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).
Supply issues and wiring configuration for a twelve-volt lighting system.
| Identifier | ExFiles\Box 168b\2\ img039 | |
| Date | 26th July 1920 | |
| X 802 To C. from R.{Sir Henry Royce} R1/G26.7.20. Copy to CJ. " " PN.{Mr Northey} " " Hs.{Lord Ernest Hives - Chair} " " Da.{Bernard Day - Chassis Design} X.802. " " EFC. X.2778. RE TWELVE VOLT LIGHTING SYSTEM. X.1369. X.3659. X.1357. There is doubt about whether supplies of lamp holders and bulbs can be easily obtained for 12 volts single wiring system, that is, the lamps have a single contact on the lamp cap, and the lamp holder had a single plunger in the centre of the holder. If these are difficult to get we are obliged to continue to use as standard a double wiring system for the lighting as well as the starter, but as our present standard battery ignition system must be earthed, it is far simpler to use single wiring with an earth return for the lamp circuits and for the starter control. We were arranging in our schemes to insulate the heavy current only belonging to the starter circuit. This enables us to use a comparatively light connection to earth with a small sized fuse protecting it, making the whole equipment less risky from fire by an earth fault on the positive side. R.{Sir Henry Royce} | ||