Electrical Cables and Cable Drums
Modelling the large cable drums used to transport heavy electrical cables is discussed in 'Wagon Loads and Materials Handling - Wagon Loads - Introduction'
Electrical wiring has always favoured copper, this conducts electricity well and is soft and malleable, making it easy to 'draw' into long thin wires and allowing the laid up multi-strand wires to be bent about.
One of the first large scale applications for electrical wiring was the telegraph system, which used single strand copper wires suspended from insulators to carry its signals over great distances (see also 'Appendix One - Postal Services and Telephone Networks'). By the mid 19th century the demand for telegraph wire had provoked considerable development of wire drawing technology and by the 1870s machine-drawn copper wire of great consistency was routinely produced.
Insulating cables proved somewhat problematic, the initial impetus for the development of insulated cable was not so much domestic and industrial supplies but international telegraph networks. In Britain sending a telegram to another British town was known as 'sending a wire' but sending a telegram abroad was known as 'sending a cable', because the line across the sea had to be a fully insulated cable. Some people tried putting the wire in a glass tube or applying a thick coating of varnish, but for flexible insulation coating wires in rubber or gutta percha (a rubbery substance obtained from a Malaysian tree) and oil soaked yarn provided some of the more practical options.
By the later 19th century vulcanised rubber was viable and paper soaked in an insulating oil proved successful for higher powered cables (the paper type insulation was still common in the 1960s and may still be used today). In 1850 they got a working telegraph cable across the channel to France and a few years later a cable was laid between Scotland and Ireland. In 1858 they managed to get a cable working across the Atlantic (the Royal navy had to lend them the ships to lay this with) but this trans-Atlantic cable failed after a few months and it was replaced only in the later 1860s when I. K. Brunel's 'Great Eastern' (at the time the worlds largest ship) was fitted out as a cable layer for the job. Under-sea cables remained the most valuable side to the industry until the later 20th century. By the 1950s the under sea or 'submarine' cables were generally 'co-axial', a central multi-stranded wire conductor covered in an insulating material and with a layer of metalised paper wrapped round it to shield it from electrical interference. This then has a 'spacer (typically polythene strip after World War Two) to provide an 'air gap', then another layer of polythene insulation, another metalised paper screen, a wrapping of oil soaked jute yarn, a layer of steel wire windings or braid then an outer wrapper of oil soaked jute yarn.
The technologies paid for by the development of telegraph cables were then applied to shore-based wiring. By the later 19th century they were making flexible wire using multiple strands of copper in a rubber sheath, where multiples of these were required they were commonly braided (in the same way as long hair can be braided) and covered with a fine woven cotton sheath. Practical use of electricity in homes and offices probably dates from the electric fan invented by S. S. Wheeler in 1882, this was followed by the electric iron in 1882, the electric stove in 1896, the Singer sewing machine in 1889 and the washing machine in 1907.
Getting electricity supplies to houses and factories was however a difficult proposition (see also 'Appendix One - Fuels (Coal, Gas, Oil and Electricity)' for a description of the various approaches employed prior to the widespread use of sheathed copper cables.
A Mr. Ferranti, the Chief Engineer of the London Electric Supply Company from 1887-1892, developed a high voltage cable for use underground to carry the high tension (high voltage) supply at 10,000 volts. This consisted of an inner conductor of copper tube (about an inch across) wrapped in brown paper soaked in ozokerite (a mineral wax) inside an outer copper tube (also wrapped in impregnated paper) all enclosed in an iron tube. This could only be made in 20 foot lengths (giving over 300 joints per mile) but when the last of it was removed in 1931 it was still functioning perfectly. Paper wrapped cables of this general type were still used into the 1940s although they were by then wrapped in lead to provide the watertight covering. One small point is that electricity runs along the outer part of the conductor, very little passing through the centre, so the use of copper tube saved a lot of money (in copper) and provided the same utility as a solid copper rod.
Making a cable to carry the much higher voltages required by the National Grid with three phases (that is three separate cables) inside a common sheath proved very difficult, it was found that adding a paper wrapper coated with metal as a 'screen' helped and oil-filled cable was adopted with reservoirs at intervals to maintain the oil level in the cable. Some cables use nitrogen gas under pressure in place of the oil. By the 1930s they were able to make a single three core cable to carry the 132,000 volt national grid supplies and single core cables were made to carry up to 250,000 volts.
