Load-limiting off to rocky start

Read time 6min 20sec
City Power has rolled out load-limiting across 31 000 households in Johannesburg to avoid load-shedding.
City Power has rolled out load-limiting across 31 000 households in Johannesburg to avoid load-shedding.

Three weeks after the mass rollout of the City of Johannesburg and City Power's load-limiting, some residents have complained about not being fully informed of how the system works, lack of communication and damage to electrical appliances.

Load-limiting is the system put in place to reduce the impact of load-shedding. It can only happen in households with smart meters, which are used to remotely monitor household electricity usage and limit excessive consumption.

According to City Power, if it can reduce the use of electricity via load-limiting, fewer areas will need to be load-shed.

During load-limiting, each household is given capped electricity supply of 21-amps and, if usage exceeds the supplied limit, a series of three-minute-long power cuts will act as a warning before the power is cut off completely.

Aubrey Mochela, GM of IT at City Power, explains the load-limiting system is ideal because instead of being in complete darkness with no electricity during load-shedding, a household in a certain area experiencing load-limiting will at least have lights.

We started by asking what customers would like to see when load-shedding occurs, he says. Having the lights and TV on, and the ability to charge a laptop or cellphone were some of the top priorities.

According to Mochela, a "standard" household would be able to use five kilowatts to boil water, watch TV and have the lights on.

"A kettle takes about two kilowatts; other appliances like your TV and energy-efficient lights should be able to cover the three kilowatts that are left, so combined you would be able to achieve your five kilowatts use.

"We are avoiding load-shedding through load-limiting. Load-limiting is very sustainable and cost-effective and doable in the short-term. Long-term solutions are expensive and have serious challenges," says Mochela.

"You will not have a situation where there is load-shedding and load-limiting at the same time."

However, Blairgowrie resident Harold Fleishman says load-limiting a household's electricity usage to 21-amps is ridiculous because that can't even be used to cook dinner; 21-amps is equivalent to five kilowatts of electricity.

"Using a kettle to boil water already takes 10-amps," says Fleishman.

Fleishman notes the thinking of limiting a household's electricity to save power is logical, but it will only make sense when everyone's load can be limited. Load-limiting works in such a way that only certain people are being penalised, he says.

'Media hype'

Despite the growing outcry from some residents in areas where load-limiting has been implemented, Mochela says it is just "media hype" as City Power has not received any complaints.

But according to some residents, their electrical appliances have been damaged by load-limiting, and they have experienced power outages and no alert messages that load-limiting will happen in their areas.

Lee Crossingham, a resident in Berario, Johannesburg, says they never received SMSes advising when load-limiting will take place. "The remote unit to be viewed in your home does not work and has not worked since installation. No joy from City Power."

He says so far it is only his DStv decoder that has been damaged, while some of his neighbours have experienced load-limiting but have not had technical issues.

Meanwhile, small business owners in Randburg and Berario expressed their complaints in The Star, on Friday. Ronald Bakker, a resident from Berario who runs his business from home, said: "Every night at about 8:30pm the power is switched off by the smart meter, not just when load-shedding takes place but every night.

"We also have a problem that the office server does a shut down every night and now we are struggling to get it started in the mornings. We are running a business and have come to a standstill."

However, Machela insists this is just media hype. "We send our engineers to go and investigate and they find there is nothing wrong."

Councillor weighs in

David Potter, a ward councillor for the City of Johannesburg, ward 102, says the load-limiting deployment has been "horrific".

"The city failed to inform the residents adequately and seems to feel a few radio interviews and articles in the newspaper are sufficient. Councillors in the city who are answerable to their constituents have not officially been briefed on load-limiting and have had to learn via the media about it," he says.

Potter notes that over the last two weeks, he has received many complaints related to load-limiting and power outages. "Residents of Blairgowrie and Randburg suffered during load-limiting, with some properties having taken many days to have power restored."

Mochela admits informing residents affected by load-limiting has been a challenge.

"It has been a challenging process to send SMSes to people," he says. But he notes some people are reluctant to give out their cellphone numbers so they have to use a customer interface unit.

"We have a customer interface unit that comes with the smart meter. That unit receives instructions that we send. Some people do not use it and some did not switch it on and some people just expect the SMS," says Mochela.

Potter notes the load-limiting system could have been better managed if the city had informed councillors before it was implemented. "The City of Johannesburg has been quite proactive in trying to share the load that is available. I think residents would understand what is necessary if they have been consulted and educated."

Power surges

According to analyst and Strategy Worx CEO Steven Ambrose, load-limiting is a blunt instrument, but can be effective if used at scale.

Switching off appliances is annoying and potentially limited in its scale, he says. The sudden on and off of the main power supply to the home may result in power surges.

"Many household appliances are not designed to be switched off rapidly, and together with surges may result in damaged compressors and motors. Ultimately, the smart meter technology has the potential to manage load at scale and can be very efficient if applied correctly," he says.

Mochela says it would take the City of Johannesburg three or more years to wait for every household to have a smart meter. He explains it is also taking into account that a lot of customers don't want to participate and some don't allow City Power officials into their houses for security reasons.

"City Power is able to save 50-megawatts of electricity with the households we are currently load-limiting," he notes.

To date, 90 000 smart meters have been rolled out throughout Johannesburg and more than 31 000 households are being monitored using the load-limiting technology.

The City of Johannesburg plans to install smart meters in 150 000 households by the end of October.

See also