Lightning conductors
G.E. Venning Thomas, an electrical engineer (A.M. Inst. E.E.) active in the Straits Settlements, published these practical notes in 1905 to correct what he regarded as widespread misapplication of lightning protection principles on government and municipal buildings in the colony. His central argument is that the prevailing practice of installing massive copper rods and elaborate multi-branched terminals—rooted in an obsolete “law” linking a conductor’s protective area to its height—is both wasteful and inferior to a network system of light galvanised iron wire with numerous small interconnected points.
Summary
Thomas writes from direct experience inspecting conductors on Government and Municipal buildings across the Straits Settlements, and his tone is that of a practitioner correcting administrative habits rather than a theorist. He identifies two persistent errors: first, the continued reliance on the discredited notion that a single tall conductor “protects” a defined radius, and second, an obsessive focus on earth resistance measurements that distracts from the more important design of the above-ground system. His proposed alternative is a roof network of many short points (one per fifteen to twenty feet of ridge, plus every corner) interconnected with light stranded galvanised iron wire, bringing the system as close as feasible to the continuous metallic screen that modern electrical theory held to be the ideal safeguard.
The article is structured as a sequence of practical recommendations rather than a formal treatise. Thomas addresses material selection, point design (including a novel tubular point that eliminates soldered joints on the roof), the use of rainwater downpipes as down-conductors, and the proper siting of earth connections. He draws on local incidents—including a discharge at the Civil Prisons in Singapore that blew a three-foot hole in the ground above a poorly sited earth—to demonstrate that imperfect earth connections are far less dangerous than commonly feared, provided they are placed well away from foundations. The powder magazine example serves as his principal illustration of institutional waste: a broad copper strip system with eight earth connections, of which seven were entirely unnecessary, could have been replaced at lower cost by a lighter, more effective network.
Key Findings
- The powder magazine in the Colony used broad strip of pure copper with eight earth connections; Thomas judged seven of these unnecessary and argued that an equivalent weight of copper in light stranded wire would have provided superior protection (p. 218).
- Thomas’s recommended material is galvanised iron cable of seven strands, No. 16 gauge (7/18), secured with zinc saddles, which he describes as pliable, mechanically strong, and unobtrusive (p. 218).
- For the same outlay, stranded galvanised wire covers not less than twenty-five times the surface area of a single one-inch copper rod; factoring in labour and accessories, Thomas claims twenty times better protection (p. 221).
- At the Civil Prisons, Singapore, a lightning discharge through the conductor blew out the soil over the earth connection, leaving a hole approximately three feet in diameter and two feet deep; the earth had been a coiled cable end buried only a couple of feet on a slope (p. 220).
- Thomas recommends the earth connection be taken at least one hundred feet from the building in a trench twelve to fifteen inches deep, reaching permanently damp soil (p. 221).
- For extensive buildings he made a practice of bringing down six or more down-conductors, joined in a continuous trench round the building before continuing to the deep earth (p. 221).
Conclusion
Thomas’s definitive takeaway is that the economics of lightning protection in the Straits Settlements were being mismanaged: authorities were spending heavily on visually impressive but technically inferior single-conductor systems when a modestly designed network of light galvanised wire would deliver substantially greater protection for the same or lower cost. His notes function as a corrective memorandum to colonial engineering practice, grounded in the modern electrical understanding that a continuous metallic screen—not a single tall rod—constitutes the true safeguard.
Context
- Thomas was an electrical engineer (A.M. Inst. E.E.) conducting inspections of Government and Municipal buildings in the Straits Settlements; the article is dated Penang, September 1904, and reflects his professional role in advising colonial authorities on building safety.
- The piece represents applied electrical engineering knowledge being disseminated through a learned society journal to reach a colonial administrative readership, and its recommendations were evidently intended to influence future government procurement and construction standards in the Straits Settlements.