Nearly 50 Sars offices have been affected by the pickets involving workers affiliated to Nehawu and the Public Servants Association.
Eskom said it was still required to continue implementing load shedding for the foreseeable future until the situation had been normalised.
The National Union of Mineworkers and the National Union of Metalworkers of South Africa plan to convene a shop steward council in the morning to receive feedback from branches on the proposal that could help lift some of the pressure on the national grid.
Negotiations between the power utility and unions resumed on Friday morning after reaching a dead-end last week.
The Massmart Group includes Massbuild, Mass Warehouse and Masscash owning stores including Game, Makro, Builders Warehouse, Rhino Cash & Carry, Jumbo Wholesale and Shield.
Workers downed tools earlier this month demanding an 8% salary hike.
Thousands of Numsa members are marching from Mary Fitzgerald Square in Newtown to the offices of the Metals and Engineering Industries Bargaining Council in Marshalltown.
The unions said they were in consultation with members to prepare for a possible strike that could cripple the economy and services including the health sector.
The union said the negotiations took a turn after Samwu and the Independent Municipal and Allied Trade Union received an offer.
Disgruntled employees protested on Monday over delays in the processing of their January paychecks.
Employees downed tools over unpaid salaries on Monday morning. Some took to the streets in protest and spread rubbish in parts of the city.
Workers were demanding an increase of 9% while the university was offering 6.3%.
The National Union of Metalworkers of South Africa is leading the industrial action.
Numsa's Phakamile Hadebe said the university was violating the principle of equal pay for work of equal value.
The union has been on strike for a week over pay and office space at Metrobus offices.
They are demanding an 8% increase, while the company is offering no increase.
The doctors warn that current fuel shortages and poor pay may still hamper their ability to report for work.
Last week, the court ruled in favour of the union saying its strike at the gold mine is legal.
