3A228Switching devices, as follows:

a. Cold-cathode tubes, whether gas filled or not, operating similarly to a spark gap, having all of the following characteristics:
1. Containing three or more electrodes;
2. Anode peak voltage rating of 2,5 kV or more;
3. Anode peak current rating of 100 A or more; and
4. Anode delay time of 10 μs or less;
Note:
3A228.a. includes gas krytron tubes and vacuum sprytron tubes.
b. Triggered spark-gaps having both of the following characteristics:
1. An anode delay time of 15 μs or less; and
2. Rated for a peak current of 500 A or more;
c. Modules or assemblies with a fast switching function, other than those specified in 3A001.g. or 3A001.h., having all of the following characteristics:
1. Anode peak voltage rating greater than 2 kV;
2. Anode peak current rating of 500 A or more; and
3. Turn-on time of 1 μs or less.