Siemens 5SN6120-7CP — 1-pole MCB, 6 kA / 15 kA, C-curve
The Siemens 5SN6120-7CP is a 1-pole miniature circuit breaker from the SENTRON 5SN series, with a C tripping characteristic. It carries a 6 kA breaking capacity per EN 60898 and a 15 kA rating per IEC 60947-2 — the higher IEC figure is the one that governs SCCR coordination in industrial panels where the upstream transformer can deliver more fault current. Rated 400 V AC at 50 Hz for multi-phase operation, with a maximum of 440 V AC; DC rating tops out at 72 V.
The 6 kA (EN 60898) figure is the standard for residential and light commercial distribution boards; the 15 kA (IEC 60947-2) rating qualifies it for industrial control panels where fault levels are higher. The 18 mm width and 70 mm installation depth mean it occupies one modular unit on a DIN rail — same footprint as the 5SY and 5SL series, so it drops into an existing panel without busbar or gland-plate rework. The 35 mm² solid conductor capacity handles the larger feed conductors typical of a sub-distribution board.
Temperature range and environment
Rated for -40 °C to +75 °C ambient — wide enough for unheated electrical rooms or outdoor enclosures in temperate climates. The 1.7 W power loss per pole at rated current in hot operating state is modest; no forced cooling needed in a standard IP20 distribution board.