Question: what is the difference between class j and class t fuses?
Answer: What is the difference between UL Class RK1 and RK5 fuses? Class RK1 and RK5 fuses are the same physical size but Class RK1 fuses are more current-limiting than Class RK5 fuses. RK1 fuses can provide better protection because they allow less damaging energy to pass through them while opening (blowing).