Fire Archives » Building Regulations South Africa
Mar 052013
 

Regulations for Lightning Conductors on Thatch Roofs

Thatch house lightning Thatch Roofs and Lightning

Thatch roofs are most susceptible to be set alight by lightning than any other roof type. For the protection of the public and property the South African National Standard 62305-3 was introduced in 2011.

SANS 62305-3: Protection against Lightning (published in 2011) is drawn from an international standard, IEC 62305. Part 3 deals with “physical damage to structures and life hazard”.

Remember that anything related to electrics must be dealt with by a qualified and registered electrician.

Introduction to the Regulations for Thatch Roofs and Lightning

This part of IEC 62305 deals with the protection, in and around a structure, against physical damage and injury to living beings due to touch and step voltages.

The main and most effective measure for protection of thatch structures against physical damage is considered to be the lightning protection system (LPS). This usually consists of both external and internal lightning protection systems.

An external LPS is intended to:

  1. intercept a lightning flash to the structure (with an air-termination system),
  2. conduct the lightning current safely towards earth (using a down-conductor system),
  3. disperse the lightning current into the earth (using an earth-termination system).

An internal LPS prevents dangerous sparking within the structure using either equipotential bonding or a separation distance (and electrical insulation) between the external LPS components and other electrically conducting elements internal to the structure.

The main protection measures against injury to living beings due to touch and step voltages are intended to reduce the:

  1. dangerous current flowing through bodies by insulating exposed conductive parts, and/or by increasing the surface soil resistivity,
  2. occurrence of dangerous touch and step voltages by physical restrictions and/or warning notices.

The type and location of an LPS should be carefully considered in the initial design of a new structure, thereby enabling maximum advantage to be taken of the electrically conductive parts of the structure. By doing so, design and construction of an integrated installation is made easier, the overall aesthetic aspects can be improved, and the effectiveness of the LPS can be increased at minimum cost and effort.

Once construction work on a site has started, access to the ground and the proper use of foundation steelwork for the purpose of forming an effective earth-termination, may well be impossible. Therefore, soil resistivity and the nature of the earth should be considered at the earliest possible stage of a project. This information is fundamental to the design of an earth-termination system and may influence the foundation design work for the structure.

Regular consultation between LPS designers and installers, architects and builders is essential in order to achieve the best result at minimum cost.

If lightning protection is to be added to an existing structure, every effort should be made to ensure that it conforms to the principles of SANS 62305-3. The design of the type and location of an LPS should take into account the features of the existing structure.

Notations

NOTE 1

Specific requirements for an LPS in structures dangerous to their surroundings due to the risk of explosion are under consideration. Additional information is provided in Annex D for use in the interim.

NOTE 2

This part of IEC 62305 is not intended to provide protection against failures of electrical and electronic systems due to overvoltages. Specific requirements for such cases are provided in IEC 62305-4.

NOTE 3

Specific requirements for protection against lightning of wind turbines are reported in IEC 61400-24 [2].

References

The following referenced documents are indispensable for the application of this national standard. These references are listed in the standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

IEC 60079-10-1:2008, Explosive atmospheres – Part 10-1: Classification of areas – Explosive gas atmospheres

IEC 60079-10-2:2009, Explosive atmospheres – Part 10-2: Classification of areas – Combustible dust atmospheres

IEC 60079-14:2007, Explosive atmospheres – Part 14: Electrical installations design, selection and erection

IEC 61557-4, Electrical safety in low-voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. – Equipment for testing, measuring or monitoring of protective measures – Part 4: Resistance of earth connection and equipotential bonding

IEC 61643-1, Low-voltage surge protective devices – Part 1: Surge protective devices connected to low-voltage power distribution systems – Requirements and tests

IEC 61643-21, Low-voltage surge protective devices – Part 21: Surge protective devices connected to telecommunications and signalling networks – Performance requirements and testing methods

IEC 62305-1, Protection against lightning – Part 1: General principles IEC 62305-2, Protection against lightning – Part 2: Risk management

Nov 152011
 

National Building Regulations Part W – Fire Installation

Fire Installation 213 s Fire Installation

A typical fire installation in a factory showing the correct signage

Nov 152011
 

Chimneys, Flues, Hearths and Fireplaces
Used for Space Heating

FireplaceBR1 Space Heating

A freestanding fireplace with a flue that goes through ceiling

Anyone searching through the National Building Regulations for information about chimneys and flues, hearths and fireplaces, might go straight to the part that deals with Fire Protection. The next step would probably to look through the part that deals with Walls – after all chimneys are often built with bricks and mortar and often extend from a wall. Or Roofs might seem to be a good place to look.

