"The assumption has always been that because Saftu is perceived as Numsa-dominated ... it can not have people coming out in numbers in various provinces as we saw...."
"This is a fight about the life and death of trade unionism itself in the country", SAFTU Secretary-General Zwelinzima Vavi said.
The strike is in opposition of the new National Minimum Wage Bill and other changes to labour laws.
Saftu will also have a case to make to rival federations Cosatu, the Federation of Unions of SA and the National Council of Trade Unions regarding participation at the National Economic Development and Labour Council (Nedlac).
During the last few hours messages circulated on social networks claiming that the protests will be violent, although according to Saftu's acting spokesman, Patrick Craven, these messages are malicious and unfounded.More news: What comes after commission's report on college basketball?
Passenger Rail Agency of South Africa (Prasa) spokesperson Nana Zenani said trains were expected to keep operating across the country.
Meanwhile, talks to end the bus strike were still underway late on Tuesday night but even if they were settled, the NUMSA component would still join the SAFTU strike, as an affiliate to the fledgling trade union federation.
"There will be absolutely no danger", he said, adding that people should disregard hoax messages warning of mayhem.
On a tweet posted yesterday, the federation said, "On the 25th, SAFTU, its affiliates and our allies in civil society, will be on the streets of South Africa in a general strike in protest against the biggest attacks on working-class people".
In Johannesburg, unions will assemble in Newtown Precinct Park while those in Cape Town will meet at Keizersgracht. In East London, marchers will move to the department of labour while in Queenstown, the march will take place outside the department of labour.