Organisers of the two-day national convention which begins at the Sandton Convention Centre on Saturday morning say it has been oversubscribed by 2 300 people - and more are still expected.
About 4 500 delegates were expected but so far the event has been oversubscribed by 2 300 people, a figure organisers said was likely to increase.
The additional people were made up of delegates who had arrived in Johannesburg from various provinces without having pre-registered.
Organisers said an overflow area was set up at the Johannesburg stadium for people who did not have accreditation to attend the convention.
A live video feed has been set up for members of the public to watch proceedings of the convention.