But no, you are not going to find the information you are looking for in any of these three sections of the NBR. The information you need is in Part V of the Act. This section is very short, and deals only with the design, construction and installation of fireplaces and hearths that have chimneys and/or flues.

 

 

 

 

 

 

 

The legislation states:

“(1)  Any system of space heating in any building shall be so designed, constructed and installed as to operate safely and any flue, flue pipe or chimney used in such system shall be so designed as to safely remove any smoke or noxious gases produced by such system.

“(2)  The requirements of sub-regulation (1) shall be deemed to be satisfied where the design and construction of any flue pipe, chimney, hearth or fireplace complies with SANS 10400-V.” That’s it.

SANS 10400-V: Space Heating

As with all the Standards that make up SANS 10400, if you ensure that your installations comply with the SANS it will be “deemed to satisfy” the law. But other Standards are often cross-referenced. This Part of SANS 10400 makes reference to:

  • SANS 10177-5, Fire testing of materials, components and elements used in buildings –– Part 5: Non- combustibility at 750 °C of building materials.
  • SANS 10400-A, The application of the National Building Regulations –– Part A: General principles and requirements.
  • SANS 10400-B, The application of the National Building Regulations –– Part B: Structural design.

Like all the published SANS, it has a list of useful definitions, some of which you will find in our Glossary of Terms.

Examples include:

  • chimney That part of a building which forms part of a flue, but does not include a flue pipe
  • flue Passage which conveys the discharge of a heat-generating appliance to the external air
  • flue pipe Pipe forming a flue, but does not include a pipe built as a lining into a chimney

Hearth and fireplace are not defined!

Chimneys

Chimneys must be designed and erected from materials that are non-combustible – which of course stands to reason. It is also important that they don’t become a fire hazard, particularly to those materials adjacent to the chimney structure. Further, chimneys should not reinstalled in shafts or ducts that might be affected by heat.

Timber is one of the combustible materials that we commonly use in our homes, and the regulation states that elements including joists for timber floors, trimmers or roof trusses may not be built within 200 mm of the inside of any chimney.

There are additional regs that relate to dimensions, for instance where the walls of a brick or block chimney are less than 190 mm-thick, it must be lined with a flue lining that is made of a material that will withstand the action of any flue gases and won’t crack or soften. The flue lining must also extend throughout the full height of the chimney.

There are also regulations that relate to the height of the outlet – this has not changed since the regulations were published previously in 1990 (and of course you can download these free). Below you can see the chimney positions.

Part V opening or adjacent structure Space Heating

Opening or adjacent structure

Part V roff pitch 10 deg or more  Space Heating

Position when the roof pitch is 10 degrees or more

Part V Roof pitch less than 10 deg Space Heating

Roof pitch less than 10º

Flue Pipes

This is all largely common sense. Flue pipes may not be designed or installed if they are going to become a fire hazard to adjacent material. They may also not be connected to shafts or ducts that form part of any ventilation system. And they may not be installed in shafts or ducts that are likely to be adversely affected by heat.

Hearths and Fireplaces

Any fireplace that is used for burning “solid fuel” MUST have a hearth that is make of a non-combustible material that is sufficiently thick. It must extend no less than 500 mm in front of the grate or fire basket and not less than 300 mm beyond each side of the grate or fire basket.

Timber floor joists and trimmers – or any other combustible material – may be built into a hearth.

 

 

Nov 152011
 


What SANS 10400: Part T 
- Fire Protection Says

House fire x630 Fire Protection

Nobody wants to see their house or business premises go up in flames. This is why there are very strict Regulations when it comes to fire safety and protection against fire in any building in South Africa.

