Power cuts hit Joburg

Johannesburg’s City Power started load reduction today in areas of the city to protect the integrity of the grid caused by high demand. This is despite Eskom not declaring any load-shedding.

Load reduction will affect 80 areas in the city from 06:00 to 10:00 and 16:00 to 22:00.

In an interview with Newzroom Afrika, Professor Sampson Mamphweli, who works for the South African National Energy Development Institute, explained the difference between load-shedding and load reduction, saying that illegal connections are a major cause for the latter.

Load-shedding, Mamphweli explained, is switching off the electricity supply to specific areas on a rotational basis.

Load reduction, on the other hand, doesn’t cut off your supply entirely but rather limits the demand for electricity in an area to protect the grid from damage.

This is done by constraining a household’s usage and remotely switching off appliances, such as geysers.

“In some circumstances, [households] can have two [circuit] breakers. The one breaker will allow for a higher capacity and the other a lower capacity,” Mamphweli said.

“During load reduction, [the city] will switch off the higher capacity breaker, and you will remain with the lower capacity breaker.”

“In that case, you will have a 60 Amp breaker and a 20 Amp breaker.”

Concerning the need for load reduction, Mamphweli said that when installed, a transformer’s capacity depends on the area it will serve.

“The transformers are designed for the capacity of a particular area, and then [the capacity] is increased by about 10 to 15%,” Mamphweli said.

He explained that once this additional capacity has been exceeded, which tends to happen in winter, the transformers risk being damaged.

Mamphweli argued that metropolitan areas tend to have many illegal connections, which can reduce some, if not all, the additional capacity of transformers.

A Yeoville councillor, who was also interviewed by Newzroom Afrika, said that hijacked buildings make up some of these illegal connections.

However, many are due to households being unable to pay down their municipal debt, resulting in them cutting corners and connecting illegally.

Mamphweli also stressed that the city has played a role in the need for load reduction.

He said that many areas have outdated transformers because they do not account for the current population, which is particularly prevalent in informal settlements.

“You still have old transformers that were put in place before the areas became densely populated. The city needs to change these transformers.”

Load limiting and switching off geysers remotely

In addition to load reduction in overloaded areas, City Power will also implement load limiting in suburbs with smart meters “to further assist customers in saving energy without switching them off completely.”

Load limiting was previously only applied during load-shedding and was an alternative to up to stage 4.

This is likely why people were willing to join the programme in the first place.

City Power has also threatened to switch off geysers in households fitted with ripple relay receivers.

A ripple receiver is part of a load management system used to control the electricity supply to the geyser during peak hours.

“These ripple relay receivers at different households are connected to at least 69 of our substations, and we can monitor customers’ consumption load remotely,” City Power said.

The power utility said that geysers were among the biggest electricity guzzlers, accounting for up to 50% of monthly household energy costs.

It warned it would switch off households with ripple relay receivers if they reached “high” consumption, without providing further detail.

Below are the 69 substations which form part of the ripple relay programme.