Flickering and Dimming Lights

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Have you ever experienced flickering lights? Or are you a tech who has had a customer complain about their lights flickering and dimming all of the time? What causes lights to dim and flicker? There are several things that could cause lights to flicker. Here are a few steps to take to troubleshoot your flickering lights. So, if you are looking to find out “what causes lights to dim and flicker,” keep reading.

As a homeowner the first thing you should notice when you see flickering lights is how many are flickering. Is it just one fixture, one room, or is it all of the fixtures in the house that are flickering and dimming? If it is just one fixture then change the light bulb and see if that fixes the flickering problem. If that does not fix the flickering then you need to consult with an electrician. Flickering lights are in every room means you need an electrician possibly need to call your electric service provider.

Now, for meter tech’s or lineman. When troubleshooting flickering and dimming lights you ask the customer the same questions as above. Where are the lights flickering? How many? How often?

What causes flickering lights?

Well, one of the most common causes of flickering lights and dimming lights is tree limbs on the primary. This can cause the lights to flicker because the current that is supposed to be feeding homes will be creating giant blue arcs. If this is happening, generally there will be several customers complaining that their lights are flickering or they have dimming lights.

The next most common cause of flickering and dimming lights is a loose neutral. When a customer has a loose neutral their service loses its reference to ground. Most homes have a 120/240v service. This means that when you use a voltmeter to check for the proper voltage you should get 120v when measured from each phase to ground and 240v when you measure between both phases.

The ground is the reference point in this service and when it is lost either by a loose connection or by a corroded or broken neutral wire, this reference is gone which results in what is known as a “floating neutral.” When this happens if you were to check the voltage from phase to ground you could get anything from 0v to 240v. This is what causes the lights to flicker off and dim. They can even get brighter and burn out.


The first thing to do when you pull the meter out is to do a quick visual inspection of the meter base. If there is a loose neutral sometimes you can identify it visually. I have found a loose neutral more than once just by a quick visual inspection. To find a loose neutral visually just look for a connection that does not look tight because the connector is not on straight.

Another thing you are looking for when you are trying to find a loose neutral is corrosion and overheating. If you see this, you can bet that this is the problem that is causing the flickering and dimming lights. Next, if everything looks good and you are sure that you do not have a loose neutral, go ahead and check all of the connections and make sure they are tight. A loose electrical connection creates heat which can lead to a hot socket and that is not good for electrical equipment. A loose connection on the phase legs can also cause the lights to flicker as well.

A tool that can be used to check for a broken or loose neutral is called a neutral tester. It puts a load on each phase and shows a change in the phase to ground voltage. Typically if there is a broken or loose neutral, the change will be drastic and you will be able to identify it right away. Flickering lights are generally a good indication that something is wrong with the neutral.

If you find a neutral problem and it is on the utility side you will want to get it repaired as soon as possible because a bad neutral can burn electrical equipment up very quickly.

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