Circuit Breakers

What is the role of an electrical circuit breaker?

Magnetic-thermal circuit breakers play an essential role in protecting electrical installations and user safety. They protect both the equipment to which they are connected and all of the installation's electrical circuits and cables.

A lack of adequate protection can have serious consequences: risk of fire caused by cables overheating during an overload, irreversible damage to connected electrical appliances during a short circuit, or worse still, electrocution of a person in the event of a fault in the insulation. The circuit breaker, which automatically cuts off the power supply as soon as a fault is detected, is therefore an essential safety barrier in any compliant installation.

Why is the trip curve of a circuit breaker important?

Because each electrical circuit is capable of withstanding a defined current and, if this is exceeded, the circuit breaker must trip to avoid damage to the installation and electrical equipment. It is therefore the value of the current that the protective device can withstand for a given period of time.

The circuit breaker's trip curve sets the trip threshold for the circuit breaker and varies depending on the equipment to be powered. It is therefore an indicator that should not be overlooked when purchasing a circuit breaker. The NF EN 60898 standard defines five trip curves:

• Curve B: trip threshold between 3 and 5 ln. This curve is mainly used for electrical circuits with long cable lengths.
• Curve C: trip threshold between 5 and 10 In. This is the most commonly used curve for protecting domestic installations.
• Curves D and K: trip threshold between 10 and 14 In. Mainly used to protect circuits and cables with very high current peaks when power is switched on, such as motors, heat pumps and CMVs.
• Curve Z: trip threshold between 2.4 and 3.6 In. For the protection of electronic circuits and variable speed drives.

What are the three types of circuit breakers?

There are three main types of circuit breakers on the market, all available from One-Elec:

• The connection circuit breaker, also known as a subscriber circuit breaker or main circuit breaker. This is the starting point of the electrical circuit, which separates the private installation from the public grid.
• Branch circuit breakers are the most common type of circuit breaker in electrical panels, as they protect each electrical circuit.
• Residual current circuit breakers are placed upstream of branch circuit breakers and are primarily designed to protect people from the risk of electric shock due to leakage current.

Schneider Electric, Legrand, Hager and ABB thermal magnetic circuit breakers are available from One-Elec

Schneider Electric, Legrand, Hager and ABB thermal magnetic circuit breakers are available from One-Elec. We offer models for all types of installations, in single, double, triple or quadruple pole versions with different trip curves (B, C, D, K, Z), for a rated current of 2 to 3200 A. Our products are perfectly suited for the residential, tertiary and industrial sectors. Each circuit breaker is a key component of your electrical installation, ensuring optimal protection against overloads and short circuits.

Why are they called thermal magnetic circuit breakers?

Thermal magnetic circuit breakers use two technologies to provide protection:

• Magnetic technology protects against short circuits. The circuit breaker, equipped with an electromagnetic coil, reacts instantly (20 ms) to a very sudden increase in current (Icc > 3 to 10 In). It converts this increase into mechanical energy and causes the circuit to open and the circuit breaker to trip.
• • Thermal technology protects against electrical overloads. The circuit breaker, equipped with a bimetal strip, deforms under the effect of heat induced by a low overcurrent (1.2 to 5 In) over a relatively long period of time, between 30 seconds and 10 minutes. It converts the increase in current into mechanical movement, in this case opening the circuit and thus tripping the circuit breaker.

Schneider Electric circuit breakers: Resi9 and Acti9 circuit breakers

One-Elec offers you the most recognised ranges of Schneider Electric circuit breakers on the professional electrical market.

For demanding installations requiring up to 125 A, the Schneider Electric Acti9 range offers high-performance modular circuit breakers in single, double, triple or quadruple pole versions, compliant with current electrical standards and suitable for commercial and industrial environments. Their mounting on DIN rails and their compatibility with electrical distribution systems make Schneider Electric circuit breakers a quality choice for effectively securing your electrical installation.

We also sell a few items from the Resi9 range, which is specially designed for the residential sector. This range offers reliable protection up to 63 A with plug-in options for easy installation in your electrical panel. These neutral phase circuit breakers are available in different ratings and trip curves to precisely meet your circuit protection needs.

Legrand circuit breakers on One-Elec: DX³ and DNX³ ranges

Looking for a Legrand circuit breaker? Our catalogue offers products from the DX³ and DNX³ ranges, renowned for their reliability and compliance with current electrical standards. The DX³ range is robust and offers four-pole circuit breakers available in different trip curves, compatible with traditional HX³ combs and ideal for overcurrent protection in demanding installations.

The DNX³ range from Legrand is more compact with its smaller modules and is ideal for residential installations with phase+neutral circuit breakers that provide effective protection against overloads and short circuits. These Legrand residual current circuit breakers offer optimum safety thanks to their adapted breaking capacity and latest-generation magneto-thermal technology. Please do not hesitate to contact our technical team for assistance in selecting the Legrand circuit breaker that best suits your electrical protection needs.

One-Elec's range of tertiary and industrial circuit breakers

One-Elec offers a comprehensive range of medium and high power circuit breakers for currents above 125 A and up to 3200 A. This range meets the specific needs of demanding tertiary and industrial installations. Our power circuit breakers, available in moulded or open enclosures, offer features suitable for critical applications: adjustable electronic trip units, high breaking capacity and communication options for remote monitoring.

Ideal for protecting transformers, generators, high-power motor starters or low-voltage main switchboards (LVMS), these compact circuit breakers combine exceptional performance in a small footprint to optimise space in your electrical cabinets. A low-voltage solution for compact circuit breakers with ultra-concentrated performance.

Switches and other related products

In addition to circuit breakers, we offer switches, modular modules, poles, terminals, residual current devices and other components from leading brands such as Schneider, Legrand and ABB to complete your electrical installation and ensure optimal safety. Type A or AC residual current devices effectively complement your electrical panel for enhanced protection against insulation faults. Browse our online catalogue to discover all our products available in stock, with solutions tailored to all types of electrical installations, whether residential, commercial or industrial.

Choose safety with circuit breakers stocked at One-Elec

Need advice on a product? Contact our technician, who will give you all the details about our stock items from Legrand, Schneider, and more! Sign up for our newsletter to stay up to date on our promotions and take advantage of our products at the best prices. Delivery within 24/48 hours in mainland France for all products in stock.