The Siemens 5SP3340-3 is a 3-pole SENTRON miniature circuit breaker (MCB) rated 40 A at 400 V AC, 50 Hz, with a 25 kA breaking capacity per EN 60898. Its tripping characteristic E is designed for motor and transformer circuits where inrush currents exceed the B or C curve — it holds through short-duration surges without nuisance tripping, then clears fast on a hard fault. Overvoltage category IV means it's rated for the service entrance, not just downstream subpanels.
Lockout/tagout — this one has it built in
The 5SP3340-3 has an integrated locking slide that accepts a padlock, wire seal, or cable tie. That means positive mechanical isolation — the handle can be locked in the OFF position. No exceptions. If you're specifying for a LOTO program, this saves you from having to add an external lockable handle or a separate disconnect. The switch position indicator shows green for OFF, red for ON — no ambiguity when you're verifying isolation.
Takes up 4.5 width units — plan your enclosure fill accordingly. Infeed can be at the box terminal, and the supply cord position is any orientation — no top-feed restriction. Depth is 76.3 mm, height 128 mm. IP40 with conductors connected, so it's suited for dry indoor panels, not washdown zones.
Survives 30 g shock (11 ms, 3 impacts minimum) and 2 g vibration per IEC 60068-2-6 (20 cycles, 5 to 150 Hz). Surge voltage withstand is 6 kV, insulation voltage 690 V. This is a robust part for industrial panel environments — not just residential.