The ac power input.
Where other externally exposed lines interface with the equipment.
Rectifier outputs of 5 to 48 V dc power supplies that operate from commercial ac power and supply
operating power for solid-state equipment.
220.127.116.11.2 Transient Definition. The waveform and amplitude of transients that may appear on commercial ac
input lines and other landlines connected to equipment are provided in this paragraph.
AC powerline transients. The number and amplitude of lightning generated transients projected to
occur on ac power inputs to equipment over a 10-year period are listed in Tables 1-17 and 1-18. The waveform
for the transients is 8-by-40 microseconds where 8 microseconds is the risetime from zero to peak amplitude,
and 40 microseconds is the time from the start of the transient until exponential decay to 50% of peak value.
The transients listed are based on the data in Section 18.104.22.168. The transients listed in the two tables represent
clamp voltages that will appear across equipment by the facility secondary ac arrester installed at the main
service disconnect means (see Section 22.214.171.124) when discharging transient surges. Voltages and currents
actually appearing across protected equipment will necessarily be related to the amounts and type of equipment
operating from power supplied by the main service disconnect means.
Table 1-17. Transient Surges, Line-to-Ground, Expected to
Appear Across Equipment by Secondary AC
Surge Suppressor Over a 10-Year Period
Surge Current Amplitude
Number of Surges
1.5 kV, 100 A
2 kV, 200 A
2.5 kV, 300 A
3 kV, 500 A
3.5 kV, 1 kA
4 kV, 1.5 kA
4.5 kV, 2 kA