When a fuse is applied in an ambient temperature exceeding the standard 25°C, the fuse current rating should be derated. This means that a higher current rated fuse may be needed at higher temperatures. Conversely, operating at an ambient temperature lower than the 23°C standard allows the use of a lower fuse amp rating. The lowest suitable fuse rating is obtained by rounding up the calculated value to the next higher amp rating shown in the fuse datasheet. Ex. a 1A fuse working at room temp, must be temp derated to 1.25A at 125°C, or to 0.8A at -55°C to produce the same performance.