UNDERSTANDING ELECTRICAL CAUSES OF FIRE

Introduction

Identifying the nature of fire is crucial to understand the potential cause. A fire needs the proper proportions of oxygen, fuel and source of heat to burn. Careless disposal of smoking materials and electrical apparatus faults are often given as the cause of many fires in the absence of further proof.

With few exceptions, fires of electrical origin occur due to lack of reasonable care in the maintenance or use of electrical installations and apparatus.
The energy that provides heat and light and drives electric motors is also capable of causing fire.
A fire of electrical origin may be initiated by any one of the conditions summarised below:
• General overheating
• Local overheating
• Tracking
• Arcing and sparking
• Ventilation failure
• Electrostatic discharge

Evaluating electricity as a cause of fire

The electrical evaluation is very much like the fire scene examination itself, and both require a systematic, step-by-step approach to uncovering evidence. In a fire of suspected electrical origin, fire investigators should remember to:

• Begin the electrical system examination at the service panel

• Note the size and conditions of the over-current protective devices (i.e. fuses, circuit-breakers, etc.)

• Photograph, then secure, tripped, blown, damaged or bypassed protectors as evidence and make a record of what circuits were served by these protectors

• Examine intact protectors for proper installation or signs of tampering

• Evaluate wiring to make sure it is adequately sized to safely carry its designated current load

• Trace wiring from the service panel to the area of suspected fire origin using - if needed - electrical drawings or other sources of wiring information

• Note the physical condition of the circuits - look for such hazards as unboxed connections, mis-matched connections, worn switches, loose connections and uncovered junction boxes

• Examine all subsidiary fuse and circuit-breaker boxes

• Establish, if possible, whether appliances and other electrical equipment were connected to appropriately rated circuits

• Pay special attention to any breaks in wiring

• Evaluate pointed, splattered, beaded and ragged ends in wiring that may be caused by overloading, shorting or external fire damage

• Were there any appliances or circuits in the area of origin ?

• Examine insulation for additional information about the fate of the wire, including:

1. A rich source of electrical information at the fire scene is damaged wiring. Often, analysis of broken wiring can tell the investigator how the fire began.

2. Arson investigators should know that short-circuits can cause fire and that fires can cause short-circuits. Borken wires usually result either from a short-circuit or from the wire being caught in an exceptionally hot part of the fire. Simple overloads rarely cause a wire to break. The tips of broken wires usually tell the story of how the break occurred.

3. If the wire was innocently caught in a hot spot, the tips of the wire will generally be smooth and pointed.

4. For example, copper wire melts at nearly 1100?C, and aluminium melts at around 650?C. Once the metal softens, it gives way under its own weight.

5. The resulting break looks like modelling clay or toffee when it is pulled. The wire is stretched and progressively narrowed until, finally, it separates.

6. In contrast, the direct short-circuit break displays two effects. The first is splattering in which the metal splatters and deposits back on the wire, because the magnetic field produced by the current surge pulls little bits of metal off the wire. When the field collapses, some of the pieces are driven back. This same phenomenon occurs when a fuse succumbs to a short-circuit.

7. The second effect in a shortened wire is the formation of a bead at the tip. As the wire melts in the heat of a short, surface tension in the liquid pool of metal draws it into a bead. The process is similar to the formation of a droplet at the tip of a melting icicle.

8. Defective connections, accumulations of metal filings in machinery, and damaged insulation, are among the many conditions which cause short-circuits.

9. Not all hot wires bead or splatter, however. Wires that were heated from an overload, for example, sometimes show only partial shorting damage.

10. In these cases, the insulation covering the wires gradually degrades. The degraded insulation allows two wires of opposite current flow to brush each other, causing an intermittent short-circuit. Such damage is generally less pronounced than that which results from a direct short.

11. These intermittent short-circuits between the two conductors are usually at such high resistance that the over-current protective device may not be tripped or blown.

12. The metal splattering seen in such an intermittent short resembles the aftermath of a direct short, only it will be less extensive. The wire may not even be broken.

13. Finally, the ends of some broken wires are neither pointed, splattered nor beaded.
They are merely ragged.

14. Such wires probably become brittle in the heat of the fire and break under some mechanical stress applied at that time. This stress may have been caused by jarring or jostling that occurred in the course of fighting the fire, or from structural collapse.

15. If these wires were carrying current at the time they broke, some pitting of the ends may be caused by arcing.

16. Sometimes, the remains of the insulation on a wire will give additional clues as to the fate of the wire.

17. The two most important patterns of insulation damage are called "sleeving" and "adhering". One indicates that the wire was heated from the inside and the other indicates that the heat source was external.

18. In sleeving, the inner part of the insulation (i.e. the part closest to the wire), heats faster than the outer coverings. The insulation pulls loose from the wire and hangs out from it.

19. In adhering, the insulation is uniformly destroyed by heat all around the outside of the wire. Burned patches stick to the metal underneath.

20. Because the heat source is the wire itself, many experts believe that sleeving is a reliable indicator of an overloaded wire.

21. Other experts point out that metal conducts heat as well as electricity. If one end of the wire is heated, sleeving could occur as the high temperatures make their way down the metal path. In the light of these facts, the condition of the insulation is not definitive by itself. On the other hand, the presence of sleeving can corroborate other indications of an overload.

22. These include the conditions of fuse and breaker elements, and the use of high energy appliances at the time of the fire.

23. One final point about wiring is that the presence of electrical conduits in the fire area sometimes can reveal the source of the fire. Since the conduit represents a fixed barrier between the wiring inside and the fire outside, it is usually fairly simple to distinguish damage caused by external heat. An internal heat source would leave most severe burn patterns on the inside of the conduit.

