Surge protection device (SPD) insert T1+T2 8/50 412302

Replaceable insert for T1+T2 surge protective devices

The Legrand surge protective device insert is a replaceable module designed for use with the ON 300 series surge protective devices in a T1+T2 configuration (class B+C). The product is a consumable component—worn during operation—that can be quickly replaced without the need to dismantle the entire device from the distribution board.

Compatibility and purpose

The module fits all versions of T1+T2 surge protective devices with an impulse current of 8 kA/pole, specifically reference numbers 412250, 412251, 412253, 412256 and 412257. Depending on the base device variant, the insert supports single-, two-, three-, or four-pole configurations—in both single-phase (1P) and three-phase with neutral (3P+N) systems.

The product is intended for electrical installations without an external lightning protection system (LPS), where the building is supplied by an overhead line. Surge protective devices in this class protect against indirect atmospheric surges and against current surges occurring during switching in the power grid.

Operating parameters and protection

The insert performs two protective functions in one module:

• Type 1 (T1) - protects against direct lightning current strikes with 10/350 µs parameters; the rated impulse current is 8 kA/pole.
• Type 2 (T2) - protects against operational (switching) surges with 8/20 µs parameters; the nominal discharge current is 20 kA/pole, and the maximum is 50 kA/pole.

The maximum continuous operating voltage (Uc) is 320 VAC for L-N and L-PE paths and 255 VAC for the N-PE path. The protection level Up on the L-N path with a T1 wave shape reaches 1.2 kV, while with a T2 wave shape it is 1.7 kV. On the N-PE path, the protection level is 1.5 kV.

The design based on varistors ensures a fast response time—below 25 ns for L/N paths and approximately 100 ns for the N-PE path.

Status signaling and handling

The module is equipped with an optical indicator informing about the technical status of the insert. Green indicates the device is functional; orange signals the need to replace the insert. A tilt lever mounted on the insert facilitates its removal from the surge protective device base during service work.

The insert is mounted on a TH-35 mm DIN rail and occupies the width of one module, fitting on an EN 60715 standard mounting rail. The enclosure protection rating is IP20.

The product complies with EN/IEC 61643-11 standards, which define the requirements for surge protective devices in low-voltage installations.