CRITERIA 2.2 – Fire prevention is explained in relation to industry safe practices and company specific

Causes of insulation fires:

• Mechanical damage occurs in high traffic areas through abrasion, conduit, cable contact with moving machinery, vibration, etc.
• Wiring should be led through tunnels and ducts.
• Extension leads are greatly at risk
• Temporary wiring and flexible extension lead.

Damage from the environment:

• Heat will break down PVC and rubber insulation Mineral
• Use cables resistant to heat e.g. insulated and fire-resistant cables
• Corrosive atmospheres may be damaged rubber and mineral insulated wiring
• In corrosive areas use PVC insulation
• Oil contamination damages rubber insulation
• Oil contamination should be avoided. PVC insulation resists damaged from most oils
• Moisture may damage mineral insulated wiring
• PVC insulation resists light moisture damage

Damage from overheating:

• Overloading, improperly made joints and lack of compatible suitable over current protection causes overheating
• Use correctly rated cables with over current protection
• Heat from welding operations near cables will damage insulation
• Protect cables, shield them from heat

Welding

• Welding near bunched cables is hazardous if there is waste in the area.

Lighting

• Most normal combustibles have an ignition temperature of approximately 180 °C. Some forms of lighting achieve temperatures above 200°C. Lighting therefore should be seen as a positive ignition source if combustibles are in close proximity to them.

Tungsten filament lamp

• Ventilated 200°C combustibles
• Keep well ventilated and keep clear of lighting or use guards
• Unventilated 600°C

Fluorescent lights

• Ballast’s on twin tube units allow for either parallel or series connection of the tubes.
• Where the unit has ballast connected in parallel, it is possible for one tube to be illuminated when the other has been removed or is flickering. If this continues, overheating and possible fire in the ballast may result.
• With series connected ballast’s current flow ceases as soon as one of the tubes shows either a fault or is removed. This type is preferred.
• Attend to faulty or flickering tubes promptly before they cause a problem in the ballast or starter.
• Position lighting units over aisle ways and open spaces, not over combustible goods.
• Install units which are inherently safe or have thermal protective devices.

Comfort Heating

• Most fires started by space heaters are due to carelessness and inadequate guarding rather than be electrical faults.

Radiant Heaters

• Secure into fixed position away from combustibles. Use guards around them to protect combustibles from being ignited. Ban portable radiant heater from the workplace.

Convection heaters

• Ensure good ventilation on fan-assisted, panel, or other types. These should be fitted with thermostatic safety switches, which will isolate power if they topple over. Indication lamps should be fitted to all convection heaters to show that the units are in operation.

Motors

• Most fires in electrical motors involve a short circuit in the windings, which heat wiring insulation to ignition temperature. Breakdown in winding insulation is usually caused by the following factors:
  • Ingress of dust, moisture, corrosives or excessive lubrication.
  • Vibration and misalignment causing rotors to touch casings or physically break down insulation.

Hazardous Atmospheres

• Areas where quantities of flammable vapours of dusts may be found represent a hazard
  through their possible ignition by standard electrical equipment. SABS 0108 – 1974 Code of Practice for the classification of hazardous locations and the selection of electrical apparatus for use in such locations describe suitable equipment for specified areas.

Transformers

• Transformers do not often fail but a fire can cause massive disruption and great financial loss.
• Transformers at or near maximum load should be regularly monitored and well maintained.
• Transformer fires may be prevented by:
• Early warning and protective equipment such as the Buchholz protective gear and fuse or over current breakers
• Checking oil regularly for moisture, contamination and quantity
• The use of non-flammable oils
• The use of dry transformers (up to 750 kVA)

The severity of transformer fires may be reduced by one or any combination of the following:

• Separating transformers from one another and valuable plant or structures by distance or fire-resistant walls to counter the effects of radiant heat.
• Bunding transformers to prevent the flow of burning oil to other transformers, plant or structures.
• Protecting with water spray or CO² systems for rapid extinguishment.

Main causes of fire:

Lack of awareness

• Where incorrect or improper installations, equipment or hazardous situations are seen but not recognized.

Carelessness

• Where existing or problem areas are recognizes but ignored

Lack of maintenance

• Where no problem areas are apparent, and it is felt that the cost of regular maintenance is not justified.

Blatant misuse

• Where unsuitable equipment is used or with a total disregard for safety regulations and practices.

Rules for Safety– On installation observe the following:

Suitable equipment

• Capable of performing the duties required should be installed. Unattended installations should have supervisory attendance and back-up protective equipment.

Special equipment for abnormal conditions

• Such as dusty, corrosive or moist environments and class 1 explosive areas

Qualified installers

• Especially with equipment for class 1 explosive area

Comply with regulations

• Such as statutory regulations and Institute of Electrical Engineers regulations

Care and maintenance– Follow these essential points:

• Care with portable equipment is essential, as it is inherently more subject to wear and tear.
• Regular testing
• Responsible people must check equipment regularly, before each work shift.
• Prompt attention to faults such as flickering fluorescent tubes, loose connections and faulty insulation
• Pre-planned maintenance

For all equipment and installations

• Switch–off – Ensure that all equipment, which is not in use, is switched off and where possible unplugged from the outlet. (Where wiring polarity has been reversed ground faults within the current carrying limits of protective gear can occur, leading to potential fires.).
• Post addition and alteration checks e.g. on polarity, are vital as faults frequently occur after installations have been disturbed.