Power utility Eskom on Wednesday called on consumers to switch off geysers, pool pumps and all non-e.
The union federation's top leadership were retained unopposed while the fractured affiliates united in song, praising the president.
All of Cosatu's national office bearers - president Sdumo Dlamini, first deputy president Tyotyo James, second deputy president Zingiswa Losi, general secretary Zwelinzima Vavi, deputy general secretary Bheki Ntshalintshali and treasurer Freida Oosthuizen - retained their positions.
This is the same group that stood steadfastly behind Zuma's elevation to the top job at both the ANC and the country.
Zuma's speech also struck the right chords with the delegates at Cosatu's 11th National Congress at Gallagher Estate in Midrand, as he emphasised the importance of the alliance.
But Zuma also warned that the ongoing strikes within the mining sector have the potential of plunging the economy into another recession, which would cost millions of jobs.
He cautioned that the ongoing impasse at Lonmin mine in Marikana and other mines was not only a problem to the mining industry, but had a detrimental effect on the entire economy.
"The impact goes beyond the mining sector. The manufacturing sector, especially the Fabricated Metal Products sector, is already showing signs of strain. We cannot afford to go into a recession and revert to the 2008 and 2009 period where the country lost close to a million jobs, which we are still battling to recover," Zuma said.
The ongoing work stoppages in the platinum and gold sectors in the past nine months had already cost R4.5-billion in lost production.
Zuma commended Cosatu for its "maturity" in retaining its leadership without contest, adding that the outcome was a lesson to the entire alliance. He also took the opportunity to attack his political detractors, whom he accused of using the Marikana tragedy to score cheap political points.
Comparing government intervention in Marikana to apartheid was being disingenuous as the government's intention was to stabilise the situation, he said.
Zuma also called on the mining companies to implement the Mining Charter. His speech was preceded by that of Dlamini, who also alluded to the Marikana tragedy .
Dlamini, who has emerged as Zuma's key supporter in Cosatu, cautioned delegates that tensions within the federation were tactical and should not be regarded as "strategic differences."
"We will not go to Mangaung divided, but we will go there with a clear class agenda to defend and advance the progressive outcomes of Polokwane," Dlamini said.