Lighting Archives » Building Regulations South Africa
Apr 202013
 

Electric Cables – What is Legal

conduits On Underlay509 Electric Cables

We get a lot of questions about which electric cables are legal and how they must be installed. So here is a brief rundown of the different types of legal cabling available and the way an installation could be done. There are various accepted methods and we illustrate a general one here. When a builder has to wire a home, he will first lay conduits, which are plastic or metal pipes fixed in place above the plastic damp-proof underlay and the steel reinforcing.  (See the picture above.)

These pipes are layed out according to the house plans and extend upwards from the floor, and will be built into the walls later when the bricklayers start their work. The concrete for the floors will then be placed, and the conduiting will run within the floor slab. From there they can be chased, or cut, into the walls so that they can be routed to various outlet points where plug points and lights are required. The electrician will later pull the wires through these tubes. There are classes of cable that do not need to be encased in conduit and can be chased into, and laid directly under the plaster. Two examples of these are Surfix and Flat-Twin-and-Earth cables. A full specification can be found in the Aberdare brochure below. When the roof is on and waterproof the cables can also be layed in the roof space for overhead lighting and other fittings.

Wiring electrician185 Electric Cables

A qualified electrician gets to work sorting out all the wires that come together at the distribution box.

Be Guided by What the Law Says about Electricicty and Electric Cables

By law a fully qualified and registered electrician must be  responsible for the wiring. It is a good idea for all homeowners to familiarise themselves with, and be able to identify, different types of cable and flex to ensure that all materials used in the installation are up to standard (literally – they need to meet the relevant South African National Standard).The National Building Regulations and Building Standards Act does not cover electricity and nor does SANS 10400. Electricians must comply with SANS 10142: The Wiring of Premises.

Depending on the class of cable the non-conductive insulation material around the wires inside cables and flex are different colours to make it easy to identify them. Green, or green and yellow, is the earth; live wires are brown or red; and neutral is either light blue or black. Once the wiring in a building is complete the entire system must be checked by an accredited person (from Eskom or the municipality/ local authority) who will issue a certificate of compliance.

Aberdare Cables have an excellent brochure (see below) that should help to identify the various cables associated with the electrical installation in a house.

Download (PDF, 2.47MB)

[Note that we have no affiliation with this company and reference to their brochure does not imply any particular recommendation.]

Nov 152011
 

Good Lighting and Ventilation is Vital for Healthy Living

Bathroom173 Lighting and Ventilation

A beautifully lit, airy bathroom.


In terms of the National Building Regulations, all habitable rooms, including bathrooms, showers and toilets (and interestingly enough garages!) must have some form of lighting and ventilation that will enable people to use these rooms safely. The most important aspect is that it shouldn’t be detrimental to the health of those using the room for the purpose for which it was designed.

If bathrooms are cold and perpetually damp, mould will start to form, and this can make people extremely ill. It will also make the room uncomfortable.

Lighting and Ventilation Requirements

Changes to Part O of the NBR (when the legislation was updated a few years ago) include a welcome move from WC (short for water closet – and a very Victorian term) to “toilet”.

There are also quite substantial changes to this section of the regulations. While the lighting and ventilation regulations are generally “deemed to satisfy” if they quite simply meet the requirements of SANA 10400-O, the NBR states that if there is not sufficient natural light from windows in habitable rooms, as well as corridors, lobbies and on staircases, artificial lighting MUST be provided.

Reasons for inadequate lighting might be due to:

  • the size or shape of the room or space, or
  • the use of thick, patterned or opaque glass for windows, which prevents natural light from illuminating the room.

Similarly, if there is insufficient ventilation, artificial ventilation MUST be installed.

Reasons for inadequate ventilation include:

  • high temperatures which could be dangerous to either the safety or health of those using the room,
  • dust, gases, vapour, “volatile matter” or “hazardous biological agents” that might be dangerous to health or safety, or
  • the purpose for which the room is used may make natural ventilation unsuitable or inadequate.

Compliance Required for Lighting

While the Act states that, “Any habitable room in any dwelling house or dwelling unit, or any bedroom in any building used for residential or institutional occupancy” MUST have at least one opening for natural light – even if there is artificial lighting.

Compliance Required for Ventilation

It doesn’t matter where in South Africa you live, any artificial ventilation system MUST be authorized by your local authority (council or municipality, or City) according to their own specific policies and opinions.

This applies to everything other than regular air conditioners and other appliances installed essentially for comfort.

Further, the “rational design” of any artificial ventilation system must be performed or supervised by an “approved competent person”.

Compliance with Fire Requirements

In addition to the general requirements in this section of the Act, all lighting and ventilation must also comply with Part T of the NBR, a very lengthy section that deals with fire protection.

SANS 10400-O

Part O of the “new” SANS were published in January 2011 after fairly substantial updating by the SABS in collaboration with Agrément South Africa, the South African Institution of Civil Engineering (SAICE), and the South African Refrigeration and Air Conditioning Contractors Association (SARACCA).

Requirements specified in the SANS include:

  • general requirements,
  • requirements relating specifically to lighting,
  • requirements relating specifically to ventilation, and
  • requirements for designated smoking areas and smoking rooms.

Natural Lighting

The SANS specify zones of space for natural lighting which are guidelines that should be adhered to. These relate not only to the measurement of openings, but also to the angles of openings, and they specify how various obstructions affect zones of space.

Natural Ventilation

Generally, natural ventilation should be organized so that doors and windows relate to one another in such a way that the room will be effectively ventilated, and it should be at least five percent of the floor area of the room (or at least 0,2 square metres if the room is very small).

But anyone designing a home also needs to take into account the fact that in cold, wet or windy weather, doors and windows will commonly remain closed. This will minimize natural ventilation.

In holiday homes, or buildings that people only use occasionally, doors and windows will usually remain closed for long periods of time. Where weather conditions are very hot and humid, the interior of the building may become damp and mouldy. Airbricks built into the structure help; as do roof vents that provide permanent ventilation, even when doors and windows are closed.

Artificial Ventilation

The simplest and most common form of artificial ventilation is found in kitchens and bathrooms, in the form of extractor fans.

Extraction in kitchens (from stoves and hobs) not only removes heat or steam and other vapour, but it also has the effect of removing grease that is in suspension, by filtration. Because the greasy air being removed is hot, the regulations state that extraction units must be manufactured from non-combustible material.

In bathrooms and toilets, extractor fans remove humid air and filter bad smells.

Air Requirements in Homes and Other Buildings

SANS 10400-O contains a useful table that shows the minimum requirements for air, per person using the room. Again it is the health and safety of inhabitants that is vital. Where rooms are used for smoking, a considerably higher supply of healthy air is required.