The power system is severely constrained due to the loss of additional generating units from Eskom's power station fleet, reduced imports and the extensive use of emergency reserves.

"This has necessitated the need for Eskom to declare an emergency in terms of the approved regulatory protocols, as a measure to protect the national electricity grid.

We have alerted our key industrial customers and have required them to reduce their load by a minimum of 10% as from 2pm today," said the power utility.

The emergency is in place until 9pm tonight, after which it will be reviewed to determine the way forward.

Eskom said every effort will be made to avoid load shedding.

"While we will make every effort to avoid load shedding, we are hopeful that by applying these measures, coupled with support from all electricity consumers, we will achieve the required load reduction necessary to protect the national grid," said Eskom.

The power utility called on all its commercial customers, particularly shopping centres and retail outlets, to immediately switch off geysers and to adjust air-conditioning temperature levels to 23⁰C.

It also appealed to workers leaving office buildings this evening to switch off lights with the exception of the security lighting, and avoid leaving air-conditioning on overnight.