With regards to the date it came into effect - it could be close to the 3 years depending on when the contractor signed the contract to carry out the electrical installation.

In a Townhouse complex or development of an area it could be an extra couple of years prior , if that makes sense

Extract pasted below

Hopefully you are not signing off a new build in Fairview or Parson vlei as the socket outlets will be the least of your problems


Because this part of SANS 10142 is continually updated, problems can arise
on which version of the standard will be applicable when a contract is
signed. The date of approval of the latest revision or amendment of this part
of SANS 10142 will be the implementation date of the revision or the
amendment. The applicable version of this part of SANS 10142 is the one
with the latest implementation date before the contract date. So contracts
signed before the approval of an amendment shall be carried out in
accordance with the provisions of the unamended standard. If an existing
installation is extended or altered, such extension or alteration shall comply
with the provisions of this part of SANS 10142 that were applicable at the
time of the erection of the extension or alteration

This document was approved for publication in March 2017.
This document supersedes SANS 10142-1:2012 (edition 1.8).
Compliance with this document cannot confer immunity from legal
obligations.
The test report in edition 1.8 may be used in parallel with the test report in
edition 2.0 for a period of 12 months from the date of publication of edition
2.0.

6.15.1.1.1 Except where otherwise specified in this part of SANS 10142,
single-phase socket-outlets for general use (see also 6.14.1.4) shall
a) be of the two-pole and earthing contact type,
b) comply with SANS 164-0,
c) effective from January 2018 all socket-outlet points for new electrical
installations shall include at least one socket-outlet complying with the
dimensions of SANS 164-2. Socket-outlets points may also include
socket-outlets complying with the dimentions of SANS 164-1.