Solar Engineering: When Do Breakers Actually Trip

In solar engineering, ensuring the safety and reliability of the electrical system is crucial. This involves adhering to breaker sizing standards and proper sizing of conductors. UL (Underwriters Laboratories) sets standards for electrical products and systems, including circuit breakers, to ensure their safety and reliability.

Contrary to popular belief, breakers do not trip at any current above their rating instantaneously. If a breaker tripped at its rated current, it would cause frequent nuisance tripping. UL standards require circuit breakers to trip within two minutes when exposed to a current that is 200% of their rated current. Additionally, circuit breakers must trip within one hour when subjected to a current that is 135% of their rated current.

Conductors are wires that carry electrical current between components in a circuit, such as between solar panels, inverters, and batteries. Proper sizing of conductors is closely related to the sizing of circuit breakers. If a breaker doesn’t trip instantaneously at its rated current, it becomes crucial to size conductors correctly to avoid hazards such as overheating, voltage drop, and other potential issues.

Proper sizing of conductors is essential to ensure the safety and reliability of solar power systems. Incorrect sizing can cause overheating and create hazards such as fires or shocks. Undersized conductors can also create excessive resistance, leading to overheating and potential damage.

Conductors should be sized based on the maximum current they are expected to carry, the length of the conductor, the temperature rating, and other factors. By selecting the appropriate conductor size and corresponding breaker size, potential hazards can be avoided, and solar power systems can operate efficiently and safely.

In summary, maintaining the safety and reliability of a solar power system requires adherence to breaker sizing standards and proper sizing of conductors. Circuit breakers must trip at the appropriate current level to avoid nuisance tripping. Conductors must be sized correctly to avoid hazards such as overheating and voltage drop. Proper sizing of conductors and breakers is crucial to ensure that solar power systems operate efficiently and safely.

If you want to know more about solar engineering, check out this post on interconnections: Solar Interconnection Guide.