What the Act Says

Essentially the legislation is concerned quite simply with the need for all buildings to be designed, constructed and equipped so that in the event of fire:

  1. the occupants or people using the building will be protected – including persons with disabilities;
  2. the spread and intensity of any fire within buildings, and the spread of fire to any other buildings, will be minimized;
  3. sufficient stability will be retained to ensure that such building will not endanger any other building: provided that in the case of any multi-storey building no major failure of the structural system shall occur;
  4. the generation and spread of smoke will be minimized or controlled to the greatest extent reasonably practicable; and
  5. adequate means of access, and equipment for detecting, fighting, controlling and extinguishing such fire, is provided.

The requirements of the Act will be deemed to have been satisfied if the design, construction and equipment of buildings complies with SANS 10400 Part T and satisfies the local authority.

The Act also specifies several offences that owners of buildings need to avoid, including the need for fire extinguishers that comply with SANS 10105. Also, if people do anything to obstruct escape routes in buildings, they will be guilty of an offense.

What the Standard Says

The regulations for Fire Protection are contained in a 91 page document published by the SABS, SANS 10400: Part T Fire Protection. Much of the information is the same as that published in the 1990 version of the Standard that you can download from this site.

SANS 10400 Part T is broken down into several parts:

Requirements

The bulk of the Standard is made up of a vast number of different “requirements” that relate not only to dwelling houses, but to every other possible type of building, from hospitals to parking garages.

The requirements for effective fire protection include:

  • general requirements,
  • regulations relating to safety distances,
  • fire performance,
  • fire resistance of occupancy-separating and division-separating elements,
  • fire stability of structural elements or components,
  • tenancy-separating elements,
  • partition walls and partitions,
  • protection of openings (Note that the drawings in SANS 10400 – 1990 that illustrate this have not changed),
  • raised access and suspended floors of combustible material,
  • roof assemblies and coverings  (the drawings remain unchanged in the new version of the Standard) including thatch,
  • ceilings,
  • floor coverings,
  • internal finishes,
  • provision of escape routes,
  • exit doors,
  • feeder routes,
  • emergency routes,
  • dimensions of components of escape routes,
  • width of escape routes,
  • basements,
  • stairways and other changes of level along escape routes  (the drawing that shows the position of doors in relation to a change in level has not changed),
  • ventilation of stairways in an emergency route,
  • pressurization of emergency routes and components,
  • openings in floors,
  • external stairways and passages,
  • lobbies, foyers and vestibules,
  • marking and signposting,
  • provision of emergency lighting,
  • fire detection and alarm systems,
  • provision and maintenance of fire-fighting equipment, installations and fire protection systems,
  • water reticulation for fire-fighting purposes,
  • hose reels,
  • hydrants,
  • automatic sprinkler and other fixed extinguishing systems,
  • portable fire extinguishers,
  • mobile fire extinguishers,
  • fire-stopping of inaccessible concealed spaces,
  • protection in service shafts,
  • services in structural or separating elements,
  • smoke control,
  • air-conditioning systems and artificial ventilation systems,
  • lift shafts,
  • lifts,
  • firemen’s lift,
  • stretcher lift,
  • stage and backstage areas,
  • eating arrangements in auditoriums or halls and on grandstands,
  • parking garages,
  • operating theatres and intensive, high or critical care units,
  • installation of liquid fuel dispensing pumps and tanks,
  • installation of other tanks,
  • warehousing of dangerous goods,
  • dangerous goods signage,
  • access for fire-fighting and rescue purposes,
  • resumed fire resistance of building materials and components,
  • building materials,
  • guest houses and bed and breakfast accommodation (this is completely new),
  • health care facilities (this is also completely new).

Safety Distances

Although there are other provisions, including the classification of the type of external wall, the table below may be used to establish safety distances where walls do not contain windows or other openings. For ordinary “dwelling houses” where the area of elevation facing any boundary is not more than 7,5 m2, such safety distance may be reduced to 0,5 m.

Part T safety distances1 Fire Protection

Part T safety distances2 Fire Protection

Fire Resistance

There are several tables (five in all) that indicate requirements for compliance with “Presumed fire resistance of building materials and components”.

This table shows what is required for “structural walls”.Part T Fire resistance of structural walls Fire Protection

This table shows what is required for “non-structural walls and partitions”.Part T Fire resistance of non structural walls and partitions Fire Protection

Rational Designs

The design requirements include the need for a competent person to ensure that the level of fire safety is adequate. This is particularly important in large and public buildings.

This drawing shows the basic fire safety engineering process.Part T Basic fire safety engineering process Fire Protection