Identifying The Cause Of a Dimming Light Circuit


By Dave Rongey - Summary:

How to Identify and Fix the Cause of Dim Lights: Dimming Lights may be a Indication of an Electrical Problem, How to Check Circuit Wiring.


Dimming Lights and Electrical Problems

Electrical Question: There is one circuit in my home that dims than regains power several times in a row.

Please reply ASAP.

Thank you
Background: Greg, from Massapequa, New York.

Electrical Question #2: I would like to know why everything gets dim in my house when the microwave is turned on, or the dryer is started.

This electrical wiring question came from Ken in Irwin, Pennsylvania.

Dave’s Reply:

Thanks for your electrical questions Ken and Greg.

Dimming Lights may be a Indication of an Electrical Problem

Application: Troubleshooting and Repairing Circuit Problems.
Skill Level: Intermediate to Advanced – Best performed by a Licensed Electrician.
Tools Required: Basic Electricians Pouch Hand Tools, Voltage Tester or Volt Ohm Meter or plug-in circuit analyzer.
Estimated Time: Depends on the age of the home and the condition of the electrical wiring and access to the circuit wiring to be inspected, evaluated and repaired.
Precaution: Identify the outlet circuit at the electric panel, turn it OFF and then Tag it with a Note before performing any wiring inspections or electrical repairs. If an outlet or the electrical wiring is found to be damaged then repairs and replacement parts should be obtained with the same voltage and amperage rating. Working in an electric panel is dangerous due to arc flash hazards and the possibility of electric shock.
Notice: Burnt or damaged electrical wiring and circuit components should be replaced with new electrical materials of the same voltage and amperage rating.

How to Identify and Fix the Cause of Dim Lights

Yes, this could be a fire hazard so I would encourage you to have this taken care of asap.

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FAQs Frequently Asked Questions and Comments

10 Responses to “Identifying The Cause Of a Dimming Light Circuit”
  1. Dave Rongey says:

    Hi Daniel,
    If the lights go dim when you reset the circuit breaker for the fridge then there may be something wrong with the fridge. Typically the fridge is on its own circuit, however if possible, you may try plugging the fridge into another circuit to see if the problem is actually the fridge.
    If the fridge runs OK then there is a problem with the original fridge circuit, or something else that is connected to the circuit.
    If the fridge keeps tripping the circuit then there is a problem with the fridge and you should consider calling a service technician.
    I hope this helps you,
    Dave

  2. Daniel says:

    Hello I’m having a problem with my fridge which trips the circuit breaker, and then when I reset the breaker my lights go dim. Do you have any hints were I could start? Thanks.

  3. Dave Rongey says:

    Hi George,
    This sounds like the electrical system is experiencing a feedback due to a lost connection within one of the circuits, or a problem at the electrical panel, or a problem with the electrical service to the home. The situation should be evaluated by a Certified or Licensed Electrician who is experience with electrical troubleshooting. Until the problem is identified and repaired the circuit to the items and devices you have described should be turned off, and the devices should be disconnected or unplugged to avoid possible damage.
    Be Safe,
    Dave

  4. George Grussi says:

    This morning my bedroom lights went dim. The cable box was on but my TV was not coming on. The bathroom fan and lights seem to be losing power, and everything in the bedroom looks like if t was not getting enough power.

  5. Dave Rongey says:

    Hi Bill,
    Consider having a series of voltage readings made to see if there is a difference between the morning and the afternoon. The voltage readings may be made by your local electrical service provider, and I’m sure they would be interested if there is a problem on their end.
    I hope this helps,
    Dave

  6. Bill says:

    I work in a commercial building. The lights on one circuit are dim in the morning, but by late afternoon they are bright again. I had an electrician come in and he tightened all the connections but this fix only lasted a month.

  7. Dave Rongey says:

    Hi Scott,
    This condition of a low voltage reading on the 240 volt dryer circuit is due to loosing one conductor of the 240 volt circuit. The electric dryer circuit wiring and connections should be inspected and tested starting at the panel and throughout to the dryer outlet. This is best repaired by a qualified electrician who is experienced with circuit failures and the safety precautions involved during inspecting the circuit components.
    Dave

  8. Scott culp says:

    Here in the past few days when my dryer comes on it dims the light or even trips the breaker. I check the volts at the arc fault breaker and it shows 104. I have a 200 amp service. I check the phases and one reads 106 the other 141 what is the problem.

  9. Dave Rongey says:

    Hi Brenda,
    When lights dim when a motor driven appliance is turned ON, in this case the disposal, this may indicate that the circuit for the disposal is shared with other devices such as the sink light. Typically the disposal is on a 20 amp circuit that is shared only by the dishwasher. Dim lights may also indicate that the main electrical service may be too small, especially with older homes that have older electrical systems. This condition could also caused because the disposal is old and is not performing optimally, which can be checked by taking an amperage measurement and comparing the readings to the electrical specifications found on the label of the disposal.
    Dave

  10. Brenda says:

    Every time I turn on the switch for the garbage disposal the lights above my sink flash. I had an electrician check it and he said that is normal and nothing to worry about. Is that true?