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EFVA-Why this fires...1

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Why are there still all these fires?

Because the main phenomenon leading to these fires is not physically detected, including recent and "up to code" installations!


Changing theories concerning arcs and short-circuits.



In the industrialized countries worldwide, remains a non-negligible percentage of electrical fires, causing thousands of victims and the considerable destructions of goods every year.

This percentage remains abnormally elevated, considering that over decades the imposition of costly protections as well as the codes and the consequent controls.

At the same time, the real reason for these fires is never evoked: It is common to hear of short circuits or arcs, these are often technical aberrations:

An electrical fire is the result of a heating process which is not stopped or stopped too late; and that will have generated an auspicious atmosphere to the ignition of the fire. We all agree on this point.

Simple reminders to understand better:

The auspicious atmosphere igniting a fire is often created in a progressive manner by a heating-up that is going to transmit its energy to the environment, to damage and to carbonize the insulating material.

Often it will be too late:

If the auspicious atmosphere for ignition is created, and if the necessary conditions are present, a spark or heat alone will be able to start the fire in an unforeseeable manner.

The Joule effect is at the origin of nearly all electrical heating. If some current circulates, inevitably there is heat: All matter opposes a resistance to the passage of the current what produces the heat, it is the Joule effect. So the circuits of the houses carrying the current also undergo small heating, according to the resistance of the circuits, their cross-section surface area and of the quantity of current (Amperes) that is carried through them. The over-intensity (over-current) protections that are calculated according to these parameters are placed at the










departure of these circuits to limit the quantity of current and limit this heat. These are the fuses or the breakers, which are are very efficient protection devices.

Parallel arcs (Phase to Ground or Neutral to Ground) occur when some current leaves the normal circuit of the installation or a device. The Europeans call them "isolation faults". These phenomena can entail electric shocks to the users. Grounding is the first protective measure against these electric shocks.



It is the connection of all metallic masses through a protective conductor (PE or "ground"), bound to the Neutral in North America and to an independent ground (PE) in a large part of Europe.

The sought-after goal is the same: that the leaking current which travels through the metallic masses is channaled toward the ground to limit the electric shocks and to trigger either the protection devises for over-intensity (over-current) in North America or the differential device at the head of the installation (as a GFCI function integrated into the main breaker) for a big part of Europe. In the two cases, it is about having an automatic cut-off with the fault.

The risks of electric shocks are especially important as voltages rise. During the 1960's in France at the time of the increase of the voltage from 115 to the 230 volts the differential device integrated into the main breaker became obligatory. In North America to protect electric shocks, some very sensitive (5 milliamperes) GFCIs have been imposed at the downstream end of some circuits. But the circuits in themselves were not protected against the parallel arcs or isolation faults, as in a large part of the Europe.


" Parallel arc" between phase and Neutral is called in France and most of Europe "Short-Circuit".

See comparative diagram below:




*Except for the circuits protected by GFCI in the table or by AFCIs ( before 2008 ) (which both integrate a 30 mA differential device that protects from these parallel arcs or isolation faults capable of occurring in the circuit).


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