Line voltage differences have a significant impact on the occurrences of electrical fires and is due to the fact that in 100V-127V electrical systems, the electrical current is twice the electrical current of a 220V-240V system that supplies the same electrical power.
As the voltage in the 100V to 127V is about half the voltage in the 220V to 240V systems, the electrical currents in the 100V to 127V systems should be doubled in order to supply the same Power ( P ) to each load.
Many electrical faults are caused by temperature rise over a resistive-point in the electrical wiring of the circuit. This resistance is formed, many times, by corrosion, micro-arcing and loose connections. We call it “Parasitic Resistance”.
Now let us have a look at the voltage across that parasitic resistance. The voltage across the parasitic resistance of an electrical circuit is sometimes referred to as “I2R losses”. The term “losses” is used because the voltage across that parasitic-resistance causes the voltage that reaches the electrical load to be lower ( and therefore less effective ) than the voltage that entered the electrical system.
When comparing I2R losses in 100V to 127V systems against I2R losses in the 220V to 240V systems, we can see that as I ( the electrical current ) in the 100V to 127V systems is double than I in the 220V to 240V systems – I2 is 4 times larger.
This means that the value of R that will generate a specific I2R loss in a 100V to 127V system will be 1 / 4 of the R in a 220V to 240V system with the same I2R loss.
In cases where the R of the I2R loss is a resistive point that develops due to aging of the electrical wiring, this means that in 100V to 127V systems the resistive point reaches a fire ignition point in a significantly shorter aging time.
More information about the effects of line voltage levels on the occurrence of electrical fires is on the white paper available to download below.