Abdullah Shoaib
Managing Director
5 min read
Last Updated June 13, 2025
What is voltage drop?
Voltage drop is a key concept in electrical systems that affects both safety and performance – and as such, it can have a big impact on your business operations if left unchecked. Understanding what voltage drop means is the first step to knowing if it affects you and, if needed, finding a solution that protects your business from feeling the effects of this supply problem.
In this article, we define voltage drop and identify a range of possible causes. Keep reading to learn more.
What is a voltage drop?
When electricity moves through wires or cables, it encounters resistance. Just like water flowing through a narrow pipe slows down, electrical current loses some of its energy as it pushes through wires. This lost energy results in a lower voltage being delivered at the end of the circuit than at the start – and that’s called voltage drop.
kVA measures apparent power in an electrical system, made up of reactive power (lost to inefficiencies) and real power (used to perform work). It reflects the total power supplied by a source, and the unit is commonly used to size generators and transformers. Match your power needs to the right sized transformer or generator, and your system will run more efficiently.
If you experience too much voltage drop, your equipment may not work properly. Lights may flicker or dim, motors can run too hot and sensitive electronics may fail prematurely. In extreme cases, it can even create fire hazards.
For businesses, voltage drop can mean increased maintenance costs, reduced equipment lifespan and lower productivity. It can be especially impactful in commercial environments with long cable runs, heavy machinery or large premises.
What causes voltage drop?
As mentioned, voltage drop is caused by the natural resistance that an electrical current encounters as it flows through a conductor like a wire or cable. It can be exacerbated by a range of factors, including:
- The distance the electricity has to travel
- The size of the conductor
- The level of resistance applied to the current
- Damage to the components of the electrical circuit
- Poor quality materials.
Let’s take a more in depth look at how that works.
Cable length
The further electricity has to travel from the power source to the equipment, the more opportunity there is for voltage to drop. This is especially relevant in larger commercial buildings, warehouses or outdoor installations, where the electrical current has to travel a long distance by necessity.
Cable diameter
Thinner cables offer more resistance than thicker ones, so if a wire isn’t properly sized for the current it’s carrying, voltage drop will be more severe. Think of it like a water pipe – the wider the pipe, the more water can flow through it at a time. Choosing the right cable gauge for the job at hand can help to limit this factor.
Current load
Current load – how much electricity is being drawn through the circuit – is another factor. The higher the current demand, the more resistance the cable presents and the greater the voltage drop. Equipment that draws large amounts of power, such as machinery or HVAC units, can quickly increase voltage drop if the system isn’t designed to handle it.
Faults in the system
Poor connections or corroded terminals can also contribute to voltage drop by increasing resistance at connection points. Over time, loose or damaged wiring can worsen this problem. This is part of the reason why it’s important to have components replaced and checked regularly.
Low quality materials
Not all cables and conductors are made the same, and choosing the right materials can be just as important as picking the right cable gauge. For example, copper wiring offers less resistance than aluminium wire, so it may be the better choice for systems that are prone to voltage drop.
All electrical systems are affected by voltage drop, but if your business electricity is suffering the effects as a result, it might be time to see what you can do to optimise your equipment. Minimising voltage drop ensures that the electricity you’re paying for powers your equipment more efficiently – a positive for all.