| 1/00 | Details of spark gaps |
| 1/02 | Details of spark gaps Means for extinguishing arc |
| 1/04 | Details of spark gaps Means for extinguishing arc using magnetic blow-out |
| 1/06 | Details of spark gaps Means for extinguishing arc using magnetic blow-out with permanent magnet |
| 1/08 | Details of spark gaps Means for extinguishing arc using flow of arc-extinguishing fluid |
| 1/10 | Details of spark gaps Means for extinguishing arc using flow of arc-extinguishing fluid with extinguishing fluid evolved from solid material by heat of arc |
| 1/12 | Details of spark gaps Means structurally associated with spark gap for recording operation thereof |
| 1/14 | Details of spark gaps Means structurally associated with spark gap for protecting it against overload or for disconnecting it in case of failure (H01T 1/15, H01T 1/16, H01T 1/18 take precedence) |
| 1/15 | Details of spark gaps for protection against excessive pressure |
| 1/16 | Details of spark gaps Series resistor structurally associated with spark gap |
| 1/18 | Details of spark gaps Electrolytic device structurally associated with spark gap |
| 1/20 | Details of spark gaps Means for starting arc or facilitating ignition of spark gap |
| 1/22 | Details of spark gaps Means for starting arc or facilitating ignition of spark gap by the shape or the composition of the electrodes |
| 1/24 | Details of spark gaps Selection of materials for electrodes (H01T 1/22 takes precedence) |
| 2/00 | Spark gaps comprising auxiliary triggering means (triggering circuits H01T 15/00) |
| 2/02 | Spark gaps comprising auxiliary triggering means (triggering circuits H01T 15/00) comprising a trigger electrode or an auxiliary spark gap |
| 4/00 | Overvoltage arresters using spark gaps (H01T 2/00 takes precedence; overvoltage protection circuits using spark gaps H02H 9/06) |
| 4/02 | Overvoltage arresters using spark gaps (H01T 2/00 takes precedence; overvoltage protection circuits using spark gaps H02H 9/06) Details (of spark gaps H01T 1/00) |
| 4/04 | Overvoltage arresters using spark gaps (H01T 2/00 takes precedence; overvoltage protection circuits using spark gaps H02H 9/06) Housings (H01T 4/06 takes precedence) |
| 4/06 | Overvoltage arresters using spark gaps (H01T 2/00 takes precedence; overvoltage protection circuits using spark gaps H02H 9/06) Mounting arrangements for a plurality of overvoltage arresters |