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Electrical Wire and Cable

Identifying The Cause Of a Dimming Light Circuit

What is causing my lights to be dim? How to Identify and Fix the Cause of Dim Lights, Dim Lights may be a Indication of an Electrical Problem, How to Check Electric Circuit Wiring.

Home Electrical Wiring Video

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Using a Circuit Breaker Interlock Kit
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Dimming Lights and Electrical Problems
Electrical Question: What is causing my lights to be dim?

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 Certified Electrician or 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.

More about Electrical Wiring, Troubleshooting and Repairs

Circuit Wiring
Circuit Wiring

Electrical Circuit Wiring

This article looks at common 120 volt and 240 volt house wiring circuits and the circuit breakers that are installed identifying the types and amperage sizes used in most homes.
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Home Electric Circuit Breakers

Home Electrical Circuit Breakers

A guide to home electrical circuit breakers and how they work to protect your electrical wiring. When properly installed, your home electrical wiring is protected by a circuit protection device.

Using Testers to Identify Electrical Problems

Testers to Help Solve Electrical Problems

How to Troubleshoot Electrical Wiring Problems
Types of Electrical Testers

Understanding Digital Volt Meters

When working on home electrical wiring using voltage meter can play an important part in electrical safety. Electrical testers and voltage meters enable you to identify electrical circuits and help prevent the possibility of accidental electrical shock.

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Dave's Guide to Home Electrical Wiring:

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Here's How to Do It:
Wire It Right with the help of my Illustrated Wiring Book

Great for any Home Wiring Project.
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Complete Guide to Home Electrical Wiring

Perfect for Homeowners, Students,
Handyman, Handy Women, and Electricians
Wiring GFCI Outlets
Wiring Home Electric Circuits
120 Volt and 240 Volt Outlet Circuits
Wiring Light Switches
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Consult your Local Building Department about Permits and Inspections for all Electric Wiring Projects.

Electrical Tips to Help You Wire it Right

The Safest Way to Test Electrical Devices and Identify Electric Wires!

The Non-Contact Electrical Tester
This is a testing tool that I have had in my personal electrical tool pouch for years, and is the first test tool I grab to help identify electrical wiring. It is a Non-contact tester that I use to easily Detect Voltage in Cables, Cords, Circuit Breakers, Lighting Fixtures, Switches, Outlets and Wires. Simply insert the end of the tester into an outlet, lamp socket, or hold the end of the tester against the wire you wish to test. Very handy and easy to use.

The Quickest Way to Check for Faulty Electrical Wiring!

The Plug-In Outlet Tester
This is the first tool I grab to troubleshoot a problem with outlet circuit wiring. This popular tester is also used by most inspectors to test for power and check the polarity of circuit wiring.
It detects probable improper wiring conditions in standard 110-125 VAC outlets Provides 6 probable wiring conditions that are quick and easy to read for ultimate efficiency Lights indicate if wiring is correct and indicator light chart is included Tests standard 3-wire outlets UL Listed Light indicates if wiring is incorrect Very handy and easy to use.

Strip Off Wire Insulation without Nicking and Damaging the Electric Wire!

The Wire Stripper and Wire Cutter
My absolute favorite wire stripping tool that I have had in my personal electrical tool pouch for years, and this is the tool I use to safely strip electrical wires.
This handy tool has multiple uses:
The wire gauges are shown on the side of the tool so you know which slot to use for stripping insulation.
The end of the tool can be used to grip and bend wire which is handy for attaching wire onto the screw terminals of switches and outlets..

The wire stripper will work on both solid and stranded wire. This tool is Very Handy and Easy to Use.

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FAQs Frequently Asked Questions and Comments

10 Responses to “Identifying The Cause Of a Dimming Light Circuit”
  1. 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?

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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,

  7. 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.

  8. 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,

  9. 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.

  10. 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,