Surge arrester T2 (C) – zero‑leakage ETITEC SM T2 300/20 4+0 002440750

T2 type surge arrester for TN-S installations

This device is designed to protect electrical installations from surges in TN-S networks, where the protective conductor (PE) and neutral (N) are separated from the source. It is primarily intended for installation in residential distribution boards or commercial facilities, where effective second‑level (T2) protection is required – i.e., outside the main distribution board but before the end‑user equipment.

It uses a combination of MOV (metal‑oxide varistor) and GDT (gas discharge tube) technologies, allowing rapid and efficient diversion of high‑energy surge impulses. It does not contain an integrated fuse – circuit protection against device failure depends on the main protective device in the panel.

With a maximum discharge current of 50 kA (8/20 µs) and a rated current of 20 kA, it handles typical lightning strikes and transient network surges. A protection level of 1.5 kV means the voltage on the load terminals will be limited to this value – sufficient for most household and office equipment.

Mounting is on a 35 mm DIN rail, occupying 4 modules. Conductors up to 35 mm² (solid or stranded) and flexible cables up to 25 mm² can be connected, providing flexibility for various cable types – from rigid wires in the panel to flexible leads to equipment.

Operation indication is optical – a red LED on the housing clearly shows that the arrester has acted and needs replacement. There are no remote‑signal contacts, so it cannot be linked to a BMS or building automation system.

An IP20 protection rating makes it unsuitable for outdoor or humid locations – only dry, closed distribution boards. Continuous operating voltage is 300 V AC, allowing safe operation even with slightly elevated network voltages (e.g., 240 V), and its construction is not intended for DC networks or TT/IT systems.

Note: although there is no leakage current, this does not make it “ideal” – every surge arrester ages under repeated impulses. Optical indication is the only way to know when it must be replaced.