On the basis of the Fusing Factor, LV fuses are generally classified into 4 types:
- Class P Fuses: These are fuses that have a fusing factor of 1.25 or less and are intended to protect circuits with small overloads
- Class Q1 Fuses: These are fuses having a fusing factor between 1.25 and 1.5
- Class Q2 Fuses: These are fuses having fusing factors between 1.5 and 1.75
- Class R fuses: These are fuses having a fusing factor between 1.75 and 2.5. These are used to protect a circuit against large over-currents only. (Mainly is backup protection)
![](https://i0.wp.com/www.electricalengineering.xyz/wp-content/uploads/2023/01/fusingf.png?resize=825%2C457&ssl=1)