The longest restriction imposed was six hours, eighteen minutes, the average duration being of the order of two and a half to three hours. The response when load shedding became necessary was excellent and was generally achieved with 15 minutes of loss of generating plant on peak, but frequently it was possible to anticipate excessive loads and impose the necessary target restrictions in advance.

As a result of this shortage of generating plant to cater for the post war expansion, either new projects or expansion of existing businesses were delayed, but it was possible to give realistic dates for commencement of power supplies and thus applicants were able to defer capital expenditure and other commitments accordingly.

Total units showed an overall increase of 54% during the period 1950-1955, but though this was a considerable achievement in view of the shortage of plant, it must be borne in mind that the period was also utilised to the full for the opening up and development of a number of new mines which were brought into production after the restrictions were lifted after the winter in 1955.

Although there were these restrictions in the use of power, the development of the Undertaking continued and with the expansion of the Orange Free State and Klerksdorp Mines, the construction of the Vierfontein power station provided welcome reinforcement to the supply networks to these two areas.

Because of the relative distances and loads involved, the power station was planned for dual transmission voltages, 132 kV for the supply south to the Orange Free State mining area and 88kV for the Klerksdorp area and the establishment of the mines in the Stilfontein area, that it became a more economic proposition to supply this load at 132 kV to a 132/88kV distribution station (Carrdell), than to multiply the number of 88 kV lines, and it also provided a base which to supply the Lichtenburg area at 132 kV to replace the 88 kV supply to the area from the West Wits station.

The early 1950’s also saw the establishment of the Rural Electrification Department of the Undertaking. Up to that time very little rural electrification had been undertaken, what little development there had been in the embryo Sandton and Randburg Municipalities of today being carried out by the Germiston and Georgetown Lighting Department; this Department also being responsible for the urban reticulation within the Germiston Municipality.

With the takeover of this responsibility by the Municipality themselves in 1951 and an approach by a number of farmers in an area midway between Alberton and Heidelberg regarding the possibility of a supply of electricity, the Rural Electrification Department was established on the 1st December 1951, to provide supplies to all small consumers outside municipal supply areas.

At that stage they were unaware that the then rural areas immediately north of Johannesburg would develop into the vast municipal complexes of Sandton and Randburg which, with their tremendously rapid development, together with that of the other areas contiguous to Johannesburg and the adjacent Reef municipalities had hampered to some extent the provision of supply to the more distant rural areas.

With the further development of particularly the mining industry due partly to new uranium production, the establishment of further generating stations became necessary and coincidently the Taaibos and Wilge stations were constructed over this period 1954-1958.

While the output of Wilge situated some 20 kilometres east of Witbank fed into the eastern sector of the system by means of a loop of the Witbank Stepdown 132 kV lines, Taaibos, situated some 18 kilometres south of Vaal power station on the Clydesdale Colliery, was used mainly to reinforce the supply into the Far West Rand area where the loads of the newer mines such as Doornfontein and West Driefontein, were starting to assume considerable proportions and were resulting in the capacity of the original 88 kV transmission becoming inadequate.

Initially four 132 kV lines were built from Taaibos into the Far West Rand each terminating on a 90 MVA 132/42 kV transformer at distribution stations strategically situated in relation to the load, this being followed later by the construction of two additional 132 kV lines from Taaibos and the provision of 132 kV busbars at the distribution stations together with 132 kV switchgear on the stepdown transformers and 132 kV interconnectors between the distribution stations.

When the large power requirements of Western Deep Levels became known it was decided rather than supply the loads at 42 kV from the nearby distribution stations, to incorporate the substations in the established 132 kV network and to step down directly to the consumer’s voltages, i.e.11 kV and 6,6 kV.

It should also be noted that the introduction of a 312 kV network into this Far West Rand area provided a convenient point for the initial 132 kV transmission to the Rustenburg area in 1959, which initially had been supplied by means of a light 88 kV line from the West Wits Distribution Station, but which because of the increase in platinum loads in the area, was becoming inadequate.

While the 1950’s were marked by curbs on development imposed particularly by the shortage of generating capacity, the 1960’s heralded in a period of widespread development in all sectors.

The impetus of the expanding economy was already being felt in the latter years of the 1950’s but expansion had been generally limited to a few particular areas, e.g. the OFS and Klerksdorp gold fields, but the 1960-1970 period saw the Undertaking develop in all directions.

