Selective main MCB for distribution boards
The Siemens SENTRON 5SP3716-1 is a selective main miniature circuit breaker (MCB) in the 5SP3 design, built for 3-pole, 400 V AC, 50 Hz networks. The E tripping characteristic is the key differentiator here: it's designed for selective (time-delayed) coordination with downstream MCBs. In a fault, the 5SP3716-1 holds long enough for the branch breaker to clear, so only the faulty circuit drops out — not the whole board. This is what makes it a main circuit breaker rather than a branch device. It ships as a factory-assembled unit: three 1-pole breakers mounted on a 5ST1324 adapter with three 5ST1323 protective covers.
For a residential or light commercial board fed from a transformer with typical impedance, 25 kA covers most standard scenarios. Conductor termination accepts 2.5 mm² minimum up to 50 mm² maximum, with saddle terminals. That 50 mm² upper end is generous for a 16 A device — it lets you land the incoming feeder cable without a separate terminal block or reducer. Mechanical service life is 20 000 switching cycles typical. Vibration resistance is 2 g per IEC 60068-2-6 (20 frequency cycles, 5 to 150 to 5 Hz), and shock resistance is 30 g for at least 3 impacts at 11 ms duration. This is robust enough for most fixed installations but not for mobile or high-vibration platforms without additional dampening.
For compliance documentation: the SENTRON series carries CE marking per the Low Voltage Directive and is designed to EN 60898. RoHS and REACH declarations are standard from Siemens for current-production parts. No UL listing is claimed on this variant — it's a European-market design (400 V / 50 Hz, characteristic E), so verify local code acceptance if the panel is destined for a North American installation.
Mounts on 35 mm standard DIN rail per EN 60715, or alternatively on a busbar system or with screw fixing using accessories. The 6 MW width (about 108 mm for a 3-pole assembly) means it takes up a full third of a typical 18-module distribution board — plan the layout accordingly. The switch position indicator shows green for OFF, red for ON, which is helpful during commissioning and troubleshooting. Power supply connection position is any — no top/bottom restriction on this design, which simplifies wiring in tight enclosures. The saddle terminals accept up to 50 mm², so use a torque screwdriver to avoid overtightening on the smaller 2.5 mm² conductors. Depth of 92 mm means it fits standard shallow enclosures, but check the door clearance if a transparent cover is used.