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).
Letter to the Managing Director discussing the advantages of a single-wire earthed electrical system and a new distribution board.
| Identifier | ExFiles\Box 168b\2\ img057 | |
| Date | 18th August 1921 | |
| R.R.236.1m-T S.H.M.296.19-5-18.1500 X802 CC Mr. Belnap. Mr. Nadin. Oy7-G 18821. August, 18, 1921. Mr. Claude Johnson, Managing Director, Rolls-Royce Ltd., London, England. Attention: Mr. Royce & Works Committee. Dear Sir: X.3976. Re: Parts on 4-EX. X.802. Distribution Board. (Replying R1/C17.6.21) X.3659. A sample of the distribution board made by the Bijur Co. is being shipped at an erly date, which incorporated the scheme of wiring used on 4-EX as originally sent, but uses standard S.A.E. cylindrical glass fuses which are obtainable everywhere. With regard to Mr. Royce's question on the earthed or single wire system, we believe that the advantages of this system far outweigh the disadvantages of increased fire risk. We should list the advantages of the single wire system as - (a) Saving weight and cost of wire, terminals and conduits. (b) Ease of tracing earths. (c) Simplifying lamp connections and making the terminals for the lamp sockets more robust because of having more room. (d) Avoiding the possibility of accidental short circuits when inserting lamps in sockets. With the single wire system, if a fuse is inserted at the commencement of each circuit, there is little danger of fire with the earthed system because any considerable earth will blow the fuse. From the point of view of the American user, the earthed system is satisfactory and is universal on modern American cars. The two-wire system is not recognised by the S.A.E. and though at present supplies of double contact | ||