THE HISTORY OF THE WIRING CODE AND HOW THIS APPLIES TO OLD INSTALLATIONS
By Chris Koen, Highveld Regional Director, and Anthony Schewitz, Technical Advisor
In South Africa, there have been four Wiring Codes since 1922, which influence the interpretation and application of the rules in today’s code of practice.
This is important when considering the statement on page 3 of SANS 10142-1 Edition 2: “The edition of the standard that was applicable at the date of erection of an electrical installation is to be considered the edition defining the requirements applicable to that particular installation.”
Knowing the history of the wiring codes helps electrical contractors make informed decisions when it comes to old installations and understanding what is compliant, what is not, and what is reasonably safe.
Introduction of the first wiring codes in South Africa
From 1922, electrical contractors in South Africa worked according to the Factories Act, which was their ‘Bible’ until 1940 when the South African Institute of Electrical Engineers (SAIEE) Red Code of practice came into force. There were a number of reprints and, in 1952, the Blue Code was introduced, which was used by many electrical engineers at the time during the development of cities like Cape town, Johannesburg, Durban and Bloemfontein. Interestingly, the Blue Code was used along with the cities’ bylaws, many of which still exist today!
The Red Code didn’t have a ‘foreword’ or ‘scope’ but this changed with the introduction of the SABS’s Blue wiring code.
The SABS formed a working group to better the requirements of this code and, in 1978, the Green Code was introduced and since then, the content has essentially remained the same, but with amendments updating the content from time to time.
In 2001 the SABS changed the colour of the cover to grey (Grey Code) and two years later to black, and it became known as SANS 10142-1. Currently, SANS 10142-1 is in its second edition.
- The Red Code: The South African Institute of Electrical Engineers (SAIEE) (1940 – 1952)
- The Blue Code: Standard Regulations for the Wiring of Premises (1952 – 1978)
- Green Code: South African Bureau of Standards (SABS 0142) (1978 – 2001).
- The Grey/Black Code: South African National Standards (SANS 10142-1) (2001 – current).
This history is important because not every old installation is ‘unsafe’ and the requirements applicable to many old installations can be found in one of these ‘historic’ publications.
Over the next few months, the ECA(SA) will present a series of articles that will cover contentious issues such as main switches, earth leakage devices, the methodology and approach to calculations, amongst others, which will clarify why certain old installations were done differently.
The main switch
When we read about the main switch in our current legislation, the Occupational Health and Safety Act 85 of 1993 states in the definitions:
‘Machinery’ means any article or combination of articles assembled, arranged or connected and which is used or intended to be used for converting any form of energy to performing work, or which is used or intended to be used, whether incidental thereto or not, for developing, receiving, storing, containing, confining, transforming, transmitting, transferring, controlling any form of energy
And, in the Electrical Machinery Regulations within the OHS Act, we read the following, which has more to do with supplier equipment, industrial boards and machinery:
Electrical Machinery Regulations
- Electrical control gear
(1) An employer or user shall provide all electrical machinery with controlling apparatus and protective devices which shall, as far as is reasonably practical, be capable of automatically isolating the power supply in the event of a fault developing on such machinery.
(1) The employer or user shall provide an unobstructed space for operating and maintenance staff at the back and front of all switchboards, and the space at the back shall be kept closed and locked except for the purpose of inspection, alteration or repair. Provided that the requirements of this regulation with respect to the unobstructed space at the back of the switchboard shall not apply in the case of
(a) switchboards which have no uninsulated conductors accessible from the back;
(b) switchboards the switchgear of which is of a totally enclosed construction;
In the General Machinery Regulations, we read:
- Operation of Machinery
(1) An employer or user of machinery shall ensure that every person authorised to operate machinery is fully aware of the dangers attached thereto and is conversant with the precautionary measures to be taken or observed to obviate such dangers.
- Devices to Stop and Start Machinery
(1) An employer or user of machinery shall provide devices to start and stop machinery, and these devices shall –
- be in a position where they can readily and conveniently be reached by the person who operates such machinery; and
- be so constructed and arranged as to prevent the accidental starting of such machinery.
