Can I Use 15 Amp GFCI on 20 Amp Circuit: The Simple Answer

Your outlet is loose, and it’s time for a change. You picked up a 15 amp GFCI, but the circuit is 20 amps, is it okay to use what you have? If this is your first time doing this kind of electrical work, then it may seem a little intimidating, but don’t let that get you down. Replacing a simple outlet is something many homeowners can handle on their own. It’s not difficult if you have proper instructions, and replacing a GFCI is a relatively straightforward intermediate skill level upgrade. Better still, you can save money on these sorts of minor home repairs when you don’t need to hire a professional electrician. I’ll walk you through all the tools and details you need to know about this type of electrical DIY so you can swap that outlet with no problems.

Can I use 15 amp GFCI on a 20 amp circuit? You can use a 15 amp GFCI on 20 amp circuit because it uses less power than that circuit is capable of putting out. However, it’s essential to know that a dedicated twenty amp circuit with only one outlet requires a twenty amp ground fault circuit interrupter (GFCI). Also, it’s vital to remember that the reverse is not true because a twenty amp GFCI would pull more power than you have and blow the circuit. 

Why You Can Install a 15 Amp GFCI on a 20 Amp Circuit

Installing a 15 amp GFCI on 20 amp circuit is relatively simple. I’ll walk you through it step by step in a moment. However, before we get there, let’s discuss what you’re looking at. For those who don’t already know, this is vital. As this is an intermediate skill level electrical project, you should already know these things. If any of the following information is surprising or new to you, please ask an electrician for assistance.

Amperage or amps is exactly how much power runs through a ‘thing.’ In this case, we’re looking at an outlet. Because it’s transmitting power instead of drawing it out, your outlet won’t necessarily have anything plugged into it that draws all fifteen of those amps.

Most homes in the USA have hundred-twenty amp circuits that use a combination of 15-amp and 20-amp plugs. In fact, you can run multiple outlets capable of pulling more than a hundred-twenty-amps when combined. However, you can’t plug-in and run more than the circuits amp maximum between them. If you do, then you’ll trip the breaker.

The circuit breaker is what limits your amps to help keep a safe amount of power flowing in your home. Without a breaker, you could overload devices by merely plugging them in. Furthermore, the chances of electrocution and fires would be much higher.

Additionally, if you draw too much power near the circuit, you’ll have issues with degradation down the line. Hence the last outlet on that circuit could have trouble pulling anywhere near the capacity. Regardless of what the outlet is rated, when you have things plugged in on the other outlets pulling too much power, there’s a drain on the circuit.

Before Installing a 15 Amp GFCI Plug

Before you get started installing that 15 amp ground fault circuit interrupter plug, there are three things you should check. Firstly, what type of metal are your wires? If they are aluminum instead of copper, then you should not proceed. Call a professional.

Second, can your existing electrical box accommodate a GFCI outlet? Upgrading a household electrical box is not a simple DIY project. Not only does it require more specialized knowledge and permits, but it’s also not something you can legally do for yourself. Moreover, if you can’t tell whether your box can handle the GFCI, then this project is a little too advanced for your current skill level.

Thirdly, check the outlet you plan to replace. If it hast three holes in each socket, then this is a job for an intermediate DIYer. However, when your current plug only has two holes, you’re going to need to do some rewiring, or rather, a professional electrician should come and handle this project.

Tools You Need

To get started on this project, you should collect your tools together. You don’t need very much to swap out a simple plug. Clearly, you need to have a 15 amp GFCI plug to put one in, but here’s a quick list of the rest of the equipment you’ll need.

