What To Do When The Main Circuit Breaker Trips Off

By Dave Rongey - Summary:

How to Identify an Electrical Problem: Tripping Main Circuit Breaker or Blown Fuse, What to do About a Home Electrical Problem.

Tripping Main Circuit Breaker

Electrical Question: The main switch in the fuse box has shut off three times, what could cause this?

  • I live in a house built in 1970.
  • In the past two days, the main switch in the fuse box has shut off three times.
  • What could cause this and what is the best way to repair the problem?

This home electrical question came from: Kandi, a Homeowner from Houston, Texas.

Dave’s Reply:
Thanks for your electric wiring question Kandi.

Troubleshooting the Cause of a Tripping Main Circuit Breaker

Application: Electrical Troubleshooting, Testing Electrical Circuit Wiring.
Skill Level: Intermediate to Advanced – Best performed by a Licensed Electrician.
Tools Required: Basic Electricians Pouch Hand Tools and Voltage Tester or Continuity Tester.
Estimated Time: Depends on experience and level of problem solving skills.
Precaution: Testing live wires is dangerous and should be done by an experienced individual only. Testing using a continuity tester should only be made after the circuit has been identified and turned OFF and Tagged.

Tripped Main Breakers and Electrical Circuit Problems

  • A main circuit breaker can trip off for a variety of reasons, including a direct short within the home electrical system, or an over loaded condition of the electrical system.
  • The cause of the tripping circuit breaker can be isolated simply by turning off all the other circuit breakers, resetting the main circuit breaker, and then turn on the other circuit breakers one at a time.
  • When the circuit breaker has been turned which has a fault or direct short then the main circuit breaker will trip off again.
  • Identify the circuit breaker that caused the main circuit breaker to trip off and leave the affected circuit breaker off, then once again, reset the main circuit breaker and turn on all of the other circuit breakers.

What to do about a Electrical Circuit Problem

  • Now that the problem circuit has been identified the cause of the problem will need to be discovered.
  • The panel index should indicate what the problem circuit is being used for which will be start the process of investigation about what may have recently been connected to this circuit, or if existing components are at fault.
  • If the problem circuit supplies power to several devices such as outlets or lights then there many be a problem with one of the devices, so the faulty device will need to be identified and repaired.
  • If the problem circuit is an isolated circuit that supplies power to one specific unit then the unit will need to be tested and inspected to identify the fault and the necessary repairs  will be required.
  • In depth testing and analysis may be required to locate the fault.
  • Electrical faults are best discovered by an experienced licensed electrical contractor who preform the required corrections or repairs to get the home electrical system functioning properly.

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FAQs Frequently Asked Questions and Comments

One Response to “What To Do When The Main Circuit Breaker Trips Off”
  1. Forrest Brown says:

    My main panel 240V, 100A Seimans breaker would periodically trip off at very odd intervals. None of the normal trouble-shooting techniques worked. The problem was eventually traced to a combination of when the outdoor temperature was in excess of 95F and running the A/C unit or the Clothes Dryer. (The House built in 1985). Thermal trip units are supposed to be compensated for ambient temperatures, but it turns out that the Main breaker was sort of getting tired on hot days (so do I, come to think of it). Problem solved by replacement.


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