From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Test results for peak voltage discharge across different gap sizes.
| Identifier | ExFiles\Box 142\3\ scan0329 | |
| Date | 1st September 1937 | |
| 2. Rm{William Robotham - Chief Engineer}/RC.{R. Childs}1/MH.{M. Huckerby}1.9.37. TEST NO. | GAP IN INCHES. | PEAK VOLTS FOR DISCHARGE. ------------------------------------------------------ 1. | .570 | 13,760 2. | .585 | 14,150 3. | .608 | 14,590 4. | .625 | 14,940 5. | .643 | 15,200 It is considered that 15,000 volts is the maximum likely to be reached, in conjuction with plugs having .030" gaps, wearing to .035". Therefore, it will be seen that the clearances must be such, that the shortest distance between any electrode, and the nearest earth point, must not be less than .643 inches. Rm{William Robotham - Chief Engineer}/RC.{R. Childs} | ||