  • Circuit Tester- I recommend the Klein Tools ET310 AC circuit breaker finder from Amazon. Because it has an integrated GFCI outlet tester, this is the ideal tool for the job. You’ll be able to quickly find the correct breaker using the visual and audible scanner. Check the reviews right here.
  • Flat-Head Screwdriver- You don’t need anything fancy here. A standard, rubber handled flat-head will do just fine.
  • Phillips Head Screwdriver- Similar to the flat-head, you don’t need any special equipment here, just a rubber handled screwdriver.
  • Flashlight- Working with the power off can be tricky, depending on your location. For example, a basement is a lot darker than most of your home. A high-quality lantern flashlight like the LE Rechargeable LED Camping Lantern will help you get the job done efficiently. Plus, it comes with the USB charging cable. To learn more on Amazon, click here.
  • Rubber Soled Shoes- Always do electrical work with a good pair of rubber-soled shoes for safety.
  • Needlenose Pliers- You may need a set of wire strippers in addition to your pliers. Resultantly I recommend a tool that can handle both jobs easily. The 8-Inch Klein Tools D203-8N Pliers have side-cutting and wire stripping components integrated into the needlenosed pliers, so you won’t need to carry extra tools. Find them on Amazon, right here.

Once you have everything you need together, you can start changing the outlet. I’ve included the steps below for easy reference.


Install Your 15 Amp Outlet

Make sure the power is off before you start installing your 15 amp GFCI outlet on your 20 amp circuit. It may seem like obvious advice, but it’s also crucial to your safety. No one wants to get zapped.

  1. Remove the plate cover.
  2. Test to make sure your outlet is off.
  3. Disconnect the wires.
  4. Remove the old outlet.
  5. Separate the line and load wires. Your load wires will carry power to every other outlet on the circuit, and the GFCI outlet protects those from overloading.
  6. Turn the power on and test each wire.
  7. Turn the power back off.
  8. Connect wires to your new outlet. Line and Load should be marked. If not, white wires go to silver screws. Black wires connect to brass or gold-colored screws. Meanwhile, the ground wire should connect to the green screw.
  9. Put the outlet back into the wall.
  10. Replace the cover.
  11. Turn the power on.
  12. Test your outlet by plugging something in that works. It should turn on. Then press the test button, which should turn it off.
  13. Unplug your test item, lamps and radios are great for this and press the reset button.
  14. That’s it. You have a new 15 amp GFCI outlet installed on your 20 amp circuit.

As you can see, the process of swapping an outlet isn’t very complicated. However, it’s considered an intermediate project because people with little to no knowledge of how their electricity system works could harm themselves severely, cause an electrical fire, or blow a fuse. Plus, it’s essential to know when you need a pro to do the job for you.

How You Can Tell Whether You Have a 15 or 20 Amp GFCI

Telling a 15 amp GFCI outlet from a 20 amp is extremely simple. You only have to look at them. Either one will do the same job of protecting other outlets in the chain from overloading.

If you see two plug holes that are both vertical and a rounded ground hole, you have a fifteen amp GFCI outlet in your hand. The test and reset buttons in the middle show that it’s GFCI. That’s all there is to it.

Meanwhile, a twenty amp GFCI has the same ground, and two other prong holes on each plug. However, one of the prong holes will be shaped like a sideways T. The test and reset buttons will still be in the middle.

How Many GFCI Outlets on One Circuit

There’s no need for more than one GFCI on a circuit. However, you do need GFCI’s anywhere there’s water nearby. Examples include kitchens, bathrooms, and garages.

You should not chain GFCI plugs. If you have any questions about how this works, ask an electrician, or refer to the National Electrical Code for more information.

Final Thoughts

Always exercise caution when wiring a 15 amp GFCI into a 20 amp circuit, or doing any electrical work. Make sure your power is turned off. No one wants to get electrocuted trying to do a simple job.

If you want a visual on how to accomplish the installation, I recommend that you watch this video on how to install fifteen and twenty GFCI outlets. Sometimes seeing the process helps as much as reading the details. Everyone has their own best learning style.

Make sure you check local laws to make certain you’re allowed to do wiring without permits and inspections. Unless you’re an electrician, you have to both own and live inside the home where you plan to DIY any electrical work.

Aron Blake

I am the lead copywriter on Homezesty and the Webmaster. I have a lot of experience in home renovations and the creation of style. I enjoy writing and sharing my tips on how to create the best living environment. My Linkedin Profile, My Twitter Account

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