Siemens 5SD7444-8KK11 Combined Surge Protective Device Type 1+2, 4-Pole, 300 V AC

Combined surge protective device (SPD) Type 1+2 for protecting low-voltage installations against surges caused by direct lightning strikes and switching operations. Its spark gap and varistor technology safely limits overvoltages and diverts high impulse currents to ground, ensuring continuous availability of connected equipment.

Advantages

Compact 4-pole design (3+N) in only 4 TE width saves space on the DIN rail. The device combines Type 1 and Type 2 protection in a single unit, eliminating the need for separate arresters and simplifying installation. High discharge capacity of 12.5 kA per pole (10/350 µs) and low voltage protection level < 1.5 kV provide reliable protection for sensitive electronics.

Suitable for

• Main distribution boards in residential and commercial buildings
• Industrial power supply systems requiring lightning protection equipotential bonding
• Protection of downstream surge protective devices (Type 2 and Type 3)
• Installations with TN-S and TT earthing systems

Key specifications

• SPD type: Type 1+2 (Class B+C)
• Maximum continuous operating voltage Uc: 300 V AC
• Nominal voltage: 230/400 V AC
• Impulse current Iimp (10/350 µs): 12.5 kA per pole
• Nominal discharge current In (8/20 µs): 20 kA
• Voltage protection level Up: < 1.5 kV
• Short-circuit withstand capability: 50 kA
• Connectable conductor cross-section: 1.5–35 mm² solid, 1.5–25 mm² stranded
• Mounting: 35 mm DIN rail
• Module width: 4 TE (72 mm)

Recommendations

Install this SPD at the origin of the electrical installation to achieve lightning protection equipotential bonding. Ensure proper earthing and follow local regulations. For optimal protection, coordinate with downstream Type 2 and Type 3 surge protective devices.