When complex electrical systems are located in the suspected area of fire origin, and because of the specialised nature of an electrical examination, investigators may seek the professional assistance of a trained electrical expert. This expert may work with the investigation team to uncover evidence already found by the investigators. The testimony of such an expert witness may prove valuable in Court.

The information is supplied by http://www.cunninghamlindsey.com

THE SPECIAL EFFECTS OF CATASTROPHE ON BUSINESS AND THE APPLICATION OF INSURANCE COVERS

WHAT IS A CATASTROPHE?

If an individual business suffers a fire, which destroys all of its buildings, plant and stock, the proprietors of that business would probably describe the event as a catastrophe. There is no doubt that events can affect individual business in isolation in ways, which are catastrophic to those businesses. However, in this paper, we are looking at a different concept of catastrophe.
What we are considering is a situation where major damage affects not just an individual business but a whole area for example in Thailand Flooding. In other words, we are defining catastrophe in this context as major damage affecting many businesses and individuals at the same time.

SPECIAL EFFECTS OF CATASTROPHE

When an individual business suffers damage in isolation, it can rely on a number of constants outside the business. For example, emergency services such as the Fire Brigade will be there to respond quickly. Contractors will be available to repair the damage and facilities are available in the surrounding economy to assist the business to re-establish itself.
In a catastrophe, the situation is much more dynamic. What are constants when an individual business suffers damage in isolation are no longer necessarily constant.

There is no doubt that businesses are faced with greater challenges in a catastrophe. A number of these are discussed shortly.

THE APPLICATION OF INSURANCE COVERS

Insurance covers are often designed with a focus on possible effects of damage, which is isolated to an individual business. Covers, which may well have been adequate in normal situations, can prove inadequate when a catastrophe occurs. Some of the problem areas will emerge in the discussion, which follows.

THE IMMEDIATE RESPONSE

When a catastrophe strikes, the common reaction is one of confusion. Communications are affected, and emergency services were difficult to co-ordinate and direct to the highest priorities. Available resources will be stretched to the limit.

Buildings, which suffer major damage, need emergency repairs to make them safe. Resources to carry out those emergency repairs can be stretched to the limit. This can lead in some cases to significant delays. In some cases, to attempted profiteering by unscrupulous repairers who attempt to take advantage of the excessive demand for their services.

Those businesses, which do have contingency plans sometimes, assume that the surrounding infrastructure will be in place. However, this assumption is not valid in a catastrophe situation.

ACCESS PROBLEMS

With the general damage caused in a catastrophe, there are access problems throughout the affected area.

This causes businesses a number of problems. In some cases, they have difficulty protecting and salvaging property as well as carrying out temporary repairs. It also means that businesses are interrupted while access was hindered.

These businesses required properly worded "Property in the Vicinity" extensions to their Business Interruption policies. The significance of these is discussed a little later.

DELAYS IN RE-INSTATEMENT

In a catastrophe, it can take much longer than expected to repair or replace damaged property. We spoke earlier about the difficulties in carrying out temporary repairs with resources stretched to the limit. The heavy demand on available resources also means that permanent repairs or re-instatement can take much longer than they would in the event of isolated damage.
In some catastrophes, it may be inadvisable to commence repairs straight away. The full extent of the damage is not immediately apparent in many cases.

This has a particular significance to the length of the Indemnity Periods in Business Interruption policies. In a number of cases, businesses found that the Indemnity Periods can expire before they are able to commence repairs. In a lot of these cases, the real interruption to the businesses had not yet taken place: they had been able to continue trading from buildings which had some cracks but they would have to stop trading while the repairs were carried out.

In a situation such as this, there is sometimes pressure on Insurers to delay the start of the Indemnity Period so that it encompasses the period during which the business is actually disrupted. However, the definition of Indemnity Period, which is almost universal, provides that it starts running from the date of the damage and Insurers would have to go outside the terms of the contract in order to delay its commencement. A catastrophe situation will usually require a longer Indemnity Period and this must be considered when the scope of the cover is being formulated.

THE TRADING EFFECTS OF CATASTROPHE

There are a number of ways in which a catastrophe can affect the trading results of a business. Firstly and most obviously, a business can be affected by damage to its own property, as it would be in the event of isolated damage. However, the damage, which is caused to other properties in the event of a catastrophe, may have an even bigger impact on the business.We spoke earlier about the access problem. Damage to property in the vicinity of the business can affect its ability to trade. So can damage to public utilities such as electricity suppliers. Damage to suppliers of goods can affect the business as can damage to customers.
Beyond this, there are more general effects, which can impact the business. These include the economic and psychological effects of the catastrophe which can both severely alter spending patterns.

Many of these effects are not covered by standard Business Interruption policies. While many policies have some extensions, which go part of the way to covering some of these effects, it is still uncommon to find a policy, which would cover all of them.
To explain this, it is necessary to review just what a basic Business Interruption wording covers. It refers to a specific sequence:
1. An insured peril (e.g. flood);
2. Damage by the insured peril to property used by the Insured at the premises (the premises are specified in the policy schedule);
3. Business Interruption resulting from that damage.

In other words, the policy does not simply cover all the trading losses resulting from an insured peril (such as a flood). It covers losses resulting from flood damage to specific property. More particularly, it covers losses resulting from damage to property used by the Insured at the premises.

Unless the wording contains appropriate extensions, losses resulting from damage to other property are cover for trading losses caused by a catastrophe.

CONCLUSION

A catastrophe can affect businesses in ways which isolated damage does not. Many insurance policies are taken out and limits of liability set with a focus on the effects of isolated damage. However, the dynamics of a catastrophe have to be considered when deciding the cover, which is needed.