For runs of any length it is preferable to suspend the bare wire or cables from tall pylons but the sheathed high tension cables are used to cross rivers (where overhead cables would not be practical) and in places where the very high voltages must be run underground. The length of the cable produced since the 1930s is limited only by the maximum size of the drum on to which it can be rolled.
For suspended cables it is common practice to use aluminium for the bulk of the cable as this is much lighter and less prone to breakage's than copper, a steel wire core is used to provide the required tensile strength. The cables used up to the 1950s were only about three quarters of an inch in diameter (about 17mm). This cable is really a form of wire rope and is shipped coiled onto cable drums for convenience.
For all types of cable the normal method of transportation is to wind them onto a drum, this can be a cardboard type for lighter wiring as used in houses, or a whacking great wooden thing for the heavier power cable run under streets and in industries. Some examples of the larger drums are shown in the section 'Wagon Loads and Materials Handling - Wagon Loads - Introduction', further examples are shown below under their respective makers entry.
Modelling a cable works
Cable works tended to be large establishmnts, however the rail access was typically confined to one side of the factory, if we model only this part but use appropriate 'set dressing' elements we can retain the character of the prototype.
Fig ___ Rail access to a cable works
The suggested layout shown below allows for regular traffic run to the main building whilst tanks wagons and coal wagons can be held on the kick back siding. The barrels and cable spools at either end define the purpose of the works, the gantry crane used to lift the heavy cable drums and rolls of paper suggests a substantial industry.
Fig ___ Suggested layout for a cable works
The wire used for carrying the electricity is usually copper, aluminium for suspended cables, which is supplied by the wire drawing works on bobbins. This is loaded onto a stranding machine or into a bunching machine and the appropriate number of wires are twisted together to form a complete conductor. The resulting multi-strand 'wire rope' is annealed (if required) and wound onto a drum, some of this (notably the aluminium type) is sold with no further processing.
The paper used for insulation on high voltage cable is specially produced from selected wood pulp to impart the necessary mechanical and electrical properties. It is supplied in rolls about three feet (1m) long by up to five feet in diameter. This is cut into the required strips by a slitting machine at the cable works. The paper would not be rolled around the works as that would damage it, it could be pulled by men on a four wheeled trolley but by the time of the First World War a small electric truck would be the most likely way of moving them about. The example in the sketch below dates from the 1940s , the roll sits on a platform on legs (known as a stillage platform) and the truck has a simple elevating mechanism to lift it when moving.
Fig ___ Shifting paper rolls
To provide some movement at the works this can be modelled using a thin line to 'tow' the truck unit between two buildings, run round a pulley at each end the unit would trundle back and fore with no complicated switching. Adding additional pulleys would allow it to take a circuitous route between buildings, entering and exiting from various doors. Similar trucks would be used for the spools of wire.
The stranded cable is insulated either by wrapping with paper in a lapping machine or by coating with rubber or plastic in an extrusion machine, the latter may also include a vulcanising process. A metalised paper wrapper 'screen' would be added for lines carrying signals (telegraph and telephone lines for example). The insulated core it is then wound onto either delivery drums for sale or onto process drums for further work.
The rubber would be supplied as a liquid, either in bulk or in drums. The plastic would be supplied as a granular powder and stored in fairly large metal silos at the works close by the building where it was used.
Multiple insulated cores are then laid up (2, 3 and 4 cores are common in power lines) and for heavier cable the spaces between them are filled (typically with oil impregnated jute) so the cable will end up circular in cross section. Additional cables for engineers telephones are often included in power cable runs. This multi-core cable is then coiled onto a drum or coiled down into a tray.
For paper cable this lot is then immersed in a tank, under a vacuum, where traces of water are removed. The tank is then filled and pressurised with the impregnation compound (either mineral oil or a blend of micro-crystalline wax and mineral oil etc.). This is the 'cable compound' or 'electrical oil' delivered in tank wagons (note there are many types of 'electrical oils', this is just one of them).
For power cables the multi-core insulated cable is then sheathed in lead or aluminium for some post war production, the aluminium sheath has the added benefit of being available as a 'ground' reference line as little current is involved. The cable is then wound onto a drum for sale or for further processing if required.
Power cables (especially those to be pressurised with oil or nitrogen) and submarine telegraph cables are usually 'armoured', for paper insulated types a layer of jute impregnated with a with bituminous compound is applied and the cable is then wound with either steel wire or strip. Up to the 1950s a further coating of impregnated jute finished the job. Plastic insulated cables do not need the protective layer of jute over the cores, the wire or strip is applied directly to the plastic sheath. Up to the 1960s the outer covering was often a layer of impregnated jute cloth but by the 1950s a layer of plastic or synthetic rubber (called elastometric coating) was often applied. The cable is then wound onto the delivery drum.