A historic year in the growth of the Undertaking was 1961 when the maximum hourly demand in reaching 2016 MW, topped the 2000 MW mark for the first time, the figure of 4000 MW having been exceeded in 1972 for the first time, an average rate of growth over these last eleven years of approximately 6.5% which, in view of the closure of a number of gold mines on the Far East Rand in the last few years, was considered as very satisfactory.

The load growth of the OFS Gold fields had, towards the end of the 1950’s, indicated that the 132 kV transmission already provided would soon be both inadequate and uneconomic and with the establishment of Highveld power station built adjacent to Taaibos, it was decided to build two 275 kV lines from Highveld to a new distribution station to be known as Everest which was to be connected at 132 kV to the already established distribution stations around the gold fields, i.e. Virginia, Alma and Grootkop, these lines being commissioned during 1959, and were the first transmission lines of this voltage in South Africa.

Following requests for power from a number of municipalities in the south-eastern Free State, considerable expansion in this area took place. The already established Virginia – Senekal 88 kV line was extended in 1960 to provide supply to the municipalities of Marquard, Clocolan and Ficksburg, while in 1961 this was followed up by the provision of supply to Bultfontein, Excelsior, Tweespruit, Wepener, Dewetsdorp and Edenville, with Thaba’Nchu following in January, 1962. It is interesting to note that in 1948 when the first power line was built to the OFS Gold Fields, Parys was the only municipality in the Orange Free State Undertaking and that by early 1962, a total of 31 local authorities in that province obtained their electric power requirements from this Undertaking, this number having increased by the end of 1972, to 40.

With construction of the Carrdell – Watershed (Lichtenburg) 132kV line network in the area which was supplying the White’s and Pretoria Portland Cement companies at Lichtenburg and Slurry respectively, together with the municipalities to Lichtenburg, Mafeking, Zeerust, Coligny and Venersdorp.

Following successful negotiations, a new 88 kV line some 190 kilometres in length was built in 1962 to supply the municipalities of Sannieshof, Delareyville and Vryburg. In addition in 1962, Bloemhof Municipality obtained a supply from the Undertaking from a 60 kilometre extension to the existing 88 kV line supplying Wolmaransstad and later in 1965 a further extension from Wolmaransstad was constructed for supply to Schweizer Reneke.

To the east, expansion was also in progress with the construction in 1964 and 1965 of some 250 kilometres of 88 kV line to supply the South African Railways Union – Volksrust electrification scheme which enabled the Undertaking to supply the municipalities of Greylingstad and Standerton, the latter municipality, although in the Undertaking’s area of supply, having previously obtained their electricity requirements from the Eastern Transvaal Undertaking.

Along the Witwatersrand itself considerable expansion was taking place both with regard to municipal and industrial load, and in the latter field, new or additional large supplies were given to African Explosives for their new Nitrogen Plant, to SA Pulp and Paper for their new Enstra Mill and to Electrolytic Metals and Palmietfontein Chrome, Iscor Vanderbijlpark, Amcor, Dunswart, Scaw Metals, Union Steel, to mention a few, together with numerous smaller industrial supplies.

Obviously with the growth that was taking place, considerable reinforcement was required to meet the loads that were increasing so rapidly in most areas, and with the commissioning of Komati power station some 36 kilometres south of Middelburg at the beginning of 1962, the start of a 275 kV backbone for the Undertaking was commenced that was to stretch from Komati via Nevis (near Springs) for supply to the Far East Rand complex, Snowdon (west of Heidelberg) for supply to the near East Rand complex, Highveld and Everest (between Welkom and Virginia) for supply to the OFS Goldfields by the end of 1962. An extension to this backbone via two 275 kV lines Highveld – Scafell was completed in 1963 to reinforce supply from Scafell to the Far West Rand area, where the load particularly of the goldmines was increasing rapidly with the development of Western Deep Levels.

Seven new traction stations in the Undertaking’s area of supply were equipped and commissioned for the Klerksdorp – Kimberley electrification towards the end of 1964,and four further stations to serve the new rail link between Houtkop and Potchefstroom and some 94 kilometres 88 kV line were commissioned early in 1965.

The decision to construct a major 400 kV transmission system from the power stations situated in the Eastern Transvaal Coalfields to the Cape with major distribution stations at selected points along its route provided the Undertaking with two convenient additional input to cater for its growth of load.

The first was to be Atlas Distribution Station situated near the Vaal Dam and very close to the route of Snowdon – Highveld 275 kV lines so that by looping these lines into Atlas and the completion of three Camden – Atlas 400 kV lines in 1967, gave considerable reinforcement to the supplies fed from Snowdon and also from Highveld. It should be noted that the 720 MVA 400/275 kV transformers installed at Atlas were the largest transformers by far, in the country at that time.

