The specification of the porcelain insulator as follows :
| Type | 55-1 | 55-2 | 55-3 | 55-4 | 55-5 |
| Creepage distance mm | 102 | 127 | 178 | 229 | 305 |
| Dry arcing distance mm | 57 | 86 | 114 | 127 | 159 |
| Cantilever strength Kn | 13 | 11 | 11 | 13 | 13 |
| Low frequency dry flashover voltage | 35 | 45 | 56 | 65 | 80 |
| Low frequency wet flashover voltage | 20 | 25 | 30 | 35 | 45 |
| Critical impulse flashover pos kv | 50 | 70 | 90 | 105 | 130 |
| Critical impulse flashover Neg kv | 70 | 85 | 110 | 130 | 150 |
| Power-freqency puncture voltage kv | 50 | 70 | 90 | 95 | 115 |
| Test voltage to ground kv | 5 | 5 | 10 | 10 | 15 |
| Net weight eash pprox KG | 0.5 | 0.65 | 1 | 1.55 | 2.75 |
| Number in standard package | 60 | 40 | 30 | 16 | 12 |
