modules.
• Suitable for LPZ 0 to LPZ 1 boundaries in correctly designed lightning protection systems.
• IP20 enclosure protection supports installation within suitable electrical distribution equipment.
• −40 to +80 °C operating temperature range supports demanding indoor electrical installations.
• Compact three-module-width format helps conserve space within compatible distribution equipment.
• No remote signalling contact provides a straightforward local visual monitoring arrangement.

Key Features

• Finder 7P Series surge protection device.
• Type 7P.03 combined lightning and surge arrester.
• Exact manufacturer part number: 7P.03.8.255.S007.
• SPD classification: Type 1+2.
• Electrical network: Three-phase TN-C.
• System conductors: L1, L2, L3 and PEN.
• Protection arrangement: 3+0.
• Nominal network voltage: 230/400 V AC.
• Maximum continuous operating voltage (Uc): 255 V AC.
• Lightning impulse current (Iimp): 7.5 kA per pole, 10/350 µs.
• Nominal discharge current (In): 20 kA, 8/20 µs.
• Voltage protection level (Up): 1.5 kV.
• Replaceable surge protection modules.
• Optical status indication.
• Integrated module retention arrangement.
• 40 mm busbar mounting.
• Three-module-width construction.
• IP20 protection rating.
• −40 to +80 °C operating ambient temperature range.
• No integrated remote signalling contact.
• No integrated upstream backup fuse.
• Designed for installation in suitable electrical distribution equipment.
• Suitable for protection zone transitions from LPZ 0 to LPZ 1.

Combined Type 1 and Type 2 Surge Protection

The Finder 7P.03.8.255.S007 combines two important surge protection functions in a single assembly.

Type 1 protection is designed to discharge specified lightning impulse currents, represented by the standard 10/350 µs waveform. This is particularly important at the incoming electrical supply where lightning currents may enter the installation.

Type 2 protection addresses transient overvoltages caused by induced lightning effects and electrical switching operations. These surges are commonly assessed using the 8/20 µs current waveform.

By combining Type 1 and Type 2 protection, the Finder 7P.03.8.255.S007 provides a coordinated protective function suitable for the relevant electrical installation and lightning protection design.

The device is intended for use at the boundary between lightning protection zones LPZ 0 and LPZ 1, where surge protection is commonly required to manage incoming transient energy.

Correct surge protection design should also consider the installation's earthing arrangement, available prospective short-circuit current, conductor lengths and the sensitivity of downstream equipment.

7.5 kA Lightning Impulse Current per Pole

The Finder 7P.03.8.255.S007 has a specified lightning impulse current rating (Iimp) of 7.5 kA per pole using the 10/350 µs waveform.

This rating describes the device's ability to discharge a standardised lightning impulse current under defined test conditions.

The 10/350 µs waveform represents a high-energy lightning current impulse and is used when assessing Type 1 surge protection devices.

For three-phase TN-C installations, the Finder 7P.03.8.255.S007 provides a protective path for each of the three phase conductors relative to PEN.

The required lightning impulse current rating must be selected according to the building's lightning protection design, exposure and applicable installation standards.

Where a higher impulse current rating is required, the corresponding Finder 7P.03.8.255.S012 variant should be evaluated against the manufacturer's current technical documentation.

20 kA Nominal Discharge Current for Transient Overvoltage Protection

The Finder 7P.03.8.255.S007 provides a 20 kA nominal discharge current (In) using the standard 8/20 µs waveform.

This rating is relevant to the device's Type 2 surge protection function and describes its discharge capability under defined testing conditions.

Transient overvoltages may be generated by lightning-induced disturbances, switching of inductive loads, changes in electrical network conditions and other events affecting the power supply.

These events can produce short-duration voltage spikes that exceed the normal operating voltage of electrical equipment.

By diverting surge current through the protective arrangement, the Finder 7P.03.8.255.S007 helps limit the transient voltage appearing across the protected installation.

The device's effectiveness depends on correct installation, appropriate earthing and suitable coordination with other protective equipment.

1.5 kV Voltage Protection Level

The Finder 7P.03.8.255.S007 has a specified voltage protection level (Up) of 1.5 kV.

This parameter indicates the protective voltage level associated with the device under standardised surge test conditions.

