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Siemens 5SY8340-8 — 3-Pole MCB (DIN Rail)

Siemens 5SY8340-8 SENTRON MCB, 40 A, 3P, D Curve, 25 kA

MPN5SY8340-8
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Siemens SENTRON 5SY8340-8, 3-pole miniature circuit breaker, 40 A rated current, D tripping characteristic, 25 kA breaking capacity per IEC 60947-2.

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

Specifications

5SY8340-8 — Identification
ParameterValue
Brand nameSENTRON
Number of poles3
Pole configuration3P
Suitability for operationMechanical engineering / industry
5SY8340-8 — Protection
ParameterValue
Tripping characteristic (curve)D
Breaking capacity per IEC 60947-225 kA
Overvoltage categoryIII
IP protection classIP20, with connected conductors
Pollution degree3
5SY8340-8 — Electrical
ParameterValue
Rated current (AC)40 A
Rated voltage (AC, multi-phase)440 V
5SY8340-8 — 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
5SY8340-8 — 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

On DC circuits the same standard gives it 15 kA. For UL 489 / CSA C22.2 No. 235 installations the interrupting rating is 5 kA — enough for most North American branch circuits but check your available fault current. Terminal design is combined top and bottom — line and load can enter from either side, which simplifies busbar routing in a crowded enclosure.

Thermal management and environment

Rated 40 A at 45 °C ambient; at 50 °C it derates to 38.76 A, and at 55 °C to 37.48 A. The surrounding temperature influence curve is published: max 95 % RH up to 55 °C, dropping to 55 % at 70 °C and 35 % at the 75 °C maximum. That matters when the breaker sits next to a contactor bank or drive that raises cabinet internal temperature. IP20 with connected conductors — standard for a DIN-rail MCB; no washdown rating, so keep it inside the enclosure. Halogen-free and silicon-free construction, sealable with a lead seal. Vibration resistance per IEC 60068-2-6: ±1 mm at 5-25 Hz, 50 m/s² at 25-150 Hz.

Frequently asked questions

What are the key ratings for the 5SY8340-8?

40 A rated current, D tripping characteristic, 3-pole. Breaking capacity: 25 kA at 440 V AC per IEC 60947-2, 15 kA DC per IEC 60947-2, and 5 kA per UL 1077 / CSA C22.2 No. 235.

Where can I buy the 5SY8340-8?

Sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time.

What compliance documentation does Siemens provide for the 5SY8340-8?

The breaker carries IEC 60947-2 and UL 1077 / CSA C22.2 No. 235 certifications. RoHS and REACH declarations are standard from Siemens for this SENTRON series.

MPN
5SY8340-8