Siemens 5SU1356-1KK25 Single-Phase Earth Leakage Breaker RCCB 25A 30mA 1P+N C

The Siemens 5SU1356-1KK25 is a high-performance single-phase earth leakage circuit breaker (RCCB) designed for robust protection in various electrical installations. This device combines residual current and overcurrent protection, ensuring safety against electric shock, fire hazards, and equipment damage. Engineered for reliability, it features a compact design for efficient space utilization in distribution boards. The 5SU1356-1KK25 is characterized by its 25A rated current, 30mA tripping residual current, and a Type C tripping characteristic, making it suitable for applications with moderate inrush currents. Its 1P+N (1 pole + neutral) configuration simplifies wiring and installation.

Product Specifications

| Parameter                        | Value                                      |

| :------------------------------- | :----------------------------------------- |

| Product Type                 | Residual Current Circuit Breaker (RCCB)    |

| Model Number                 | 5SU1356-1KK25                              |

| Brand                        | Siemens                                    |

| Poles                        | 1P+N (1 Pole + Neutral)                    |

| Rated Current (In)           | 25 A                                       |

| Rated Residual Current (IΔn) | 30 mA                                      |

| Tripping Characteristic      | Type C                                     |

| Rated Breaking Capacity (Icn)| 6 kA (according to EN 61009-1)             |

| Rated Voltage (Un)           | 230/240 V AC                               |

| Frequency                    | 50 Hz                                      |

| Protection Class             | IP20 (when installed in distribution board)|

| Overvoltage Category         | III                                        |

| Energy Limiting Class        | 3                                          |

| Mechanical Service Life      | 10,000 switching cycles (typical)          |

| Surge Current Resistance     | 1 kA (at 8/20 µs)                          |

| Conductor Cross-Section      | Solid: 0.75-35 mm², Stranded: 0.75-35 mm²  |

| Housing Feature              | Halogen-free, Silicon-free                 |

Core Features & Market Positioning

The Siemens 5SU1356-1KK25 stands out in the market due to its integration of residual current and overcurrent protection within a single, compact device, offering a cost-effective and space-saving solution for electrical safety. Its SENTRON design ensures high reliability and consistent performance, a hallmark of Siemens' commitment to quality in electrical engineering. The device is positioned as a premium safety component for residential, commercial, and light industrial applications where dependable protection against earth faults and short circuits is paramount. Market feedback often highlights its ease of installation and the robust build quality expected from Siemens.

Key Application Scenarios

This RCCB is ideally suited for protecting circuits in environments where the risk of earth leakage is present, such as installations with increased humidity or where conductive surfaces are common. Typical applications include:

  Residential Buildings: Protecting circuits for lighting, sockets, appliances, and bathrooms.  Commercial Spaces: Ensuring safety in offices, retail stores, and public buildings.  Light Industrial Settings: Safeguarding machinery and control circuits where precise and reliable fault detection is necessary.  Protection Against Direct Contact: The 30mA sensitivity provides essential protection against electric shock for personnel.

Practical System Integration Guidance

Integrating the Siemens 5SU1356-1KK25 into existing electrical systems is straightforward due to its standard modular design, fitting into any standard DIN rail. The device features dual-chamber terminals, simplifying the connection of conductors with different cross-sections. Wiring should follow local electrical codes, with line and neutral connections correctly identified. For proper functioning, the neutral conductor must be connected to the designated terminal. The device can be installed at the beginning of a circuit to protect downstream components. When used in a distribution board, it achieves an IP20 protection class.

Operation and Risk Mitigation

The 5SU1356-1KK25 operates by continuously monitoring the balance of current flowing through the live and neutral conductors. If an imbalance occurs, indicating current flowing to earth (an earth fault), the device rapidly trips, disconnecting the power supply to prevent hazards. This rapid disconnection is crucial for mitigating risks such as electric shock and fire. The C-type tripping characteristic means it can handle moderate inrush currents from inductive loads without nuisance tripping, while still providing sensitive protection against earth leakage faults. Regular testing of the RCCB's functionality using its integrated test button is recommended to ensure ongoing safety.

Scalability & Long-Term Value

As an active product in Siemens' SENTRON range, the 5SU1356-1KK25 benefits from compatibility with a wide array of modular accessories and related protection devices from Siemens. This allows for future expansion or upgrades to the electrical installation's protection strategy. Integration with modern building management systems or industrial control platforms is facilitated by the standardized design and reliable performance. Siemens' commitment to product longevity and continuous innovation ensures that components like the 5SU1356-1KK25 remain relevant and supported for years, offering long-term value and dependable protection for electrical systems.

Frequently Asked Questions

1. What is the primary function of the Siemens 5SU1356-1KK25 RCCB?

This device provides combined protection against residual currents (earth faults) and overcurrents (overloads and short circuits). It is designed to enhance safety in electrical installations.

