Light Fixture Circuit Wiring

By Dave Rongey - Summary:

How to Make Electrical Wiring Connections for Home Light Fixtures: Typical Wiring Mistake with Light Fixture and How to Fix It.

Wiring Light Fixtures

Home Electrical Question: I replaced a light fixture and added another onto the same circuit, wiring the second one in sequence through the first one.

  • I also added a dimmer switch to the circuit at the same time.
  • The two fixtures use candelabra-based lights, with one having 3-60 watt bulbs  (the max allowed in the fixture), the other 4-40 watt bulbs (the max allowed in that fixture).
  • I believe the bulbs in each fixture are wired in parallel.
  • The lights all seem quite dim and the 40 watt bulbs look brighter than the 60 watt bulbs. Also, the brightness changes when I unscrew one of the bulbs.
  • Oddly, when I unscrew one of the 40 watt bulbs, the other three on that fixture get brighter, but the 60 watt bulbs in the other fixture get dimmer.
    I have done quite a bit of wiring, and have never seen anything like this.
  • The dimmer is supposed to be able to handle 600 watts, so I didn’t think that would be an issue.
    Should these be wired separately? Should I have made them parallel instead of sequential?

This home electrical wiring question came from: ken, a Handyman from Baton Rouge, LA.

Additional Comments: Very helpful.

Dave’s Reply:
Thanks for your electrical wiring question Ken.

How to Make Electrical Wiring Connections for Home Light Fixtures

Application: Ceiling mounted or wall mounted 120 volt Light fixtures for the home.
Skill Level: Beginner to Intermediate.
Tools Required: Basic Electricians Pouch Hand Tools, a non-aluminum ladder and Voltage Tester.
Estimated Time: Depends on personal level experience, ability to work with tools and access to the light fixture(s).
Precaution: Identify the light circuit, turn it OFF and  Tag it with a Note before working with the wiring.
Notice: Installing additional fixture wiring should be done according to local and national electrical codes with a permit and be inspected.

Typical Wiring Mistake with Light Fixture and How to Fix It

Parallel and Series Wiring and the Effect on Light Fixtures

  • Ken, check your wiring and make sure that all of your connections are parallel. Also check the wring on the dimmer switch and make sure the dimmer is wired properly.
  • If the light fixtures have been wired in series then the light bulbs will not shine bright, but will be dim because each light bulb will act as a resistor and restrict the full power of the electrical circuit.
  • Parallel wiring is where each light fixture is wired independently to the circuit wires with the typical connections of white neutral to white neutral wires, and black power to the black power wire.
  • There may be a deviation of the electrical circuit wiring depending on the location of the home and the methods that have been used to install or modify the light fixture circuit wiring.

More about Electrical Wiring for Light Fixture

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For more information about Troubleshooting

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Be Careful and Be Safe - Never Work on Energized Circuits!
Consult your Local Building Department about Permits and Inspections for all projects.


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