Equal pay for work of equal value.

This demand is at the heart of a planned strike by National Union of Metalworkers of South Africa (Numsa) at the University of Johannesburg, which will start on Friday.

Numsa spokesperson Phakamile Hlubi-Majola said the union had served the management of the university with a notice to strike. She said at the core of the dispute was the university's violation of the principle of equal pay for work of equal value.

"There are employees in the security department who are earning lower salaries than some of their colleagues, even though they do exactly the same kind of work and have the same responsibilities.

"This is because the grading system is unfair and we are demanding that it must be immediately overhauled," she said.

Another demand was that all workers must be on the same medical aid scheme, with the same benefits.

"At the moment workers who were insourced in 2016 are not on the same medical aid plan as other staff," Hlubi-Majola said.

She said to make matters worse, the university made no contribution to their medical aid, but contributed to the medical aid scheme of other staff.

"We are calling on the management of UJ to do the right thing and negotiate an agreement which will suit all parties. UJ cannot claim to ‘serve humanity’ when it fails to uphold and respect the rights of its own employees," she said.

Members of Numsa will picket at the university's Bunting Road Campus in Auckland Park between 10am and 1pm on Friday.