In the configuration of lighting electrical Ready Board Box in rural Africa, the rated current matching between circuit breakers (usually small circuit breakers MCB) and back-end switches (such as lighting switches and load switches) should follow the principle of "circuit breaker protection wires and back-end components". The specific matching logic is as follows:
Core matching principle: The rated current of the circuit breaker is ≥ the calculated current of the circuit, but ≤ the current carrying capacity of the wire
The core function of a circuit breaker is to trip and protect the circuit when overloaded or short circuited. Therefore, the rated current (In) of the circuit breaker must be less than or equal to the safe current carrying capacity (Iz) of the circuit conductor, while being greater than the actual operating current (Ie) of the circuit.
Formula reference: Ie ≤ In ≤ Iz
Matching with backend switches (such as wall switches)
The rated current of the back-end ordinary lighting switch (usually a toggle switch) is usually 10A or 16A. When designing, the rated current of the upper circuit breaker should be equal to or slightly less than the rated current of the switch to ensure that the switch itself can be protected in extreme situations.
Conventional configuration: For LED lighting fixtures, the circuit current is very small. Usually, 10A or 16A miniature circuit breakers are used in conjunction with 10A switches.
Special case: If the back-end switch controls high-power lamps (such as multiple lamps in parallel), the circuit breaker should use a C-type curve (C16 or C20), and the rated current of the back-end switch should be greater than the rated current of the circuit breaker (such as 16A or 20A for the switch) to prevent excessive temperature rise of the switch contacts.
Special considerations for rural Africa
Considering the large voltage fluctuations and high environmental dust in the local power grid:
Reduced use: In high temperature or dusty environments, circuit breakers are prone to overheating. It is recommended that the actual load current does not exceed 80% of the rated value of the circuit breaker.
Avoid bypassing the level: It is strictly prohibited to use large capacity circuit breakers (such as 32A) to protect small capacity switches (such as 10A), otherwise the circuit breaker may not trip after the switch burns out, causing a fire.
Summary suggestion: Rural lighting circuits usually choose 16A miniature circuit breakers, combined with 10A/16A wall switches, with wire cross-sections not less than 1.5mm ². If it is only for low-power LED lighting, a 10A circuit breaker can be used to provide more sensitive protection.