This document discusses fire behavior and its causes. It describes thermal balance as normal fire movement and thermal imbalance as abnormal movement caused by interference that can confuse origin determination. It also defines dangerous fire behaviors like backdraft and flashover. The causes of fire are divided into natural, accidental, and intentional categories. Natural causes include spontaneous heating, lightning, and solar radiation. Accidental causes involve electrical issues such as short circuits, arcing, and appliance overheating. Intentional fires are characterized by the use of accelerants, materials planted to start the fire, and substances spread to promote burning.

1. FIRE BEHAVIOR

2. 1. THERMAL BALANCE – the rising movement pattern
of fire, which is deemed to be normal behavior when
the fire is undisturbed.
2. THERMAL IMBALANCE - the abnormal movement
of fire due to an interference of foreign matter,
thermal balance often confuses the fire investigation
in determining the exact point where fire
originated.(causes confusion in fire investigation)

3. DANGEROUS / FATAL
BEHAVIOR OF FIRE

4. 1. Back Draft – is the sudden and rapid
(violent) burning of heated gasses in a
confined area that occurs in the form of
explosion (Smoke Driven)
2. Flash Over – is the sudden ignition of
accumulated radical gasses produced
when there is incomplete combustion of
fuels. (Heat Driven

5. CAUSES OF FIRE
1. NATURAL CAUSES
2. ACCIDENTAL CAUSES
3. INTENTIONAL CAUSES

6. A. NATURAL CAUSES
1. Spontaneous Heating – automatic
chemical reaction the results to
spontaneous combustion due to auto
ignition of organic materials the gradual
rising of heat in confined space until
ignition temperature are reached.

7. 2. Lighting – a form of static electricity a natural
electric current with great magnitude producing
tremendous amperage and voltage.
• Holt Bolt- longer in duration capable only is igniting
combustible materials.
• Cold Bolt- shorter is duration, capable of splintering
a property of literally blowing a part an entire
structure produced electrical amperage and very
high temperature.
3. Radiation of sunlight – when a light lies a concave
mirror, concentrating the light on combustible
materials thereby ignites.

8. B. ACCIDENTAL CAUSES
Electrical accidents
1. Short circuit –unusual or accidental connecting
between points at different potentials (charge) an
electrical circuit of relatively low resistance.

9. 2. Arcing – production of sustained luminous
electrical discharge between separated
electrodes an electric hazard that result when
electrical current crosses the gap between two
electrical conductors.
3. Sparkling – production of incandescent
particles when different potential (charged
conductors) come in contact occurs during the
short circuit or welding operations.

10. 4. Induced current – included line surge increase of electrical
energy flow or power voltage induced current sudden increase
of electrical resulting to the burning of isolating materials
exploding of the fuse box or burning of active electric
appliances
5. Overheating of electrical appliances – increase or rising of
amperage while electric current is flowing in a transmission line
resulting to the damage or destruction of insulating materials
may be gradual or rapid internal or external.

11. C. INTENTIONAL CAUSES
If the burned property, there are preparations or
traces accelerated and plants and trailer then
the cause of fire are intentional.

12. 1. Accelerant – highly flammable chemical
that are used to facilitate flame propagation.
(Speed up)
2. Plant – the preparation and/ or gathering
of combustible materials needed to starts a
fire. (Starter)
3. Trailer – the preparation of flammable
substances in order to spread fire. (Spreader)