How to Troubleshoot Unexpected Voltage Drops in Your Business’s Electrical System

How to Troubleshoot Unexpected Voltage Drops in Your Business's Electrical System


Unexpected voltage drops can cause major disruptions to your business. When the voltage in your electrical system drops, equipment starts malfunctioning, lights flicker, and devices turn off unexpectedly. As a business owner, it's crucial to understand common causes of voltage drops and learn how to systematically troubleshoot them. This guide will provide an in-depth overview of troubleshooting unexpected voltage drops in your business's electrical system.

Common Causes of Voltage Drops

There are several potential root causes of unexpected voltage drops in a commercial electrical system:

Overloaded Circuits

The most common cause of voltage drops is overloaded circuits. When too many devices and equipment are drawing power from the same circuit, it can overload the circuit and cause the voltage to drop or fluctuate. Common signs of an overloaded circuit are frequent tripping of circuit breakers, flickering lights, and devices randomly turning off.

Faulty Wiring

Faulty wiring like loose connections, corroded wires, and undersized cables can cause unexpected voltage drops in your system. These wiring faults increase resistance to electrical flow, resulting in voltage drops. Faulty wiring often leads to overheating of wires and insulation damage.

Problems with Transformers

Transformers are used to step-down high voltage from the utility to lower voltages for use in your electrical system. Issues with transformers like short circuits, open windings, and poor connections can lead to inefficient power transfer and voltage drops.

Failures in Power Distribution System

Problems in the main power distribution system like loose service connections, undersized service cables, and excessive lengths of feeders can also cause voltage drops in your business. Issues in distribution equipment like breakers, lugs, and busbars can also be responsible.

Large Fluctuations in Power Demand

Sudden large power demands from heavy equipment like HVAC systems and industrial motors can cause temporary dips in voltage. The voltage drop may persist until the equipment switches off again.

How to Troubleshoot Voltage Drops

When faced with unexplained voltage drops in your business's electrical system, follow these troubleshooting steps:

1. Check the Utility Voltage

First, check the incoming voltage from the utility line using a true RMS multimeter. This will determine if the voltage drop is originating before or after the main electrical panel. Attach the multimeter leads to hot and neutral terminals and take a voltage reading. The incoming voltage should be around 120 volts for small commercial buildings. A significantly lower reading indicates an issue with the utility service and transformer.

2. Inspect the Main Service Panel

Open the main service panel and inspect the following:

3. Check Individual Circuit Breakers

With the panel open, systematically switch each circuit breaker off and on, and listen for any audible clicks. Breakers that don't make a distinct clicking sound need replacement. Also check for any tripped breakers which may indicate an overloaded circuit.

4. Inspect Connections and Wiring

Thoroughly inspect the wiring throughout your electrical system:

5. Test Voltage Under Load

Using your multimeter, test voltage at multiple outlets throughout the building while operating connected equipment. Observe if the voltage dips significantly below 120 volts, which indicates wiring issues between the panel and outlets.

6. Isolate Overloaded Circuits

If voltage at the panel is normal but drops under load, it likely indicates an overloaded circuit. Isolate each circuit by turning off breakers one by one until you identify the problem circuit showing lowered voltage. You may need to rearrange equipment across circuits to balance loads.

7. Contact an Electrician

For any complex voltage drop issues, contact a licensed electrician to thoroughly inspect your power distribution, wiring, and equipment. They have the necessary tools and expertise to diagnose and fix the problem.

Preventing Voltage Drops

Here are some tips to prevent unexpected voltage drops in your electrical system:


Voltage drops can disrupt business operations and damage sensitive equipment. By methodically troubleshooting the electrical system and addressing root causes like overloaded circuits and faulty wiring, you can restore proper voltage levels. Preventive maintenance and upgrading outdated systems is key to avoiding recurring issues. Seek help from licensed electricians for optimal results.