Differential Blocks
A differential block is a crucial component of any electrical installation. Installed in the electrical panel, it…
Understanding the Role of a Differential Block
Differential blocks continuously monitor current balance. As soon as an insulation fault occurs, they disconnect the power supply within milliseconds.
When someone accidentally touches a live conductor, some current flows to earth. This leakage creates an imbalance that the device detects immediately. The differential block trips before the current becomes dangerous to humans.
The device's sensitivity determines the trip threshold. A 30mA sensitivity provides effective protection for people, corresponding to the physiological danger threshold established by medical studies. Higher sensitivities (300mA, 500mA) are primarily used for fire protection.
The disconnection time never exceeds 300 milliseconds for a standard fault current. This rapid response significantly reduces the risk of serious electric shock. Selective models follow a delayed tripping curve to prioritize the operation of downstream protection devices.
Differential blocks are installed directly on DIN rails in electrical panels and connected in series with circuit breakers. This configuration ensures optimal protection for each electrical circuit.
Types of Differential Blocks Available
AC Type Differential Block
The AC type is ideal for standard lighting and socket circuits. These models are commonly used in most domestic installations in the UK.
Our Legrand DX³ AC type differential blocks cover ratings from 25A to 125A. A two-pole (2P) configuration protects single-phase 230V circuits, while a four-pole (4P) differential block protects three-phase 400V installations.
The Schneider Electric Vigi iC60 range also offers high-performance AC solutions. These products are perfectly compatible with the iC60 series circuit breakers. Their compact size optimizes space in electrical panels.
Type A Differential Block
Type A is required for circuits supplying modern electronic equipment such as induction hobs, washing machines, and computers.
Regulations now mandate the installation of Type A devices for certain applications. Specialized circuits of 20A and above must be protected by this type of device. This requirement stems from technological advances in domestic appliances.
One-Elec stocks Type A differential blocks from the Legrand DX³ and Schneider Electric Acti9 series. These models cover all configurations: 2P, 3P, and 4P, with ratings ranging from 25A to 125A depending on requirements.
Super Immunized (SI) models resist nuisance tripping by filtering transient disturbances without compromising safety. This technology significantly improves electrical installation availability.
Type B Differential Block
Type B detects all types of fault currents, including smooth direct currents. It is essential for installations with variable frequency drives. Photovoltaic systems and EV charging stations also require this protection.
These devices are more expensive than Types AC and A and are only required for specific applications. A risk analysis determines whether this level of protection is necessary.
Criteria for Choosing a Differential Block
The nominal current rating must match the maximum current of the protected circuit and must never exceed the circuit breaker's rating. This rule ensures proper coordination between protective devices.
Sensitivity is chosen according to the application and regulations. Final circuits require 30mA sensitivity, while main differential blocks may use 300mA or 500mA sensitivity.
The number of poles depends on the installation type. Single-phase circuits use two-pole (2P) units, while three-phase installations require four-pole (4P) versions. Certain three-pole (3P) configurations exist for special applications.
The nominal voltage must match the installation voltage. 230V models are used for single-phase circuits, while 400V versions suit three-phase installations. Always verify this specification before purchasing.
The number of modules influences electrical panel selection. Differential blocks typically occupy 2 to 4 modules depending on their configuration. Consider this when designing the panel layout.
The selective function delays tripping to prioritize downstream protection devices, improving service continuity by limiting power outages. This feature is particularly useful in commercial installations.
Reputable Brands to Consider
Legrand is a market leader in France with its DX³ range. These differential blocks are renowned for their reliability, and their compatibility with the entire modular range ensures easy installation.
The Legrand products in our catalog include all standard types and ratings, with each product complying with NF and CE standards.
Schneider Electric also offers high-quality differential blocks with its Acti9 and NG125 ranges. The Vigi modules integrate seamlessly with iC60 and iDT40 circuit breakers. This modular approach simplifies maintenance and upgrades.
Schneider Electric's Super Immunized (SI) technology (ref. A9Y64740 or ref. A9Y64625) dramatically reduces nuisance tripping.
We guarantee delivery within 24-48 hours in mainland France for all stocked products. Vigi, Acti, DX³... unsure which equipment to choose? Our technical team will advise you on the right differential block at the right price. Whether you're a professional or private individual, don't hesitate to contact us to benefit from our expertise in differential block protection!