During a transient overvoltage event, the SPD conducts surge current to limit the voltage appearing across the protected conductors.

The 1.5 kV protection level helps reduce the risk of excessive transient voltages reaching connected electrical equipment.

However, the actual voltage experienced by downstream equipment can be influenced by installation conductor lengths, inductive voltage drops and the characteristics of the complete surge protection arrangement.

For sensitive electronic equipment, additional coordinated downstream surge protection may be required.

Designed for Three-Phase TN-C Electrical Networks

The Finder 7P.03.8.255.S007 is designed specifically for three-phase TN-C electrical systems.

In a TN-C arrangement, the protective earth and neutral functions are combined in a single PEN conductor.

The device provides a 3+0 protection configuration, with protective paths associated with the three phase conductors L1, L2 and L3 relative to PEN.

This configuration makes the device suitable for the specified four-conductor incoming supply arrangement.

It is important to distinguish TN-C systems from TN-S and TT installations, which have different neutral and protective conductor arrangements.

The Finder 7P.03.8.255.S007 should not be assumed suitable for TN-S, TT or IT systems. A surge protection device with the appropriate network configuration must be selected for those installations.

40 mm Busbar Mounting for Electrical Distribution Assemblies

A key feature of the Finder 7P.03.8.255.S007 is its design for installation on a 40 mm busbar system.

This mounting arrangement makes the device suitable for compatible electrical distribution assemblies, including applications where surge protection is installed in the incoming supply section.

The compact three-module-width construction helps conserve space within the distribution equipment.

Unlike conventional DIN rail surge protection devices, the Finder 7P.03.8.255.S007 is specifically intended for the relevant busbar mounting arrangement.

Installers should therefore verify the compatibility of the distribution board and busbar system before specifying or ordering the device.

Correct installation is essential to achieve the intended electrical protection and mechanical security.

Replaceable Protection Modules and Visual Status Indication

The Finder 7P.03.8.255.S007 incorporates replaceable surge protection modules, allowing maintenance personnel to service the protection assembly when required.

The device also includes optical condition indicators that provide a local visual indication of module status.

This helps simplify routine inspection of the surge protection system during scheduled electrical maintenance.

An integrated module retention arrangement helps keep the protection modules securely positioned within the assembly.

The Finder 7P.03.8.255.S007 does not include a remote signalling contact. Its condition is therefore monitored locally through the visual indicators unless a separate monitoring arrangement is provided.

Any module replacement or inspection involving access to live electrical equipment must be performed by suitably qualified personnel following the appropriate isolation and safety procedures.

Professional Installation and Electrical Safety Requirements

The Finder 7P.03.8.255.S007 is a protective device intended for installation within suitable electrical distribution equipment.

Installation must be carried out by a qualified electrician familiar with surge protection systems, three-phase electrical distribution and the relevant wiring regulations.

The SPD must be selected and installed with appropriate consideration of the incoming supply arrangement, available fault current, upstream overcurrent protection and earthing system.

Because the device does not incorporate an integrated backup fuse, the need for external backup protection must be determined from the manufacturer's coordination requirements and the installation design.

Connection conductor lengths should be kept as short and direct as practicable to minimise additional voltage drop during surge discharge.

The device has an IP20 protection rating and is intended to be installed within a suitable protective electrical enclosure. It is not designed for direct exposure to rain or other outdoor environmental conditions.

For UK installations, the complete surge protection arrangement should be assessed against the applicable edition of BS 7671 and the manufacturer's current technical documentation.

Typical Applications

• Three-phase TN-C electrical distribution systems.
• Main electrical distribution boards.
• Incoming electrical supply surge protection.
• Industrial electrical distribution assemblies.
• Commercial building electrical installations.
• Industrial manufacturing facilities.
• Electrical switchgear and distribution equipment.
• Power distribution systems with 40 mm busbars.
• Electrical installations requiring combined Type 1+2 protection.
• Lightning protection zone transitions between LPZ 0 and LPZ 1.
• Electrical infrastructure exposed to lightning-related surges.
• Industrial automation power distribution systems.
• Building services electrical distribution.
• Electrical panel manufacturing and refurbishment.
• Professional surge protection system upgrades.