What it is and what the ratings mean
The Siemens 5SU1656-0KV06 is a combination FI/LS protector (RCBO) — a single module that packs both overcurrent protection and residual current protection into a 70 mm wide, 1+N-pole package. The 'Type AC' designation means it detects sinusoidal AC residual currents only; it's the standard choice for general-purpose circuits where pulsed or DC fault currents aren't expected. The 6 A B-curve thermal-magnetic trip handles short-circuit and overload protection for lighting or small motor loads, while the 300 mA rated residual current (IΔn) provides earth-fault protection — typically specified for circuits feeding socket outlets or fixed equipment in commercial or residential distribution boards. The 6 kA rated short-circuit breaking capacity (Icn) means the device can safely interrupt a fault current up to 6 kA at its rated voltage without welding its contacts or failing catastrophically. That's adequate for most domestic and light commercial installations where the prospective short-circuit current at the board is under 6 kA. The B-curve characteristic (3–5 In magnetic trip) suits predominantly resistive or lightly inductive loads like lighting circuits, small pumps, or control transformers — it avoids nuisance tripping from inrush while still clearing a hard short fast enough to protect the cable.
Sourcing and lifecycle
Pricing and availability are confirmed at quote time against an RFQ. Because this is a current-production Siemens RCBO, lead times typically track the factory build cycle — no unusual supply constraints are expected for this standard 6 A / 300 mA variant. Submit an RFQ for a firm delivery commitment.
Where it fits in the panel
At 70 mm width (four modular spaces on a DIN rail), the 5SU1656-0KV06 occupies a standard 1+N-pole slot in a consumer unit or sub-distribution board. The neutral pole is switched and protected — the device opens both line and neutral on a fault, which is the requirement for TN-S and TT earthing systems. The Type AC residual current detection is the entry-level class; if the downstream load includes VFDs, LED drivers, or other electronics that generate pulsed or high-frequency leakage, a Type A or Type F device would be needed instead.