These confirm the requirements for a main switch or device for switching off installations and equipment. The regulations that follow illustrate how the requirements have changed over the decades with regards to the electrical code of practice.
We’ll begin with the current regulations:
SANS 10142-1: edition 2
18.104.22.168. Each distribution board shall be controlled by a switch-disconnector (see 6.9.4). The switch-disconnector shall
(a) be mounted in the distribution board or adjacent to the distribution board in the same room,
(b) in the case of the main or first distribution board of an installation, be labelled as “main switch”,
(c) in the case of a sub-distribution board, be labelled as “sub-main switch” or “main switch” if the board is labelled “sub-board”,
(d) in the case where an alternative supply is installed (emergency supply, uninterruptible power systems (UPS), etc.), be labelled as required in 22.214.171.124, and
(e) have a danger notice on or near it. The danger notice shall give instructions that the switch-disconnector be switched off in the event of inadvertent contact or leakage.
126.96.36.199 Any point of a distribution board that has to be reached during normal operation shall not exceed a height of 2,2m above floor (or walking) level. However, the board may be mounted higher if it can be disconnected from the supply by a switch-disconnector that is less than 2,2 m above floor level (See also 5.3.8(b)). Unless a residential distribution board is housed in an enclosure and direct access cannot be obtained by an infant, no part of an indoor distribution board shall be less than 1,2 m above the floor level and no part of an outdoor distribution board shall be less than 0,2m above ground level.
Accessibility in the code has changed somewhat and in 6.9.2 and 6.9.4, we read that we should cut all phase conductors. In single phase supplies, it must cut the live and neutral conductors, with respect to accessibility and usability. With that in mind, let’s compare the current edition’s fundamental requirements and to the wording in earlier editions specifically regarding the “main switch” and “distribution boards”.
SANS 10142-1 Ed 2
Fundamental requirements regulation 5.3.8 (f)
- Old requirement
Where the distribution board is concealed by a cupboard or other covering, notices shall be in conspicuous places indicating the position of the main switch.
- New requirement
Where the distribution board is concealed by a cupboard or other covering, the notice for live electrical apparatus referred to in annex N shall be in a conspicuous place indicating the position of the distribution board.
In the Red Code, the placement of the main switch was approved by an engineer (engineers had a lot of power in those days with regards to placement and design of electrical installations). This responsibility now falls on design engineers and ultimately electrical contractors who now ensure that the code of practice is adhered to.
Clearance in front of a distribution board
The requirement for clearance in front of a distribution board has changed a lot over the years. In SABS 0142:1978 we read that a space of at least 0.8m in front of each distribution board and, in SABS 0142: 1987, this changed to an unobstructed space.
SABS 0142: 1978
(h) A clear space of depth at least 0,8m shall be provided in front of each distribution board.
SABS 0142: 1987
(h) An unobstructed space with easy access shall be provided in front of each distribution board.
And in 1993’s regulations, “unobstructed space” remains.
SABS 0142 Part 1: 1993
A distribution board and the equipment mounted in or on it shall be so provided and arranged that –
(f) there is an unobstructed space with easy access in front of the distribution board.
Each main and local and local switch-disconnector shall be easily accessible. If owing to the nature of the installation it is necessary to be able to interrupt the supply immediately, the switch-disconnector shall be so installed that it can rapidly identified and operated.
Due to the requirements having changed over the years, it is important to establish the era under which an installation was done. One this has been established, a decision can then be made whether or not an existing installation complies with the general safety principals of the wiring code and can be considered reasonably safe according to the Fundamental Safety Precautions in SANS 10142-1 Ed 2.
For example, the position and location of the main switch (distribution board) might not be in accordance with the current code (SANS 10142-1) but does comply with the code and bylaws that were in place at the time of installation. Therefore, the installation complies with the General Safety Principles in the EIR 2009 (as amended) provided no alterations have been effected in that installation.
We know there are electrical contractors who still operate with an out-of-date version of the wiring code and it is their responsibility to update to the current legislation. The OHS Act and Regulations as well as SANS 10142-1 Ed 2 are both sold at all ECA offices.
The next part of this series will focus on earth leakage devices.
More info: +27 (0)11 392 0000