Do USB Sockets Draw Power When They’re Not In Use?

USB ports have become one of the most common cable-to-device connections. You can find them in cars, airports, hotels, and shopping centers worldwide. More and more electronic devices use a USB connection over any other. 

Yes, USB sockets draw power, even when there’s no device plugged in. But how much is it, and is it worth the convenience? In this guide, we’ll answer those questions and provide a few tips that can help you minimize the power draw. 

Understanding USB Socket Power Consumption

USB stands for Universal Serial Bus. USB is the standard for short-distance digital data communications. This dual-ended design can give power and transfer and receive data, depending on the port location and the device plugged in. 

USB chargers, like smart bulbs and home assistants, are vampire devices, meaning that they draw power even though nothing is turned on or in use. Technology like smart bulbs and home assistants have internal circuitry and a standby mode that keeps the computer components on demand. USB charging blocks, like AC chargers, have internal circuitry. Standard outlets and receptacles have neither.

When the charging block components moved from the external to the socket, the internal circuitry moved into the receptacle. Unlike a standard outlet, the socket draws an idle current. The phantom power drawn from USB ports is about 0.05 watts (W) when nothing is plugged in. By comparison, a 60 W light bulb will use 60 W of electricity, so a USB outlet uses very little power. This idle current amounts to only a few cents of electricity per year.

Factors Influencing USB Socket Power Usage

Electricity rates in Los Angeles are some of the highest in the country. Though the idle current from a USB socket doesn’t amount to excessive power consumption, some factors can increase the power draw and your electricity bill. 


By itself, a USB cable draws very little power. It’s usually safe to leave plugged in and not likely to cause equipment damage.

Anything plugged in

If a device is plugged into a USB port, it will draw power, even when it’s not on. How much power it draws depends on the device. USB-connected printers, broadband, and modems continue to draw as much power as is needed to keep them on standby.

LED indicators

These indicators use electricity so it’s impossible to avoid a current draw, but this isn’t enough to significantly increase your electricity bill or cause a safety issue.


A cheap outlet can have faulty or low-quality current control measures. As the socket draws power, it overheats and can damage the outlet or device. Low-quality USB sockets can also take longer to charge devices. 

The USB port type

The type of USB outlet impacts the standby power draw. A USB 1.0, 1.1, or 2.0 outlet uses 0.5 amps (A) of power while a USB 3.0 unit uses 0.9 A and a USB 3.1 outlet uses 3 A. The more amperage an outlet supports, the faster it can charge a device, depending on its requirements. For example, smartphones need just 1 A while tablets need 2.1 A.

Measuring and Assessing Power Draw

A hardwired USB socket offers convenience and efficiency when it’s managed properly. Quality receptacles and diligent device use can limit the power draw. If you want to know how much power your receptacles and devices draw, you can measure them.

A high-end home electricity usage monitor can measure everything from the power factor to the minimum and maximum power (W). It can also measure amps and volts. This is particularly useful when you want to confirm how much power an active device uses. 

These compact devices plug into any standard receptacle. They usually have a digital display and a variety of common receptacles. To use an electricity usage monitor, plug in the device in question and the information shows up on the display.

There are hardwired smart receptacles that measure electricity usage and send the data to an app on your tablet or smartphone. 

Even with the data, it’s not always easy to understand what it all means to the bottom line of your electricity bill. The experts at Express Electrical Services can help. Our licensed electricians have advanced tools to measure your power consumption, identify your power vampires, and suggest upgrades that could help make your home more efficient. 

Energy-Efficient USB Sockets and Chargers

If this discussion has you thinking about ways to make your home more power-efficient, it’s time to talk about your options. 

There are many energy-efficient USB sockets and charging devices on the market today. The first choice for most is the simplest—upgrading your devices and chargers. But, changing your receptacles to high-quality modern models with USB ports can offer long-term savings. 

Our certified electricians can make experience-based recommendations about the best receptacles for your needs. Not everyone is comfortable with smart receptacles. Sometimes all you want is an efficient plug, and nothing else. We can help you find an affordable solution for your needs.

Tips for Reducing USB Socket Power Drain

You can reduce your USB charger energy usage by following these tips:

  • Unplug devices when not in use
  • Don’t leave devices charging overnight
  • Use energy-efficient chargers and devices
  • Upgrade your receptacles to power-smart models

When To Call an Electrician

A USB socket is an electrical receptacle — it requires wiring work to install. They are easy to install if you have experience with electrical work and follow the appropriate safety precautions. However, new receptacles can impact the power draw on existing circuits in your home. Plus, with so many models out there, it’s not always as simple as changing out a standard receptacle. 

Local LA electricians, like the knowledgeable and friendly team at Express Electric. Our licensed technicians are trained in the latest tools and products. We can install USB sockets quickly and safely. We can also install GFCI outlets, new switches, and circuit breakers as well as rewire your home

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Choose the team with 5-star service and see the difference dedicated professionals can make to your home’s energy efficiency. Let us know what you need and our 24-hour electrician can install or repair any outlet or switch in your home.

Contact us today for service in the Los Angeles area and other parts of Southern California.