Not sure what breaking capacity is or how to choose the right breaking capacity for a circuit breaker? The experts at One Elec explain everything in this article.
What is the Breaking Capacity of a Circuit Breaker?
Breaking capacity is the ability of a circuit breaker to interrupt a short circuit. There are several scenarios to consider:
For Residential Properties
The short circuit in residential settings will be limited by the equipment installed by Enedis. It's important to know that circuit breakers installed in homes must pass tests according to the EN 60898 standard, which defines a breaking capacity for unlimited resetting in case of a short circuit.
As a homeowner, you are not trained in electrical risks, and this circuit breaker must maintain its ability to interrupt short circuits even if you reset it while the fault is still present.
In this case, the breaking capacity must be 3000A if you have a limited tariff (formerly known as blue tariff) up to 60A three-phase.
Other Cases (Labor Code and Public Buildings)
Depending on the type of tariff subscribed to, there will be characteristics linked to the tariff, and in this case, we use the test results from the EN 60947 standard. This standard characterizes the ultimate breaking capacity of the circuit breaker - the maximum capacity the circuit breaker can handle without immediate deterioration. This ultimate capacity is limited to a specific number of short-circuit interruptions.
For limited tariffs in this case, the breaking capacity according to EN 60947 is a minimum of 4.5 kA.
Monitored Tariff Cases
The monitored or yellow tariff is a subscription where the transformer is not far away but still belongs to Enedis. The neighborhood transformer generally has a limited capacity (1000kVA), which limits the short-circuit current to approximately 20kA at the cabinet level.
Circuit breakers with a breaking capacity of 20kA are rather large, and installing them on all feeders would result in an oversized cabinet.
Manufacturers have developed optimization solutions called "filiation" or "association." These solutions are specific to each manufacturer and are not interchangeable between brands.
Example of optimization:
- Primary circuit breaker with a breaking capacity of 36kA according to EN60947-2
- Second stage at 10kA or more depending on the caliber and model
- Third stage at 6kA or more depending on the rating and model
This solution is one of many optimization possibilities. Depending on your installation, different optimizations may be possible.
Feel free to contact the One Elec team for sizing of breaking capacities and other elements such as cabinets, busbars, etc.