From the 1930s until the later 1960s the cable itself was white on all the examples I have seen or remember. In the 1970s I remember seeing one power cable being laid which had a 'dove grey' outer PVC sheathing.
Before despatch every drum of cable is subjected to electrical tests and examined for correctness of construction and dimensions and in the presence of customer's representatives where this is required. Finally the cable ends are trimmed, adequately sealed and protected with a metal or plastic cap. The drums receive their outer lagging and are then marked and labeled for dispatch.
At the works there would be a number of un-liveried cable drums being used for holding the cable between the various processes as well as drums of finished cable marked up for delivery. Wooden drums had sides of planks, two layer laid at right angles, these can be represented by scribed plastic card disks. The centre of the drum was wooden planks laid across, secured to an inner frame and bolted to the sides. For this you can scribe some tube of suitable diameter (the thicker the cable the bigger the centre has to be).
The cable drums were softwood such as pine, made by timber merchants and supplied to the works. For drums less than eight feet in diameter these can be carried on their sides on a flat wagon, well roped down. The empty drum shown below left would need to be transported vertically on a drop centre wagon. The centre of the drum was quite large as the cable cannot be bent very tightly. The battens to go round the outside of the drum would also be supplied by the timber merchant, probably shipped loose or tied in bundles in open wagons. Fine wire for the cable cores and for the protective metal braiding would also be supplied from the wire drawing works on similar drums, probably about the size shown below right, although for fine wire the centre of the drum could be much smaller. These drums would presumably be branded for the wire drawing firm and be returnable (so you would have out-going 'empties' to handle). If your drums are transported upright you can make any securing 'ropes' from wire and free to rotate, then the drums can have one side unbranded (incoming empties) and the other marked for the wire drawing firm (empties being returned) so you can simply reverse them on the wagon to perform both roles. The same would apply for full drums with the outer battens in place.
Fig ___ Empty cable drums sketched from photographs
To lift the a loaded cable drum using a crane a steel bar would normally be passed through the centre hole and ropes or chains attached to the ends, you cannot feed a rope through as the holes in the sides open into the large space inside the core of the drum. If the drum is large a spreader-bar might be used on the crane hook to avoid the ropes biting into the sides. To move a full drum on site they often used a small four wheeled trolley, many works had a narrow gauge internal railway and the example shown below right runs on such a track (notice how far out the bolts holding the centre spool are, again this drum would not hold as much cable as you might think).
Fig ___ Lifting and transporting cable drums
Again there is the possibility of including movement, a small works engine or tractor towing the drum on its cradle, but reversing this would be tricky for continuous operation.
The markings applied to the drums for shipping varied a lot, some had just the company name around the edge, others had instructions of various kinds added. As you will probably print the drum sides adding the instructions and other complex markings is not a problem, examples of drum markings have been included below at a large enough resolution for use on a model.
The range of traffic that can be justified by an electrical cable firm makes it of interest to a model railway. For one thing they used a lot of rubber (up to the 1960s it was very widely used for insulation), so you could justify a bulk latex tanker. I do not know if any of the companies received deliveries of bulk latex, but you can justify it on a layout if the factory is big enough. The large bogie tanks shown below were in use in the Liverpool area from the 1950's on for bulk latex but more often latex was shipped in wooden barrels and later in suitably coated steel drums.
Fig ___ Bogie latex tank (introduced in 1949)
The specialist oils such as cable compounds, which have a very high flash point, fall outside the Class A and B system, so the rail tanks used could be any colour. In general they all seem to have been rather dull, often red oxide or black. By the mid 1950s Shell lubricating oil and electrical oil tanks were yellow with red and black markings as shown below left (I think they were red oxide with yellow lettering pre-war). The tank wagon shown below right was used to transport a thick oil used in the insulation of heavy duty electrical cable. It is also an unusual example of a non milk six wheeled tank, in the 1950s when this tank was in service they used resin thickened oils for cable compound, which I assume was very heavy. The livery was black with white markings.
Fig ___ Electrical Oils and Cable Compound tanks
These liquids would be stored in vertical cylindrical tanks, some of which would need to be heated as the bituminous compounds used are pretty solid at normal temperatures. The sketch below shows heated tanks of this type as used in a coal tar distillers, the tanks at a cable works would be essentially the same.
