See section 6.4.5 of SANS 10142-1
It's not recommended, but you can still install it to this day if you're so inclined.
The trouble with opportunity is it normally comes dressed up as work.
I'd test the earth impedance of all the circuits before getting involved in any further work on the installation. There's a few worrying things visible in the pictures, I don't see any CPC's of method of supplying the circuits with an earth. Also the points where the original wiring and newer circuits have been teed off look very suspect.
thanks andy. haven't done the impedance test yet but there was earth on all the plug points. The DB was also using newish CBI cab's so you can't really tell if it was before or after 1994. Maybe that electrician was being a cheapskate
Without diving in to deep, and not having done the inspection, it seems this open wiring breaks a few regulations: (just from visuals)
6.4.5 Open wiring
NOTE Open wiring consists of single-core insulated conductors that operate at not
more than 250 V to earth; however, this is not a recommended installation method
for new installations. Amdt 5
184.108.40.206 Open wiring shall not be installed
a) under thatched or wood-shingle roofs,
b) in parts of a roof space where the working height is less than 750 mm,
c) in roof spaces that are intended to be used (or are used) for storage,
unless the wiring is suitably protected against mechanically damage,
d) within 1 m of a trap door unless the wiring is suitably protected
against mechanical damage, or Amdt 5
e) where it will be in contact with flammable material.
220.127.116.11 Each conductor of an open wiring system shall be visible where it
is installed on, over, or next to beams that can be used for walking on, or
it shall be suitably protected against mechanical damage. Amdt 5
18.104.22.168 Conductors shall
a) be fixed at intervals not exceeding 1,5 m to building elements such as
walls, rafters or purlins, Amdt 5
b) if there is no ceiling, be at least 3 m above floor level,
c) Deleted by amendment No. 5.
d) Deleted by amendment No. 5.
e) Deleted by amendment No. 5.
f) be supported within 600 mm of the point where they enter conduit or
other building elements, and Amdt 5
g) be fixed in such a way that the fixing method does not impair the
conductor insulation. Amdt 5
22.214.171.124 Where conductors enter a conduit, the conductors shall not be
strained. Metal conduit shall project enough to allow a bush and an earth
clip to be fitted. Amdt 1; amdt 5
126.96.36.199 Where the current-carrying capacity of conductors is impaired by
thermal insulating the appropriate correction factors shall be
applied. Amdt 5
(is wood flammable?)
When the conditions are right, it seems to be.
I'm not sure of the date it might have been installed. Is the original wiring all PVC insulated or is there cotton insulated conductors as well? For me I think I'd probably recommend a rewire given that there are already numerous non-compliant issues with the existing installation, looking at the basic nature of the installation I think it would probably be the fastest and cheapest route to compliance all things considered.