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Siemens 5SM1646-8FD — Residual Current Breakers (RCCB/RCBO)

Siemens 5SM1646-8FD FI-Protector, Type A, 63A 4P 0.3A 400V,

MPN5SM1646-8FD

Siemens 5SM1646-8FD FI-Protector Type A (PSE/SSF), 55mm, 63A 4-pole, 0.3A IΔn, 400V, 4TE, selective break.

Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Jul 2026

Product details

Selective RCD for earth-fault discrimination

The Siemens 5SM1646-8FD is a Type A FI-Protector (PSE/SSF) rated 63A, 4-pole, with a residual operating current IΔn of 0.3A at 400V. The 4TE width and 55mm depth fit standard DIN-rail distribution boards.

Type A sensitivity and 0.3A threshold

The 0.3A IΔn is higher than the standard 30mA for personal protection — it is sized for equipment protection or fire prevention on circuits with high natural leakage (e.g., long cable runs, VFD-fed motors, or IT equipment). The 63A current rating handles the full load of a sub-main feeder or a large single load.

Integration into a distribution panel

Snap-on mounting to 35mm DIN rail. The 4TE width occupies four modular units — plan for 70mm of rail space. Terminals accept up to 35mm² copper conductors.

Frequently asked questions

What does the Type A and selective break mean on this RCD?

Type A means the device detects both sinusoidal AC and pulsating DC residual currents up to 6mA smooth DC. The selective break (time-delayed) characteristic ensures discrimination: downstream RCDs trip first on a fault, preventing the main RCD from dropping the entire board.

MPN
5SM1646-8FD