wherein the break is in air at atmospheric pressure, e.g. in open air

Full Title

High-tension or heavy-current switches with arc-extinguishing or arc-preventing means > Switches wherein the means for extinguishing or preventing the arc do not include separate means for obtaining or increasing flow of arc-extinguishing fluid > wherein the break is in gas (vacuum switches H01H33/66) > wherein the break is in air at atmospheric pressure, e.g. in open air