What to do if the Lights Are Dimming with the Microwave On? (3 Likely Scenarios + Easy Fixes)

You’re ready for a quick and easy, microwaveable meal. Yet every time you turn the microwave on, all the lights in the room begin to dim! If you’re a bit worried or curious about this problem, you’ve come to the right place. We’ll explain everything you need to consider when you notice that the lights are dimming with the microwave on, as well as how to fix it!

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 due to an overloaded circuit. The only solution to this problem is to remove some of the devices plugged into the circuit to decrease the load.

Read on to find out more about the lights dimming with the microwave on and to learn what to do about it.

Why the lights are Dimming with the Microwave On

Sometimes, while using appliances like the microwave, you will notice a dip in power to other appliances and lights plugged into the same circuit.

If you’re curious to learn why the lights are dimming with the microwave on, read through the three possible reasons listed below, and learn exactly what you ought to do to fix it in each situation.

• Wiring in the house is too old
• The microwave is connected to an overloaded circuit
• There are loose wires in the wall outlet or breaker

1. The Wiring in your house is too old to support the load you’re placing on it

If running your microwave causes all the lights in the house to dim, then it’s probably a fault in the main panel or something further upstream. It’s likely that if this is the case, the wiring in your house is extremely old, and it’s not able to support the load you’re attempting to place on it.

What to do if the wiring in your house is too old

If running the microwave causes all of the lights in the house to dim at the same time, there really isn’t a lot you can do. This indicates some serious issues and probably wear and tear with your entire electric system.
If this is the case, contact a qualified electrician. You may have to contact the power company.

If it’s only a few lights, then the fault is probably limited to an individual circuit. Proceed to explore the scenarios below.

2. The microwave is connected to a shared Circuit that can’t support the load

If the microwave oven is connected to the same electrical circuit as the lights, and that circuit gets overloaded, then the lights will dim when it is switched on. A microwave draws a fair amount of power. If you have it plugged into a GFCI outlet, then using it at the same time as another appliance will likely only trip the breaker.

However, if you don’t have a ground fault circuit interrupter installed, it will probably cause dimming.

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

What to do if the microwave is connected to a shared circuit and causes dimming

To fix the dimming problem in this case, connect the microwave to a dedicated or high amperage circuit and check if this stops the dimming. Placing the appliance on a dedicated circuit will eliminate the possibility of an overloaded circuit.

If you try this and still experience problems, you’ll need to consider another cause.

3. There are loose wire connections at the wall outlet or to the breaker

If there are loose wire connections at the wall outlet or to the breaker on the main panel, you may also experience some light dimming while running the microwave. Ask yourself the following questions.

Have there been any recent changes or additions to your electrical wiring?

How long has it been since these outlets were wired?

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. This is the final possible cause.

What to do if there are loose wire connections at the wall outlet or to the breaker

In most cases where you’re able to identify this as the problem, you’ll probably want to contact a qualified electrician to inspect and ensure that all wire connections from the main or subpanel to the wall outlet are firm.

This can be done yourself, but there are certain dangers associated with this type of job. Always make sure the circuit is shut off from the main panel before beginning any electrical work. Simply remove the outlet covers and use a multimeter to test each wire for a current before beginning your work.

Check each connection, and make sure the copper wiring isn’t too frayed to provide a proper connection. Check each outlet on the circuit to find the culprit(s) of the problem.

Summary of what to do if the lights are dimming with the microwave on

If you notice the lights are dimming with the microwave on, the phenomenon may be caused by an internal wiring problem, such as a loose wire connection or an overloaded circuit.

It is also possible that the fault is further upstream with the service feed to the house. If this is the case, you’ll want to contact the power company, though this scenario is unlikely. If you feel uncomfortable doing electric work yourself, always contact a qualified electrician.

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