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).
The 4-EX vehicle's distribution board, discussing earthed versus double wiring systems.
| Identifier | ExFiles\Box 50\1\ Scan147 | |
| Date | 17th June 1921 | |
| X4410 Extract from R1/G17.6.21. X.3764 - REPORT ON 4-EX JUST RETURNED FROM AMERICA. DISTRIBUTION BOARD. X.3976 X.4173 X.2515 X.4172. Regarding the distribution board, we assume that you will get one of these made by Bijur or another firm of good quality and of the arrangement of the R.R. design. You will notice with this system of wiring that there is only one earth which is made on this distribution board through a small gauge copper fuse. This naturally is necessary to make the battery ignition circuit complete, but is not required for any other purpose, and therefore for safety can have a fuse that will only carry a few amperes. It is regretful that the double wiring system naturally requires more wires and more complication than an earthed system, but it has the advantage of being very much safer in the case of accidentel contacts, and safer from a fire point of view when the car is stored in the garage. You will therefore see that we think it is worth while having our earthed arrangement unless we go in for an entirely earthed system with lamps having central contacts. We shall be glad of your views as to the future policy, whether such an earthed system be adopted, or whether you might prefer the double wiring system that is now proposed. It has [strikethrough]low tension battery system[/strikethrough] occurred to us that it may be worth while to entirely insulate the low tension battery system also, and therefore do away with all earth connections. In the arrangement of distribution board which we have produced, testing is somewhat simpler than is usual. Anyone with moderate electrical education can fairly easily trace the wires in case of a fault. | ||