Safety Certified Capacitors are rated according to their impulse capability. Impulses are usually identified by T1/T2 impulses where T1=rise time and T2=time to half value, for example 1.2/50µs impulse. More specifically, T1 is the time it takes the pulse to go from 10% to 90% of the peak voltage and T2 is the time it takes the voltage to go from 50% of peak voltage back to that same level. Different applications requiring 10/700µs impulse for telecom applications per IEC 60950 and UL 60950 as well as 1.2/50µs impulse per IEC 60384-14 for AC line applications.