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 results from resistance in the circuit. A load may receive less voltage than the source provides, which can affect equipment operation, lighting performance, and troubleshooting results.
Quick Facts About Voltage Drop
Category
Electrical measurement
Used for
Circuit troubleshooting
Common confusion
Confused with low supply voltage
Also called
Voltage Loss
Often discussed with
Electrical Troubleshooting
Key Takeaways About Voltage Drop
- Voltage Drop occurs across resistance in a circuit.
- Longer runs and poor connections can increase the loss.
- Voltage Drop is not the same as a short circuit.
How Voltage Drop Works
Voltage Drop occurs as electrical current moves through resistance in a circuit. Wire, terminals, switches, and other connections all have some resistance. The voltage at the load can therefore be lower than the voltage measured at the source.
Related glossary terms: Branch Circuit, Electrical Load, Electrical Meter.
An electrician checks Voltage Drop by measuring voltage at useful points while the circuit operates under load. Comparing the source reading with the load reading helps show where electrical pressure is being lost. A long conductor run, an undersized wire, a loose terminal, or corrosion can contribute to the loss.
Electrical Load behavior can help identify the problem. Lights may dim when equipment starts, or a motor may struggle to operate. Testing each section of the circuit helps separate a wiring issue from a problem inside the connected equipment.
From the Chris Miller Electric team
When we troubleshoot Voltage Drop, we measure the circuit at the source and at the operating load. Our team then checks connections, conductor condition, and the path between those points. We also compare readings under different load conditions because a circuit can appear normal when no equipment is running.
Voltage Drop in Practice: A Real-World Example
A homeowner notices that a light becomes dim when a nearby motor starts. During Electrical Troubleshooting, the electrician measures the circuit while both devices operate and checks connections along the branch circuit for a significant loss.
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Related Terms
Branch Circuit
A Branch Circuit is a wiring path that carries electricity from a service panel to outlets…
Electrical Load
Electrical load is the amount of power that connected equipment draws from an electrical system at…
Electrical Meter
An electrical meter is a testing instrument that measures electrical values in a circuit, such as…
Line Voltage
Line Voltage is the electrical potential supplied by a building’s wiring system to operate equipment and…
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