Which fuse is bigger AC or DC?

In general, DC (Direct Current) fuses are typically smaller in size compared to AC (Alternating Current) fuses for the same voltage and current ratings. This size difference is due to differences in the way AC and DC circuits behave and the nature of the faults they may encounter.

AC circuits experience zero-crossing points in their waveform where the current drops to zero, allowing for easier interruption of the arc during a fault. This characteristic of AC allows for smaller and more efficient fuses to be designed.

On the other hand, DC circuits have a continuous flow of current without zero-crossing points. When a fault occurs in a DC circuit, the arc produced tends to be more persistent and harder to extinguish compared to AC faults. Consequently, DC fuses need to be designed with more robust arc-quenching capabilities, often requiring larger physical sizes to handle the potential arc energy.

So, while the specific size differences between AC and DC fuses may vary based on the application, voltage, and current ratings, in general, DC fuses tend to be larger than their AC counterparts for equivalent voltage and current specifications due to the differences in fault characteristics between DC and AC circuits.