What Is Voltage Drop?
Voltage Drop is the reduction in electrical pressure that occurs as current travels through a conductor, connection, or device. The reduction increases with circuit length, electrical load, and resistance. Excessive voltage drop can make lights dim, motors run poorly, or equipment fail to receive the voltage required for proper operation.
Quick Facts About Voltage Drop
Category
Electrical circuit condition
Used for
Troubleshooting power delivery
Common confusion
A voltage loss is not always a breaker trip
Also called
Voltage loss
Often discussed with
Electrical Troubleshooting
Key Takeaways About Voltage Drop
- Voltage Drop results from resistance in a circuit path.
- Longer runs and heavier loads usually create greater loss.
- Voltage Drop is not the same as a power outage.
How Voltage Drop Works
Voltage Drop occurs as electrical current moves through a circuit that has resistance. Wire, terminals, splices, and connected devices all contribute to the circuit path. The source may provide the expected voltage, while the equipment receives less because some electrical pressure is lost along the way.
Related glossary terms: Branch Circuit, Current, Electrical Load.
An electrician checks voltage at the source and at the load while the circuit operates. The difference helps identify whether wire size, distance, a loose connection, or the connected load contributes to the problem. A multimeter can show the voltage at each test point, while a branch circuit provides the complete path being assessed. Results guide troubleshooting of dim lights, weak motors, and equipment that starts unreliably.
From the San Bernardino Electrician team
When we investigate Voltage Drop, we measure the circuit under operating conditions and compare source voltage with load voltage. We inspect accessible connections, conductor condition, circuit length, and the equipment load. This approach helps separate a wiring problem from a device problem during Electrical Troubleshooting.
Voltage Drop in Practice: A Real-World Example
A customer reports that a garage light dims when a motorized tool starts. An electrician checks voltage at the panel and at the light while the tool runs, then traces the loss through the circuit path.
Related Services
Related Terms
Branch Circuit
A branch circuit is the portion of an electrical system that carries power from a panelboard…
Current
Current is the movement of electric charge through a conductor, such as a wire, circuit path…
Electrical Load
Electrical Load is the amount of electrical power a device, circuit, or building draws while operating…
Wire Gauge
Wire Gauge is a standardized way to describe a conductor’s thickness. The gauge identifies the wire’s…
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