Heated Tanks for bituminous compounds
A rather specialised type of cable is 'Mineral insulated cable' , sometimes referred to as MI cable, and sometimes as MICC (mineral insulated copper covered) cable. This consists of one or more metal conductors surrounded, and separated from each other, by an insulant made of compressed inorganic powder (magnesium oxide), the outer sheath being metal (some were supplied with a PVC outer sheath where rust would be a problem). Up to the 1970s copper was used for both the conductors and the metal sheath but from the later 1960s a range of aluminium (conductors and sheath) cables were developed and marketed. It is made in a rather different manner, the conductor is placed inside the tube and packed with the magnesium oxide, this is then drawn to reduce the diameter of the cable, it is semi-flexible and was supplied on drums as for the more common types but requires special tools and connectors (the ends must be sealed to keep out water, up to the 1960s this was done by filling the junction box with pitch). Finished cables are normally made with one, two, three, four or seven conductors, and in sizes designed for 660, 500, 440 or (from the 1960s) 250 volts. Only three companies made this stuff that I know of BICC and Pyrotenax being the most important. This cable was invented in France and Pyrotenax had sole UK manufacturing rights, they started production in 1937, BICC began production in 1953 (I believe Pyrotenax may have merged with BICC in the later 1960s but the brand remained in use). The third company was The Wednesbury Tube Co. Ltd., who marketed through a wholly-owned subsidiary they set up called Mineral Insulated Cables Ltd. The main application for this stuff was in coal mines but it was originally developed as a fireproof cable so it is also used for historic buildings, large blocks of flats and the like and is handy for under-floor heating systems (it lasts indefinitely, which is another plus).
Companies involved in electrical cable manufacture
There were a great many cable making companies in the UK, however by the 1940s many had merged into the larger firms. I will try to find livery details for as many parts of the country and eras as I can, however this may take some time.
Henley's Established in 1837, this firm was one of the major producers of cable in the UK. The illustration below is from the old Airfix telegraph poles kit and I think the livery (if accurate) would date from the later 1950s.
Henley's was absorbed by AEI in 1959 but the name remained in use.
British Insulated Cables Ltd Founded in 1891 by Joseph and Jacob Atherton at Prescot, near Liverpool In 1902 they amalgamated with Helsby Cables, a good move for the latter as British Insulated Wire Company held the British patents for the manufacture of dry-core cable and rubber or gutta-percha insulation for conductors was now being seriously threatened by the cheaper dry-core paper system. The cable drum shown below left dates (I think) from the 1920s and is marked 'British Insulated Cables - Helsby'. The sketch below right shows a drum for export in (I think) about 1939. The logo shown to the upper right of the drum was in use in the early 1930s.
B.I.Cables merged with Callenders Cable Co to form BICC in 1945 (discussed below).
Anchor Cable Co This company was set up in the nineteenth century operating from Leigh in Lancashire. In 1903 they were merged with Callenders Cables but the factory remained in production and the brand was retained until 1950. In the 1950s (I think) BICC set up a tall tower on the site, this contained steel tubes flooded with superheated steam used to vulcanise the rubber coating on cables. As I understand it the change to PVC in the 1960s meant the tower was no longer used, but it remained in place for a few years after that (there was only one other such tower in Europe). In 2002 the Leigh site was purchased from BICC (the Leigh plant was then trading as Prysium) but production continued until 2006 (the heavy lorry traffic was annoying the locals) and it is now a business park.
Callenders Cable & Construction Ltd Based in Falkirk, Scotland, this firm started life as Callenders Bitumen Telegraph and Waterproof Co Ltd. but the name changed in the 1890s. They made cables at a plant in Erith near London from the later 1890s and formed part of BICC in 1945. The illustration shows a drum photographed in the 1930s.
Liverpool Electric Cables Company Liverpool Electric Cables Company was absorbed by AEI in 1958. The livery shown left dates from the 1940s but may well have been standard for many years at that time. The text in the box reads 'Must not be dropped when unloading'. The drum shown right is the early post-war livery.
Telephone Cables Ltd Definitely operating in the 1930s Telephone Cables Ltd was taken over by AEI in (I believe) in the 1960s, the illustration shows a drum photographed in the 1950s but I believe it would equally serve for a pre war drum.
Aberdare Cables Ltd I believe this form was set up in the town of Aberdare (Mid Glamorgan, Wales) in the later 1930s, they certainly had a large factory built there in 1937/38. They became part of Pirelli Cables, which now trades as Prysmian cable.
