The vulnerability of the municipality’s electrical network was again illustrated as many households had to make do with candles and gas over the weekend.
On Friday, November 28 the main supply cable from Doornpoort substation serving Blanchville, Die Heuwel Extension 1, Clearwater Estate, Jackaroo Park and parts of Highveld Park burst.
“The bursts on this specific cable, which is more than 10km long, has been a chronic problem, especially as the cable is old and prone to developing cracks and during high demand periods or very wet periods, burns at points. Last season we struggled for some time before we stabilise the system. This cable held out well during winter and last Friday was the first major problem this season,” explained the city’s administrator, Mr Theo van Vuuren.
Finding the fault in the 10km cable is not an easy task.
The team had to test the cable from both sides to see which lines were out.
Once the problem line is found, a signal is sent through the line and with an instrument, which is able to pick up the point where the cable is broken, the line is walked. This is time-consuming and also made more difficult if it is raining. The cable is underground and in many cases runs through private property where permission to enter must also be obtained. The task is taken to a higher level of difficulty as in many cases there are trees or structures under which the cable crosses, and the cable may even cross a marshy area or river, where fault fining is very difficult.
When the point where the fault is has been determined, it needs to be excavated as these cables are submerged, they need to excavate and open it up. Once the damage is determined, the team tests the rest of the line, as in most cases when a cable blows it blows in more than one spot.
That is exactly what happened this weekend, the cable blew in two places. The second area was under a bridge, which also made finding it difficult. As soon as the excavations are done, the cable is cleaned and prepared to be joined again. The damaged areas are cut out. These cables have many wires inside and the points on both sides need to be opened and prepared so that a new cable can be inserted and joined with each wire. It often also takes time to secure replacement cables as cables are not the same in all areas and depending on store levels, the team may not have sufficient stock. Luckily this was not the issue this weekend.
When it’s wet like now, measures to dry the cable must also be followed as a cable once breached absorbs water as well. Sealing the joints is time consuming and on average it takes two to four hours per joint.
The first fault was identified on Saturday morning and following that the second fault around lunch time. By 15:00 all areas were excavated and the joints opened and stock ordered. By 21:30 the four joints were repaired and electricity switched back on.
There is no use joining the cable over and over again and the permanent solution in the replacement of this cable, especially a stretch of 4km running through wetland areas.
“We could not do it before as other budget priorities and the high demands on our budget for day to day crisis management and other issues such as water and sanitation, left very little funding for this purpose. However, we have investigated an overhead cable solution and in this week will confirm the viability of constructing a replacement line as this problem will repeat itself especially if we have an above average rainfall period,” Van Vuuren shared some good news.
Residents feeding from Doornpoort Substation were not the only ones left in the ‘dark’ this weekend.
Sunday, November 30 at 01:00 the power went off to Tasbet Park, Extension 41, Klipfontein, Dixon AH and Duvha Park. This was caused by an attempt to steal a transformer which destroyed both the pole and the transformer.
“By 10:00 we succeeded to ring feed all affected areas except Dixon AH as that area can only be restored once that specific point in the line has been repaired,” said Van Vuuren.
This followed on a cable being stolen at Malherbe Substation affecting areas such as Reyno Ridge the previous day.
“It must again be stressed that thieves will go to any lengths to steal equipment. With load shedding and any break in supply, the system is vulnerable and your assistance in reporting suspicious activities will be greatly appreciated,” Van Vuuren commented on the inconvenience caused by the thieves.
The electricity problems did not end there.
As the weekend drew to a close, a cable burn on Sunday affected Ferrobank. This was repaired quickly.
An increase in demand, wet weather and illegal connections were to blame for the power outage at Ridge and Hlalanikahle on Sunday. Because of illegal connections the points where the illegal connections are made, are not isolated properly and the first raindrops lead to power outages.
The problems in Hlalanikahle could not be repaired on Sunday and were only attended to on Monday.
Adding no colour to this already gloomy picture, Eskom said they expect their power system to be constrained for the foreseeable future. Load shedding was implemented this past weekend.
“The system is expected to remain very tight over the next few days. While Eskom will do its best to avoid load shedding, customers can make the biggest impact by reducing their usage throughout the day, including weekends,” the power house said in a statement.
