Lights Dimming with Microwave On? (Here’s How to Fix it)

Each time you switch on the microwave, the lights in the kitchen go dim and only return to their usual brightness when the microwave goes off.

Is this normal? What causes this and how can it be fixed?

This post explains the possible reasons why the lights may dim when the microwave is on and what you can do to fix them.

Note: This post makes references to checks on the house wiring. Consult a qualified electrician.

Always follow recommended safety procedures when working with electricity.

Quick Answer

The most likely cause of the dimming of the lights when a microwave is switched on is there is a voltage drop in the electrical circuit supplying power to the microwave.

Read on to find out what causes this.

Why Do the Lights Dim when the Microwave is On?

If the lights dim, check the following:

#1. Is it all the lights in the house that dim or a few lights? If it is all lights then it’s probably a fault in the main panel or all further upstream. Contact a qualified electrician. You may have to contact the power company.

If it is a few lights then the fault is probably limited to an individual circuit. Proceed to explore the following.

#2. Check if the microwave is connected to a shared or dedicated circuit. If the microwave oven is connected to the same electrical circuit as the lights, then there’ll dim when it is switched on.

This problem can be exacerbated If the LED lights are connected to a dimmer switch, which makes them more sensitive to voltage fluctuations.

Connect the microwave to a dedicated or high amperage circuit and check if this stops the dimming.

#3. Loose wire connections at the wall outlet or the wire connections to the breaker on the main panel. Have there been any recent changes or additions to your electrical wiring?

The lights can dim if there’s a loose or weakly connected wire such as a bad neutral wire connection at the wall outlet or the main panel or sub panel.

Contact a qualified electrician to inspect and ensure that all wire connections from the main or subpanel to the wall outlet are firm.

Closing Thoughts

The dimming of lights when the microwave is running may be caused by an internal wiring problem such as a loose wire connection or an overloaded circuit.

It is possible too that the fault is further upstream with the service feed to the house. Always contact a qualified electrician.

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