What this 1 A C-curve 4-pole MCB is for
The Siemens 5SY7401-7CC is a SENTRON miniature circuit breaker rated 1 A at 400 V AC, with a C tripping characteristic that handles inrush currents up to 5–10× rated before tripping — so it's sized for moderate motor starts or transformer inrush on a panel, not just resistive lighting loads. The 4-pole (4P) version switches all four phases, meaning it's the right fit for a three-phase-plus-neutral feeder in a distribution board where you need coordinated isolation. Breaking capacity is 50 kA per IEC 60947-2 and 5 kA per UL 1077 / CSA C22.2 No.235 — that IEC figure says it can safely interrupt a 50 kA prospective fault current at 400 V without welding contacts or venting arc gas into adjacent gear, which is the spec that matters for industrial panel SCCR compliance.
If your load is purely resistive (heaters, incandescent lighting) a B-curve would trip faster, but for the mix of loads you see on a typical machine feeder, C-curve is the right call. Terminals accept solid or stranded copper from 0.75 mm² up to 35 mm², which covers everything from a 1.5 mm² control circuit up to a 10 mm² feeder. Tightening torque is 2.5–3.5 N·m, standard for this class — no special tooling needed. The 5 kA UL/CSA rating is lower but still covers most North American commercial panels; if you need the full 50 kA for a UL 508A panel, check the specific series variant.
That covers unheated electrical rooms and outdoor enclosures in most climates. It's halogen-free and silicon-free, so it won't outgas corrosive compounds in a sealed enclosure with sensitive electronics. Installation depth is 70 mm (the body is 76 mm deep overall), so you need at least 80 mm of enclosure depth to clear the terminals and wiring space.
The 5SY7401-7CC is a 4-pole C-curve 1 A breaker. If your BOM was built around a 5SY6602-8 (which is a different pole count and rating), this won't drop in without rewiring — pole count and amperage have to match. For a direct functional second-source within the same SENTRON family, the 5SY7140-8CC is a 4-pole C-curve but at a higher current rating; verify your load before substituting.