With the loads being notified for new fold mining consumers in the Far West Rand such as kloof, Elsburg and East Driefontein and in addition, the platinum mining loads in the Rustenburg area, it became very apparent that the 132 kV transmission to the Far West Rand area from Sarfell was becoming inadequate and accordingly with the major input point at Atlas available, it was planned to build two 275 kV lines to a new distribution station to be known as Bernina, in the Far West Rand area and the Bernina Distribution Station was commissioned in April, 1969.

Coincident with this work the 400 kV system was being extended further southwards towards the second major 400/275 kV distribution station on its route to be known as Perseus. This station is near Dealesville in the Orange Free State and was commissioned in 1969, and by means of looping into it the Everest – Kimberley 275 kV line, Perseus is able both to supply to the OFS gold mining area (via Everest) and also to the Cape Northern Undertaking at Kimberley.

While this major expansion and reinforcement in the Eastern, Western and southern sectors was taking place, the northern areas were also awakening.

Following a tentative enquiry regarding the possibility of providing supply from Warmbad, it was felt that this was likely to be the forerunner of major development in the Northern Transvaal and accordingly it was planned that a 275 kV line should be constructed from Esselen Distribution Station to Warmbad, work commenced on this project in 1965.

This 275 kV line was initially operated at 88 kV and supply furnished to Warmbad in May 1966, and was operated in this manner from some 21 months. In the meantime, as hoped, negotiations had been completed with Pietersburg Municipality for a supply at Potgietersrus, which Pietersburg were supplying and in February 1968, the Esselen – Warmbad line was converted to 132 kV operation, the 132 kV substation at Warmbad commissioned together with the Warmbad – Potgietersrus 132 kV line from which a temporary supply at the latter point was made available.

The development was not by any means complete in this area and even as the above supplies were being given, the 132 kV line to Potgietersrus was being extended via Pietersburg to Louis Trichardt, a distance of some 110 kilometres and supply to this municipality was furnished towards the end of 1968.

Following the application by a large number of farmers in the Brits District for supply, the 88 kV system was also extended north to provide a convenient step-down station near Brits to supply their needs and following this development, a new supply to the Brits Municipality which had previously been furnished by the Pretoria Municipality, was made available. These developments in this particular area have resulted in a very large and successful rural scheme and some 1 300 rural consumers were not supplied in this particular area.

In the north-west too, large scale development was in progress. The platinum market was extremely buoyant and the established Rustenburg Platinum mines was expanding, while Impala Platinum and Western Platinum Mines were commencing operations. To meet these large load increases a second Doornfontein – Trident 132 kV line was constructed and completed in January 1969, to provide a more reliable and safe supply, but this proved inadequate and accordingly further reinforcement was planned, i.e. a 275 kV line from Bernina to a new 275/88kV station (Trident) outside Rustenburg. This 275 kV line and the new station was completed in September 1971, just in time for the platinum market to collapse and loads were curtailed considerably, and a number of other major system extensions in that area were accordingly deferred.

In accordance with the government’s policy of aid to neighbouring countries, very amicable discussions and negotiations were carried out with the Lesotho Electricity Corporation and with the backing of both Government, a supply was made available in April 1968, to Lesotho by means of an 88 kV line from Ladybrand to Maseru, and this was followed in 1970 by a further supply to Lesotho at the border post adjacent to Ficksburg.

As a result of the agreements reached with the municipalities of Johannesburg and Pretoria, the fact that the original 88 kV “fan” lines from the south into the Central Witwatersrand were becoming completely inadequate and a decision to take supply from the Cabora Bassa Hydro-Electric Project in Mozambique was made, a start on the Apollo distribution Station began in 1969.

With the commissioning of the first stage of the Cabora Bassa Project in 1975, the dreams of the pioneers of the Old Victoria Falls and Transvaal Power Company didl in part come true as they had too visualised the transmission of power from the dammed up waters of the Zambesi – though they had their eyes on the Victoria Falls itself as the power source.

Unfortunately due to both steel and cement shortages, it was not possible to commission the first 400 kV line to Apollo from Hendrina Power Station until the middle of 1971, the second line being completed early in 1972.

The above shortages of steel and cement also affected the 275 kV lines between Apollo and Jupiter Distribution Station near the Johannesburg/Germiston boundary, whose commissioning was delayed until January 1972. This latter station now supplied the Germiston area and certain mining loads close by, and early in 1973 was the source for the first major input to Johannesburg and later for supply to the Alberton area.

