What Does 120 Volts Mean

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This week we’re gonna answer one of the most asked, yet elusive lighting questions in the industry: Why do certain lights operate on 120 volts versus 12 or 24 volts?

And why does voltage even matter? It’s all about wattage, right? Lights operate on different voltages for specialized purposes, and in America, 120-volt, 12-volt, and 24-volt lighting systems are the most common.

So what are the differences between them? 120 volts is the standard voltage supply for American homes. This is the voltage that travels to your home from your local utility substation.


120 volts is commonly referred to as “line voltage” by electricians and other industry experts. Nearly all indoor residential light fixtures and appliances in the U.S.

run on line voltage. A 120-volt light bulb can typically be screwed into an indoor light fixture and operate correctly without further complication. Likewise, most appliances run on 120 volts and can simply be plugged into an indoor outlet.

Meanwhile, 12 volts and 24 volts are commonly used for outdoor lighting and are referred to as “low voltage” lighting. A transformer (or LED driver for LEDs) is required to "step down" (reduce/convert) the standard 120-volt supply provided to your home into a 12-volt or 24-volt supply for your lights. In most cases, whether you need a 12- or 24-volt light bulb simply depends on the needs of your light fixture: does your fixture require a bulb that runs on 12 or 24 volts to operate?

When it comes to LED rope light, or LED tape light for that matter, you may have the option to choose between a 12-volt or 24-volt light.

The one you need depends on how long you need your rope or tape light to be. The longer your continuous strand of rope or tape light, the more voltage you will need to travel across its entire length without losing brightness (a phenomenon called voltage drop). We discuss 12V vs. 24V tape light further in our LED tape light guide. The reason low voltage lighting is used outdoors is because it’s safer. If the wire for a 120-volt light source (which would run underground or on a building’s exterior, if used outdoors) were to become exposed, it would be very dangerous for someone to come in contact with, possibly resulting in a dangerous electric shock. For a low voltage light source, this risk is significantly reduced and would result in little to no harm in most scenarios. The rule of thumb: if your lights are being used somewhere where the wiring could become exposed, and therefore hazardous, it is always better to opt for low voltage lighting if given the choice.

These are just the three most common residential voltages in America. They are by no means the only voltages that can be used to operate lighting systems or appliances. Many US commercial buildings run on 277 volts, and in Europe, the standard voltage supply is 220 volts—a major reason why American appliances won’t work in overseas outlets.

Some lighting systems require even more volts.

  • When purchasing a new light source, first and foremost, you must always match your light bulb to the requirements of your fixture. Have any questions about line or low voltage lighting? We have an answer! Ask away below and get more lighting updates by following us on Facebook, Twitter, LinkedIn, Pinterest, or Instagram!
  • A 120-volt outlet with built-in covers for safety. The 120-volt power outlet is the standard electrical outlet in use in homes in North America. These outlets have been in use in their present form since the early 1950s.

Advertisement . Video of the Day . The modern 120-volt power outlet has three holes: two parallel rectangular slots—one connected to the "live" wire and one connected to the neutral wire—and a round hole for the ground wire.

Most outlets are "duplex" receptacles, with two places to plug in electrical devices. Advertisement . There are two common styles of 120-volt duplex receptacles.

On "standard" receptacles, each outlet has its own round opening in the wall plate.

  • On "decorator" receptacles, a single plastic rectangle holds both outlets. Advertisement . All modern 120-volt outlets are designed to accommodate "polarized" plugs, on which the rectangular prong for the neutral wire is slightly larger.
  • This is a safety measure designed to control the way an electrical device handles current. Advertisement . Any device that says it runs on 110 volts can be plugged into a 120-volt outlet.
  • The "120 volt" label is just a nominal figure; the actual voltage could be anywhere in the range of 110-125 volts, and modern electrical devices are built to tolerate the fluctuations.
  • Advertisement . Some heavy appliances—such as electric clothes dryers—require 240 volts of power. Outlets that deliver 240 volts are configured differently, so devices for 120-volt outlets can't plug in to them. Advertisement . Any time you do electric work in a home, or even need or want to move your appliances around, you need to understand the difference between 120 and 240 volt outlets.

You will find them both in your home; but how are they actually different, and why do you need to know the difference to begin with?

That’s what this post will examine. Understanding Electrical Currents. Think of electrical currents in your home as pressure. The more quickly and harder the individual electrons are pushed through your electrical wiring, the more power they will provide to the outlet.

Of course, that means you have to be very careful. Not every electrical wire (and outlet) can handle higher voltage, such as 240 volts. Ignore that fact, and your conductors can overheat, leading to significant fire hazards. You can distinguish between a 120 volt outlet and a 240 volt alternatively relatively easily. The first image that comes to mind will tend to be 120 volt; it’s the one you use to plug in anything from your vacuum cleaner to your phone charging cable. A 240 volt outlet, on the other hand, is larger, with room for three individual plugs or four plugs of varying size. You may think that the safe route, then, is to simply go with 120 volt outlets throughout your home.

But as it turns out, both the 120 volt and 240 volt alternatives can be beneficial, depending on your needs (and appliances).

  • When 120 Volt Outlets Are Enough. Most everyday appliances only need enough electricity for a 120 volt outlet.
  • Microwaves, refrigerators, and dishwashers are examples of examples that will function perfectly fine on 120 volt outlets.
  • You will recognize these outlets anywhere in your home. In fact, if you don’t know that there are two types of outlets, these will be the ones that you think of as ubiquitous. But in some situations, 240 volt wiring and outlets may be required.
  • When You Need 240 Volt Outlets. A number of your appliances require more than 120 volt to run adequately and reliable.

Your washing machine, dryer, and oven/range are the most common examples. All of them will technically run on 120V, but they won’t be nearly as effective; in fact, an oven that is connected to a 120V wire will only produce 1/4 the heat it would produce if connected to a 240 volt outlet.

For your home, that means planning your electricity carefully is an absolute necessity. You need to know exactly where your stove, washing machine, and dryer will be located in order to ensure that your wiring is adequate for optimum function.

  • Should you ever need to replace an outlet or wire, you need to know what type of conductor and wire strength will be necessary. The Need for Electrical Expertise in Appliance Repair.
  • Every appliance will inevitably break down at some point. No matter how great your new oven or washing machine is, it won’t last forever with the need for repair at some point. If you want to save money and undergo that repair yourself, you need to understand exactly how electricity and the different types of current play into your repair efforts.
  • Put simply, you don’t want to risk messing up the electricity and risking a fire hazard or improperly functioning appliance.
  • As a result, you need to make sure that you can both match the right appliance to the right outlet, and replace the wiring with one of adequate strength if necessary. Any type of appliance repair requires at least some electrical knowledge. Are you confident in yours?

If not, you may want to brush them up. Fortunately, our appliance repair classes can help you do just that.

2 Responses

Deepak Narain

Contact us to learn about your options.

Jesse Anderson

thank you !!

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