Pyrotenax Set up in 1937 to manufacture fireproof 'Mineral Insulated Cable', mainly for use in coal mines. They were based in based in Hebburn-on-Tyne and until the 1950s they were the sole UK and commonwealth supplier. In 1952 the original patents expired and in 1953 BICC began making mineral insulated cable, so Pyrotenax diversified into other forms of armoured cable, however mineral insulated cable was a valuable export commodity for the UK as recently as the 1970s. In addition to manufacturing MI cable, Pyrotenax also produces many of the electronic controls and temperature monitoring accessories used in snow melting, pipe tracing, floor warming and de-icing. They merged with BICC in the later 1960s, but the brand remained in use as BICC General Pyrotenax Cables Ltd. In 2002 Pyrotenax became part of the large American group Tyco Thermal Controls. In 2004 the 'former BICC Pyrotenax site' at Prescot was being redeveloped as a light industrial and retail park.
Wednesbury Tube Co. Ltd. I am not sure when this company was formed, or what happened to them but they produced mineral insulated cable and marketed this through a wholly-owned subsidiary they set up called Mineral Insulated Cables Ltd.
Aluminium Wire and Cable Co I was under the impression that this company was set up in 1966, however a company with the same name is listed on the Gracies Guide website (see Appendix XXX Links to useful websites) which was established in 1946 in Swansea and within a few years was supplying overhead cables. A company was still trading under this name into the later 1970s but I am unsure as to its subsequent fate. I believe the cable drums date from the 1960s. Note the different styles of drum lettering co-existed.
Telcon This firm was probably the most important undersea cable maker in the UK (they traded under this name from the later 1850s until 1959).
Commercial Cable Company Based in Weston this was a less well known company but a major player in under sea cables. CCC was bought by the American firm ITT in 1927, their first purchase in the UK. They sold it to Western Union in 1988. CCC eventually became in its final years a computer service and value added messaging outfit. They obtained the first value added licence in the UK, in part compensation for the loss of their cablegram licence as the then conservative government closed out all US cable subsidiaries to make way for the float of BT.
Associated Electrical Industries AEI was one of the two major companies in the UK, originally formed from The Edison Swan Electric Company in 1929. In 1953 AEI acquired Siemens Bros. (already a major cable manufacturer), taking over the Liverpool Electric Cables Company in 1958 and W. T. Henleys (another long established cable making company) in 1959. Of these the W T Henley brand was retained, I believe the LEC brand was dropped and I believe the Siemens brand was thereafter associated with fibre optic cable systems. At some point (I think in the 1960s) AEI took over Telephone Cables Ltd and The London Electric Wire Co. In 1967 the General Electric Company took over AEI Cables and Hackbridge Cables Co., culminating in the formation of AEI Cables Ltd in 1968. I seem to remember the AEI logo on drums but I have not found any photographs to confirm the details.
In March 1997 the GEC Wire and Cable Group, of which AEI Cables was part, was acquired by TT electronics plc (then called TT Group plc).
British Insulated Callenders Cables Ltd (BICC) This company was formed by a merger in 1945 of British Insulated Cables Ltd (started making cable in 1890) and Callenders Cable & Construction Ltd (who made cables from the later 1890s). Both firms already had several subsidiaries and BICC was for many years one of the biggest companies in the UK. The sketch below shows the livery on a BICC drum in the later 1960s, the logo shown on the right was in use on their stationary (but not I think on the drums) in 1949. I believe BICC initially had their name in full round the edges of the drum, this changed in the post war era to just BICC as shown on the illustration.
In 1999 BICC Energy Cables was bought by General Cable Corporation (originally incorporated in New Jersey, USA, in 1927). The Company changed its name to BICC General and added Anaconda®, BICC® and Brand Rex Brands to its product line (Anaconda produced (I believe) wire reinforced tubing, some has an outer wrapper of flat metal strip, one use being for handling refrigerated liquid gas).
Pirelli Cables, now Prysmian cable. This firm set up a British branch in 1914 and produced cable in the UK for many years, although the exact location of its factories is less well documented. In the later 1990s Pirelli set about what it called 'a targeted campaign of acquisitions' across Europe. The parent company, Pirelli Cavi e Sistemi, bought out the power cable businesses of Siemens AG, BICC and Metal Manufacturers Ltd, and two NKF factories. In 1997 a new company called Prysmian (indirectly controlled by The Goldman Sachs Group Inc. of the USA)bought out the Energy Cables and Systems and Telecom Cables and Systems activities of Pirelli & C. S.p.A. In 2007: Prysmian became a listed company on the Milan Stock Exchange.
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