It ensures protection against dangerous electric shocks, which is vital for personnel safety. The RCCB also safeguards electrical equipment and wiring from damage caused by faults. Its rapid tripping mechanism prevents hazards like fires stemming from persistent earth leakage.

The 30mA residual current sensitivity is ideal for direct contact protection, preventing severe injury from accidental touching of live conductors. This makes it a fundamental safety device in many applications.

2. What does the 'C' in the C-Char tripping characteristic signify?

The 'C' characteristic indicates the device's response to inrush currents. It means the breaker can tolerate higher temporary surges of current without tripping.

This feature is beneficial for circuits supplying inductive loads, such as motors or transformers, which naturally draw more current upon startup. It helps prevent nuisance tripping during normal operation of such equipment.

However, it still provides sensitive protection against earth leakage faults at 30mA, maintaining its core safety function. It balances protection with operational reliability for specific load types.

3. Can the 5SU1356-1KK25 be used for both single-phase and three-phase systems?

The Siemens 5SU1356-1KK25 is specifically designed as a single-phase (1P+N) earth leakage circuit breaker. It is not intended for use in three-phase electrical systems.

For three-phase applications, a different configuration of RCCB or a combination of devices would be required. Always ensure the breaker's pole configuration matches the system it is intended to protect.

Using the correct number of poles is critical for safety and proper operation, preventing incorrect wiring and potential hazards. Consult the product documentation for appropriate system matching.

4. What is the breaking capacity of the Siemens 5SU1356-1KK25?

The rated breaking capacity (Icn) of this RCCB is 6 kA according to EN 61009-1. This indicates the maximum fault current it can safely interrupt.

It also has a breaking capacity of 15 kA according to IEC 60947-2, relevant for certain industrial applications. This high capacity ensures reliable protection even in situations with significant short circuits.

Ensuring the breaking capacity of the protective device is adequate for the circuit's prospective fault current is a fundamental safety requirement in electrical design.

5. How does the 30mA tripping residual current enhance safety?

A 30mA tripping residual current is considered a standard for personal protection against electric shock. This level of sensitivity ensures rapid disconnection of power if a fault occurs.

It significantly reduces the risk of severe injury or fatality from indirect contact, where a person touches a conductive part that has become live due to a fault. It also protects against direct contact with live conductors in certain scenarios.

This sensitivity is vital in areas where the risk of electric shock is higher, such as damp environments or locations accessible to the public. It provides an essential layer of safety for individuals.

6. What conductor cross-section sizes can be connected to the 5SU1356-1KK25?

This RCCB accepts a wide range of conductor sizes for versatile installation. It can accommodate solid conductors from 0.75 mm² up to 35 mm².

For stranded conductors, the same range of 0.75 mm² to 35 mm² is supported. Finely stranded conductors with core end processing can be connected within the range of 0.75 mm² to 25 mm².

The dual-chamber terminals facilitate easy connection of conductors with different cross-sections, simplifying wiring tasks. Always ensure connections are tight and secure for optimal performance.

7. Is the Siemens 5SU1356-1KK25 suitable for all types of residual currents?

The 5SU1356-1KK25 is specifically designed for Type AC residual currents. This means it is effective for detecting sinusoidal alternating currents that may flow to earth.

It is not designed to detect pulsating DC residual currents or smooth DC residual currents. For such applications, RCCBs of Type A, B, or F would be necessary, depending on the specific fault current characteristics.

Using the correct Type of RCCB for the expected fault current is critical for ensuring reliable protection and preventing hazards. Always verify the type of residual current expected in the installation.

8. What is the IP rating of the 5SU1356-1KK25 and what does it mean?

The IP rating of the 5SU1356-1KK25 is IP20 when installed within a distribution board with connected conductors. This rating signifies protection against solid objects larger than 12.5mm (like fingers) and no protection against water.

IP20 indicates that the device itself offers basic protection against accidental contact with live parts, assuming it's properly enclosed within a panel. This is standard for indoor electrical enclosures.

Ensure the distribution board is properly sealed and installed according to manufacturer guidelines to maintain the intended level of protection for the overall installation.

9. How do I reset the 5SU1356-1KK25 after it has tripped?

After a trip, the cause of the fault must be identified and rectified. Once the fault is cleared, the breaker can be reset by moving the operating lever to the 'ON' position.

If the breaker trips again immediately after resetting, it indicates the fault condition persists. Do not repeatedly attempt to reset the breaker without addressing the underlying issue, as this can be dangerous.

If the cause cannot be identified or resolved, consult a qualified electrician to diagnose and repair the circuit or the device itself.

10. What is the typical lifespan of the Siemens 5SU1356-1KK25?

The Siemens 5SU1356-1KK25 has a typical mechanical service life of 10,000 switching cycles. This refers to the number of times the breaker can be operated without mechanical failure.

Electrical life, which depends on the number and magnitude of fault currents interrupted, can be shorter. However, for standard residential and commercial use, these devices are designed for long-term operation.

Regular testing, as indicated by the integrated test button, helps ensure the device remains operational and safe throughout its intended service life.