What is Voltage Drop?
The term “Voltage Drop” is essentially refer to the reduction in voltage in an electrical circuit between the source of power to the end load where the source of power supply to.
How This Voltage Drop Happen?
By law of nature; Energy cannot be created and it also cannot be demolish. However, energy can be transform from one form of energy to another form of energy (ie: solar energy transform to electricity).
Cable will carry the electricity. The voltage drop in cable will happen by the time dissipation of heat by the cable itself by means of transforming of electrical energy to heat.
Why you need to calculate the voltage drop?
The main reason that you need to calculate the voltage drop is due to the IEE Wiring Regulation spelled that the voltage drop of cable should not be more that 4% between the main incoming supply points to the terminal of any fixed machine. So then, you have to calculate the voltage drop in order to meet this wiring regulation.
A significant drop in voltage could be the negative result of an incorrect conductor size in a cable.
How To Calculate The Voltage Drop?
Calculation of the voltage drop is given by the formula below
Where ; mV/Am = millivolt drop per meter per ampere of the cable
(this information is given in the table based on IEE Wiring Regulation)
I = Current in the cable (in Ampere)
l = Distance of cable (in Metre)
Example1
Based on IEE Wiring Regulation 16th Edition (Table 4D2B), the mV for 1X4C 50 sq mm Cu cable will be 0.81
Voltage Drop (Volt) = (0.81/1000) X 100 Amp X 100 metre = 8.1 Volt @ 1.95% of voltage drop.
Based on the calculation above, the percentage of the voltage drop is only 1.95% out of 4%. However, please take note that, the 4% is actually between the main incoming supply points to the terminal of any fixed machine. Therefore, the voltage drops from the Sub-Switch Board to the final connected load (ie. motors, lightings or socket outlets) need to be calculated as well to meet the wiring regulation.
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