Minimum width of 15 meters, however this could be extended depending on the gradient of a location, wind conditions, combustibility of the fuel material, as well as flame height conditions.
Full 2004 SANParks Report here.
Full 2017 Santam Report on "Mega Fires".
The firebreak should be wide enough and long enough to have a reasonable chance of preventing a veldfire from spreading.
Check that the firebreak does not cause soil erosion.
Ensure the firebreak is free from flammable materials.
Maintain vegetation height as low as possible, alternatively completely removing
vegetation in the firebreak area.
Clear out the combustible material derived from creating the firebreak so that it cannot be used as fuel in a fire.
On the slopes of Table Mountain, firebreaks are created by brush-cutting versus controlled burning in some instances, especially in fire season. This is due to the fire in this area having run-away properties when considering the type of unique (and dry) vegetation in this mountainous range. Firebreaks should be done in consultation with the local Fire Protection Association and the Fire Services closest to you. They will be able to provide the best advice for your unique ecological area.
In general, unless authorised by the Fire Services explicitly, no fires are allowed on Table Mountain.