The main union involved said that about 60 percent of the votes counted so far from its ballot were in favour of Eskom's 10.5 percent wage offer. One of the other unions gave a similar estimate for its own vote count.
But both unions said acceptance was on condition that a firmer deal for a housing allowance be reached at a meeting with Eskom on Wednesday. The unions expect a final tally of votes before the meeting starts.
The threat of power cuts at mines helped drive up the price of platinum last week and to push the rand to a three-week low as investors feared it could harm an economy in its first recession in 17 years.
"So far 60 percent say we should accept the offer and not go on strike, even though we do not have responses from two key areas," National Union of Mineworkers (NUM) chief negotiator Paris Mashego told Reuters.
"As leaders we are pushing for acceptance of the offer."
He said the strike would be off if 80 percent took the deal.
The NUM, which has about 16,000 members at Eskom, close to half the utility's employees, as well as smaller unions Solidarity and the National Union of Metalworkers (NUMSA) were originally pushing for a 14 percent wage hike—about double the inflation rate—and more for a housing allowance.
Mashego said members want a deal to settle the housing issue by November, and not February as proposed by Eskom.
Challenge
Bennie Blignaut, Solidarity's head negotiator at Eskom, said so far about 60 percent of its 5,000 members were also in favour of the utility's offer.
The metal workers’ union, NUMSA, said it would have a clearer picture by early on Wednesday.
A power strike would be a challenge to President Jacob Zuma's authority as he tries to lead South Africa through the recession and defuse anger in poor townships.
A strike at Eskom would be the latest in a wave of industrial action that has led to above-inflation settlements, including agreements in the gold and coal industries.
The government also awarded a 13 percent wage hike to council workers last week, nearly double the inflation rate of 6.9 percent for June, to end a 5-day strike.
Eskom generates 95 percent of South Africa's electricity and 45 percent of Africa's power output.
Blackouts early last year temporarily crippled mine output, metal smelters and manufacturing, denting economic growth in South Africa, by far the world biggest platinum producer and also a major gold supplier.
After rising as high as $1,290 an ounce last week, platinum traded at around $1,240 on Tuesday.
