Home Improvement

Voltage Drop Explained

Due to potential safety issues, it’s critical to calculate voltage drop for lengthy chord assemblies (longer than 15 m). Among the causes are safety concerns, potential cord and wire damage, and device power loss.

That’s why it’s important to know how to use a voltage drop wire calculator, but what is voltage drop?

image - Voltage Drop Explained
Voltage Drop Explained

What Is Voltage Drop?

Charges accumulate at one end of an electric conductor or device due to its resistance, which causes a voltage drop. The resistance of the gadget delays the flow of charges through it, changing the voltage between its two locations.

The voltage is reduced from 20 volts to 16 volts, for instance, if an electrical device has a voltage of 20 volts at point A (where charges enter the device) and a voltage of 16 volts at point B (where charges escape the device). In this instance, there was a 4-volt voltage decrease.

Any electric conductor has resistance, which is important to keep in mind in order to comprehend what the voltage drop is.

By resisting electric current, an electric element lowers the voltage and alters the number of charges on both sides. To get a higher voltage drop, the element’s resistance must be raised.


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Electric wires are a part of every electric circuit. The formula R =ρ L /A states that the resistance of a wire (R) is dependent on its length (L), cross-sectional area (A), and material resistivity constant (ρ).

The resistance of the wire is inversely related to the cross-sectional area but directly proportional to its length.

The resistance of the wire is inversely related to the cross-sectional area but directly proportional to its length. The cross-sectional area of the wire and its diameter, or wire gauge, are related. Larger cross-sections of thicker wires (lower gauge values) result in reduced resistance.

Higher gauge numbers for thinner wires have smaller cross sections, which increases resistance. The voltage drop across gauge 40 wire is greater than that across gauge 1 wire because the skinny gauge 40 wire has a higher resistance than the thick gauge 1 wire.

If the circuit required higher voltage drops, an electrician would select higher wire gauges.

A Circuit’s Voltage Drop

Think about a voltage drop circuit that consists of a series connection of a battery, a resistor, and a lightbulb. At every point in the circuit, the power source’s (battery’s) electric current is constant.

A change in the number of charges between the two ends (A) and (B) of the bulb results from the electric current passing through one end (A) of the bulb and encountering its internal resistance before exiting the other end (B).

The difference in the number of charges between the bulb’s two ends determines the voltage drop across the bulb. In this circuit, there are two voltage drops: the first is across the bulb, and the second is caused by the resistor.

Voltage drop calculations are necessary while designing a building’s or home’s electrical wiring system. The electricians design electrical circuits to guarantee that power is available at every outlet and switch box in every room.

Any connected appliance in the home, such as a fridge or HVAC system, is built to take power in order to operate satisfactorily at a source of generally consistent voltage.

In other words, the voltage in the house’s circuit dips when the refrigerator’s motor starts, but the continuous supply immediately makes up for it.

Imagine a power outage affecting 5,000 homes with 5,000 HVAC systems, 5,000 refrigerators, and several other electronic gadgets that will all turn on simultaneously when the power is restored.

A voltage drop may occur at each home if the power supply is unable to compensate for the high demand simultaneously.

An item that is built to consume a specific amount of energy every hour, such as an HVAC unit, must get this energy from the power source in order to work.

An appliance with an electric motor will struggle to start if the voltage falls too low, which will result in a burned-out or damaged circuit on the circuit board of the appliance.

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Published by
Perla Irish