How to Test a Circuit Breaker Using a Digital Multimeter

How to Test a Circuit Breaker Using a Digital Multimeter

May 27, 2024

The digital multimeter is an electrician’s best friend, but it’s also incredibly useful for homeowners and business owners who want to tackle basic electrical troubleshooting. One common issue that arises is a malfunctioning circuit breaker.

Knowing how to test a circuit breaker using a digital multimeter can save time and money, and it can ensure your electrical system’s safety. In this brief article brought to you by Mr. Electric, we walk you through the process step-by-step.

This guide should help even if you have little to no experience with electrical work, but it is always advisable to hire a certified electrician if there are serious safety risks. Scorch marks, sparking, and burning smells are all RED FLAGS! Call Mr. Electric if you need urgent circuit breaker repair.

About the Circuit Breaker

A circuit breaker is a safety device designed to protect an electrical circuit from damage caused by overcurrent or short circuit. It automatically interrupts the flow of electricity if it detects a fault, thereby preventing potential hazards such as electrical fires.

However, circuit breakers themselves can sometimes fail, and testing them with a digital multimeter is a straightforward way to diagnose the problem.

First Thing’s First…

Before starting, ensure you have the following tools and safety measures in place:

  1. Insulated gloves to protect against electric shock.
  2. A flashlight if the electrical panel is in a dark or dimly-lit area.
  3. A screwdriver to access the circuit breaker panel.
  4. The digital multimeter, which will measure the electrical properties such as voltage, current, and resistance.

Always take safety precautions seriously. If you feel unsure or uncomfortable working with electrical components, consult a certified electrician. To have a uniformed electrician handle the electrical repair service, call Mr. Electric.

The Steps to Testing a Circuit Breaker

  1. Before testing the breaker, wear your insulated gloves and make sure all connected appliances and devices are turned off to prevent any electrical surge.
  2. Locate the circuit breaker panel. It is typically found in basements, utility rooms, or garages.
  3. Use a screwdriver to remove the screws securing the panel cover. This will expose the circuit breakers.
  4. Identify the affected circuit breaker. Usually, a faulty breaker will be in the "off" position or stuck between the "on" and "off" positions.
  5. Turn on the multimeter and set it to measure voltage (V) or resistance (Ω). Test it by touching the probes together to see a zero reading.
  6. Test for voltage.
    1. Carefully touch the black (negative) probe to the neutral bus bar (a metal strip with screws where the white wires are connected) and the red (positive) probe to the terminal screw of the breaker you are testing.
    2. A properly functioning breaker should show a reading close to your home’s voltage (typically 120V or 240V).
  7. Test for continuity.
    1. Set the multimeter to continuity mode
    2. Place one probe on the screw terminal of the breaker and the other on the load terminal (where the wire connects to the circuit).
    3. The multimeter will beep if there is continuity, indicating the breaker’s internal connections are intact. No beep means the breaker is likely faulty and should be replaced.

Interpreting the Results

If you get a normal voltage reading but the breaker still trips or doesn’t work correctly, there may be an issue with the connected circuit or appliance. If you get no voltage or continuity, it’s a strong indication that the breaker is faulty and needs replacement.

Whether you need an electrical panel replacement or a quick repair, the certified electricians at Mr. Electric are happy to help. Call now for an urgent electrical repair service or to schedule an appointment for a better time.