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Siemens 5SY8303-8 — 3-Pole MCB (DIN Rail)

Siemens 5SY8303-8 SENTRON MCB, 3A D-Curve 3P 50kA

MPN5SY8303-8
Active

Siemens SENTRON 5SY8303-8 miniature circuit breaker, 3-pole, D tripping characteristic, 3 A rated current, 50 kA breaking capacity at 400 V AC per IEC 60947-2, 3 modular width units.

Siemens 5SY8303-8 datasheet (PDF)
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

5SY8303-8 — Identification
ParameterValue
Brand nameSENTRON
Number of poles3
Pole configuration3P
Suitability for operationMechanical engineering / industry
5SY8303-8 — Protection
ParameterValue
Tripping characteristic (curve)D
Breaking capacity per IEC 60947-250 kA
Overvoltage categoryIII
IP protection classIP20, with connected conductors
Pollution degree3
5SY8303-8 — Electrical
ParameterValue
Rated current (AC)3 A
Rated voltage (AC, multi-phase)440 V
5SY8303-8 — Mechanical
ParameterValue
Modular width units3
Mounting positionany
Width54 mm
Height90 mm
Depth76 mm
Installation depth70 mm
Terminal tightening torque, max.75 °C
Terminal tightening torque, min.-40 °C
Combined terminal, topYes
Combined terminal, bottomYes
Fastening methodQuick assembly system
SealableYes
5SY8303-8 — Environmental
ParameterValue
Halogen-freeYes
Silicone-freeYes
Influence of surrounding temperaturemax. 95% to 55°C, max. 55% to 70°C, max. 35% to 75°C

Product details

At 45 °C the 5SY8303-8 carries the full 3 A. At 50 °C it derates to 2.92 A; at 55 °C to 2.85 A. The enclosure can see -40 °C to 75 °C ambient, but the surrounding temperature influence table shows max 95 % RH at 55 °C, dropping to 35 % RH at 75 °C — relevant if the panel sits near a steam line or washdown zone. IP20 with connected conductors; not rated for wet locations without an outer enclosure.

Panel fit and compliance notes

Combined terminal top and bottom — line and load can enter from either side. Touch protection is built in. Halogen-free and silicon-free construction, so it meets clean-room or sensitive-environment specs. Vibration resistance per IEC 60068-2-6: ±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz. The quick-assembly fastening method means it clips onto DIN rail without tools and can be removed with a screwdriver lever.

Frequently asked questions

Where can I buy 5SY8303-8 and how do I get a price?

The 5SY8303-8 is sourced to order against an RFQ through independent distribution. Submit a request for quote (RFQ) for current pricing and availability — confirmed at quote time.

What is 5SY8303-8's listed depth and width?

The 5SY8303-8 has a depth of 76 mm (installation depth 70 mm) and a width of 54 mm (3 modular width units).

Will 5SY8303-8 drop into a panel specified around 5SY4140-7 without rewiring?

Both are 3-pole SENTRON MCBs on the same DIN-rail footprint (3 modular width units), so the mechanical fit is identical. However, the 5SY8303-8 is a D-curve at 3 A, while the 5SY4140-7 is a different rating/curve — verify the branch circuit's load and coordination requirements before swapping. No wiring change needed if the terminals accept the same conductor size.

What compliance documentation does Siemens provide for 5SY8303-8?

The 5SY8303-8 carries ratings per IEC 60947-2 (50 kA breaking capacity), UL 1077 and CSA C22.2 No. 235 (5 kA), and IEC 60068-2-6 vibration. The SENTRON series generally provides CE, UKCA, and EAC declarations; RoHS and REACH compliance is standard for current-production Siemens industrial controls. Specific certificates are available on request.

MPN
5SY8303-8