What this MCB is and what the ratings mean
The Siemens 5SY6004-7CC is a SENTRON miniature circuit breaker (MCB) in a 1P+N configuration — it switches both line and neutral, but only the line pole has overcurrent protection. The neutral pole is switched only, not protected. Rated 4 A at 230 V AC with a C tripping characteristic, meaning it holds 4 A continuously and trips instantaneously between 5 and 10 times rated current (20–40 A). That C-curve is the standard choice for general-purpose loads like lighting, small transformers, and control circuits where inrush isn't extreme. Breaking capacity is 6 kA per EN 60898, which covers most residential and light commercial service-entrance faults. Overvoltage category III means it's rated for fixed-installation use downstream of the main distribution board, not for equipment-level protection.
Panel fit and integration
Snaps onto standard DIN rail (35 mm), occupies 1 width unit (18 mm), and can be mounted in any position. Installation depth is 70 mm; overall depth is 76 mm. IP20 with connected conductors — fine inside a closed panel, not for wet or dusty environments. Sealable, halogen-free, silicon-free. Touch protection is built in. The neutral conductor is switched internally, so no separate neutral bar is needed for this branch. Terminal positions are not combined top/bottom, meaning line and load each have dedicated terminals.
Environmental and compliance
Rated for ambient temperatures from -40 °C to +75 °C, which covers unheated enclosures and outdoor-adjacent installations. Vibration-resistant per IEC 60068-2-6. Energy limiting class 3 — limits let-through energy during a fault, which helps with downstream device coordination. The part is halogen-free and silicon-free, relevant for environments sensitive to outgassing (clean rooms, certain industrial processes).