Key words Electrical breakdown time delay, breakdown voltage, afterglow period, neutral active states.On the basis of the mean value of electrical breakdown time delay t d and the standard deviation of electrical breakdown time delay σ dependence on the afterglow period τ , the mechanisms which dominantly influence to breakdown initiation in nitrogen were separated. It was shown that the positive ions formed in mutual collision of long-lived metastable molecules have a dominant role in breakdown initiation for τ values up to 70 ms. The metastable molecules were derived from previous breakdown and discharge. In this case σ t d and the total time delay t d is approximately equal to formative time t f which decreases in value with the increase of overvoltage. When positive ions have a dominant role in the breakdown initiation the Gaussian distribution describes data of t d ≈ t f very well. For τ > 1 s, N ( 4 S) atoms formed in previous breakdown and discharge, have a dominant role in the breakdown initiation. Then, σ ≈ t d and Laue's distribution, which is valid for statistical time delay ts, describes t d data very well.