Introduction to Fire Safety Management

Causes and prevention of fi re
137
heats up and melts the insulation and can set fi re to 
fl ammable material nearby. Commonly found in fl exible 
cables or cords, or consumer panel/power board leads. 
Over recent years there have also been a number of fi res 
involving electrical extension leads, where the cable 
has remained fully wound on the cable drum. The fl ow 
of electricity and the tightness of the fully wound cable 
prevent heat dissipation causing overheating and a fi re 
to start.
Loose wiring connections
– the current fl owing through 
the wiring encounters resistance at the connection and 
generates heat. This can start a fi re in the wall at the 
back of a power point or socket, in a wiring junction box 
in the ceiling, above light fi ttings or inside a switch/fuse 
board or consumer panel.
Electrical ‘arcing’ (or sparking)
– this generally occurs 
where wiring insulation has been damaged by an exter-
nal occurrence perhaps due to poor location (e.g. under 
fl 
oor coverings). This deterioration to the insulation 
allows the copper conductors inside the cable to touch 
one another briefl y, or to just make contact with the 
metal case of an appliance.
A small current will then fl ow from the ‘live’ con-
ductor to the neutral or earth wire, or to the earthed 
metal case. The current will initially be too small to 
blow a fuse or to trip a circuit breaker, but because the 
contact area is also very small (a few strands of wire) the 
heat produced at this point can reach suffi ciently high 
temperatures to melt or vaporise metals such as copper, 
brass or sheet metal. The localised heating or energy 
release will ignite combustible materials in close proxim-
ity and start a fi re.
The above-mentioned arcing faults are ‘uncontrolled’ 
whereas arc welding makes use of this energy release 
and is an example of ‘controlled’ arcing, which will be 
discussed later in this chapter in fi re hazards during 
construction and maintenance work.
Poorly maintained equipment, unauthorised use 
or maintenance of electrical systems, components and 
equipment, lack of formal and informal checks and 
inspections can all be directly linked to causes of fi res 
within the workplace.
Fires have been known to have been caused by 
vermin such as rats eating through electrical cables 
within basement areas due to a lack of vermin control 
procedures.