Voltage and current are inversely proportional to each other. In present time, the focus is more on keeping the level of voltage as high as possible. This will decrease the consumption of current. Both current and voltage are responsible for power factor. Either increase current and decreased voltage or decrease current and increase voltage for same power factor. Second method is always considered best. Now the main question that keeps on hovering in our mind is how to calculate voltage drop.

The main concern is of voltage drop across any wire. If certain precautions are not taken then there can be tremendous voltage drop between the source of power and the load. There can be several reasons that lead to drop in voltage. People use poor quality wire which is one of the main reasons behind this. This is known fact that every wire offers some resistance for current to flow. So certain amount of current is needed to overcome that resistance.

Now the main concern is how to calculate voltage drop. On increasing the length of wire, voltage drop can be mitigated to some extent. For a single phase calculation of voltage drop is done by knowing the values of current which is in ampere, resistivity which is in ohm, length which is in cm or metre, thickness of wire and resistivity constant for particular metal like for copper its value is 12 and for aluminium it is nearly 18. It is constant for specific metal.

The formula for voltage drop is VD=2*L*R*I/1000 feet. By putting the values of current, length, resistivity, thickness and resistivity constant, one can find the value of voltage drop across any wire. For a three phase supply, same formula works but multiplied the voltage drop by 0.866. Through this way one can easily know how to calculate voltage drop. In order to run small motors, current is prime important but when it comes to big machines or huge power consumption then voltage is utmost important. This is the main reason why step up and step down transformers are used. The current from power stations are sent via transmission wires through step up transformers. By knowing the exact value of voltage drop we can find out measures to mitigate it as much as possible.