South Africa's State-owned electricity company Eskom continued implementing rolling blackouts on Tuesday as its crippled generating units struggled to supply enough power in a crisis likely to further hurt the ailing economy.

In its latest statement Eskom said it was implementing "stage 2" load-shedding until 9 am on Tuesday morning, which effectively involves suppressing 2 000 MW of demand at a given time to avoid collapsing the national grid, after applying "stage 4" rotational powercuts which require taking 4 000 MW of demand off the grid for about 14 hours on Monday.

"Eskom’s maintenance teams are working round the clock to return generation units to the electricity system," it said.

"We remind customers that load-shedding at Stage 4 is no cause for alarm as the system is being effectively controlled. Load-shedding is a highly controlled process, implemented to protect the system and to prevent a total collapse of the system or a national blackout."

Eskom supplies 95 percent of South Africa's electricity needs but has struggled to do this in recent years, largely due to cash constraints and a failure to maintain its infrastructure. Several former senior officials have also been forced out after being implicated in corruption.

The main national opposition Democratic Alliance said it would on Tuesday engage with some Johannesburg residents on issues they faced on a daily basis "especially load shedding, which then leads to jobs-shedding".

"The collapse of Eskom and its effects on the economy can be laid squarely at the feet of Eskom," it said in a statement.

Utility Johannesburg Water warned the electricity woes would affect water supply.

"In the event of load-shedding for the duration of four hours and more, pockets of areas will have water shortages of even low pressure because Johannesburg Water uses electricity to pump water from the reservoir," it said.

The National Council of Societies for the Prevention of Cruelty to Animals said it had grave concerns for agricultural beasts that depended on electricity for survival.

"In any intensive farming system, animals are dependent on ideal environmental conditions to survive – these conditions often depend on a constant supply of electricity," it said.

"Electricity plays a crucial role in animal farming. It drives the system and equipment that creates the ideal environment to keep the animals in full health and vigour. Lighting, heating, ventilation, electric motors which run feed lines – electricity is at the core of a productive intensive farming system."

"The NSPCA strongly urges Eskom to take serious cognisance of the concerns raised, and to consider the welfare of the sentient beings that rely on a constant electricity supply to survive," it added.