In response to the significant voltage fluctuations in rural Africa, the most crucial aspect of selecting a miniature circuit breaker (MCB) for lighting electrical Ready Board Box is to ensure that its rated insulation voltage (Ui) is not lower than 600V, in order to guarantee the insulation safety of the equipment itself under the most extreme voltage surges.
Why is the rated insulation voltage (Ui) not less than 600V?
This is because the safety standards commonly adopted for conventional miniature circuit breakers provide ample safety margins for voltage spikes in the circuit. For instance, in Madagascar, where the power grid is severely aged, the voltage may plummet to 160V; or in scenarios powered by unstable generators, the voltage may soar to 456V. The insulation capability of 600V effectively copes with these instantaneous high voltages that far exceed normal values.
And we cannot only focus on the working voltage (Ue)
    Although many circuit breakers are rated with a nominal working voltage (Ue) of 230V/400V, this usually only represents their normal operating voltage range. For instance, a wide operating voltage design of merely "170V-280V" cannot cope with extremely high voltage surges. Therefore, the Ui value, which specifically assesses insulation strength, is fundamental.
As for other key parameters and selection recommendations
Rated operating voltage (Ue): It is recommended to select 230V for single-phase circuits and 400V for three-phase circuits.
Rated impulse withstand voltage (Uimp): It is recommended to be no less than 4kV to withstand transient high voltages such as lightning strikes.
Breaking capacity (Icn/Ics): It is recommended to be no less than 6kA. Rural power grids are prone to short circuits due to aging, necessitating circuit breakers that can safely and reliably interrupt fault currents.
Tripping characteristics: For lighting circuits, it is recommended to use Type C circuit breakers (suitable for general resistive and inductive loads).
To ensure that the selection meets local safety standards, it is recommended to prioritize products that comply with the IEC/EN 60898 international standard.