Apollo would also in the future be the point of supply for the new 400kV system to the Western Transvaal via Pluto Distributon Station where it tied into the present Bernina-Tridant 275 kV line for supply to the platinum mining areas north of Rustenburg and the gold mining areas of the Far West Rand and then to Hermes in the Klerksdorp area to bolster the supply to this gold mining area.

In addition, from Pluto Distribution Station a 275 kV line was envisaged to the Lichtenburg area to reinforce the supply to the cement procedures and other consumers in that area.

Before leaving the present era, one must make mention of the supplies to Iscor at their Vanderbijlpark steelworks, the 132/33 kV supply to their combination mill made available in 1970, together, in the same year, with the 275/33 kV supply via two 90 MVA transformers at the Olympus substation for supply to their two new 60 MVA are furnaces; the supply to the National Petroleum Refinery at Sasolburg also in 1970, via two 25 MVA 88/33kV transformers; the African Explosives Midland Factory also at Sasolburg; the African Explosives Midland factory also at Sasolburg; the electrification of the railway line Kroonstad – Harrismith in 1971, as also the start on the Pretoria North – De Wildt section in 1971 and 1972; new supplies to various municipalities such as Benoni, Vanderbijlpark, Parys during 1971, to cater for their increase load growth with initial partial bulk supplies to Pretoria and Bloemfontein, the latter from Perseus Distribution Station during 1972, and the extension of the 132kV line from Louis Trichardt to Messina, to name just a few of the larger projects that have recently been completed.

While all this major work on the main system was in hand, the Rural Electrification Department was building up a considerable organisation to cater for the rural and urban development that was occurring.

Due to shortage of capital in the early 1950’s this expansion was at a fairly slow rate and initially work was restricted to extensions to the areas where reticulation circuits had already been started, e.g. Lombardy East, Buccleuch, Morningside, Sandown, Sandhurst and Ferndale together with a small area south of Germiston.

With capital becoming more freely available the tempo of reticulation development was increased and with the rapid development of large townships north of Johannesburg, the resources of the Department were hard pressed to keep pace, but this to a large extent was achieved and in addition supplies were provided to the areas east, west and south of Johannesburg, e.g. Halfwayhouse, Walkerville, Henley-on-Klip, Boschkop/Muldersdrift, Magaliesburg and Brentwood Park.

As the main development in these areas were completed, it was possible to move further afield and today the Rural networks extend from the Balfour/Grootvlei area in the east to the Lichtenburg/Sannieshof area in the west and from the Brits/Northam areas in the north to the Tweespruit/Westminster area in the South.

When one remembers that the total load supplied by this Department in December 1951, when it started its life, was 6 MW and the number of consumers were 1 300, the present load of some 179 MW and some 29 000 consumers represented a considerable and meritorious achievement, particularly as during the latter years quite considerable areas and a large number of consumers had been taken over by various municipalities as their boundaries had been extended.

And now, what of the future! Naturally the long term was extremely difficult to predict, but in the short term the continued expansion of the Undertaking appears to be assured.

While no dramatic upsurge in the loads of the gold mines were expected even as a result of the free market price of gold, the present price appeared adequate to ensure a lengthening in the life of most mines, some only by possibly a year or two, others by a considerable period of a number of what were previously dying mines, resulted in a greater overall load growth over the next few years. With a major increase in the official price of gold, however, a number of new mines would almost certainly start up.

With platinum apparently the most suitable catalyst for exhaust converters for the American motor car industry at this stage, a considerable increase in the load of the platinum mining industry at least for a few years, appears certain and should the European and Japanese governments follow the example of the Americans in legislating against motor vehicle pollution, an unprecedented expansion and consequently growth in the electrical load could occur in this particular industry.

The South African Railways too were embarking on a large electrification programme with the doubling of the number of traction stations between Kimberley and Volksrust, the electrification of the section Kroonstad – Bloemfontein together with the provision of additional traction stations along the reef.

Industrially too, the Undertaking appears well set for the future. Two large 50 MVA furnaces were due for commissioning at African Metals (Kookfontein) towards the end of 1973, with Scaw Metals following in 1974 with a 30 MVA unit. Iscor’s Northern Complex at Vanderbijlpark required their initial supply in 1973, and African Explosives’ new Nitrogen plant at Modderfontein (40 MW) was due to come online early in 1974.

With the above and continued growth expected both from the municipal consumers and also from the continuous Rural development, it would appear that the Undertaking was set fair to continue on the road of expansion on the sound foundations provided in the past.