a voltage tester connected to a residential breaker box


Originally contributed by • last updated 3/5/2021


Whether we’re charging our phones or running a jigsaw, consuming electricity is something that most of us do on a daily basis. However, it’s not everyday that we are required to understand electrical terms, such as voltage or amperage. But having a basic grasp of how electricity works and the terms used to talk about it can not only help prevent damage to your appliances and devices, it can also help you identify and fix problems on your own.


In a technical sense, voltage (volts), which is often referred to as the potential difference, is the electromotive force that’s needed to move a unit of electric charge through an electric circuit. When talking about your home’s electrical system, the term refers to the amount of pressure that pushes the electric power from the breaker box through a house’s electric circuits to any connected fixtures, appliances, or plugged in devices. By comparison, if an electric current were thought of as a river, the term would be similar to the force carrying the water downstream. Testing the voltage in your home’s electric circuits is often done, typically by a professional, using a non-contact voltage tester.

What Is Voltage Drop?

If you’ve ever plugged in a device to an outlet and suddenly had flickering lights or dim lights, you’ve probably experienced voltage drop. When it happens, it may seem harmless enough, but it can be a serious concern and the causes should be identified and fixed immediately:

  • If an electric circuit has too much electrical load on it (i.e. too many devices drawing power at the same time), there is potential for voltage drop to occur, which could result in lights dimming, devices overheating, and increased electrical consumption.
  • In some cases, voltage drop may be the result of a bad connection somewhere along the circuit. Improperly wired or loose connections on electrical outlets and fixtures can not only cause it to happen but are often the source of electrical fires and should be fixed immediately.
  • In certain cases, electricians may need to fix the problem using a voltage calculator to determine the proper wire size for an electrical circuit based on the amount of drop and current carrying capacity of an electrical circuit.