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What is a Grounded Extension Cord? (Detailed Explanation)

Written by Edwin Jones / Fact checked by Andrew Wright

what is a grounded extension cord

If you’ve ever come across an extension cord before, it’s likely that the question “What is a grounded extension cord?” also popped into your mind. No? Well, even if the question didn’t materialize that time, you’re here, so your curiosity is undoubtedly piqued.

A grounded extension cord is one that has a third wire and prong intended for grounding. It adds a safety net or a return path to the ground for excess current. It’s usually found in your standard medium and heavy duty extension cord available at a hardware store.

What Makes a Grounded Extension Cord

An extension cord with ground or one that has a middle prong, as some folks like to call it, prevents the risk of electrocution that may arise due to a short circuit and other fault conditions.

It contains both the hot and neutral wires connected to the right and left prongs, respectively, but it also throws in the additional ground wire connected to the said middle prong.

An extension cord without ground or one that’s two-pronged and not double-insulated fails to impart this valuable safety benefit.

Why Do Extension Cords Need to Be Grounded?


It’s a given that we all want to prevent electric shocks as much as possible from occurring in our homes. These electrical issues may even become fire hazards at times.

The reason why there’s an extension cord ground prong is mainly to ensure safety while operating any grounded appliances connected to it. Usually, these are the typical metal-encased ones that also come with a grounded plug.

Of course, a 3 prong extension cord has to be plugged into a grounded outlet to work properly. Technically, it’s the ground wire and prong of the cord that “unlocks” the advantage and purpose of the said outlet type.

This rings true for any plug that’s grounded, extension cord or otherwise.

Overall, we rely a lot on extension cords to address distance issues when powering our tools and appliances. It’s only right that they should be integrated with the necessary protective capabilities with regard to grounding as well.

What Happens if the Extension Cord Isn’t Grounded?

There are numerous scenarios to consider to answer this question correctly and in detail. They are the following:

  • If you plug a two-prong or light-duty device (i.e. one that doesn’t require grounding) into the extension cord, then it should work fine and safely.
  • Another type of appliance or tool that works well with ungrounded cords is one that’s confirmed to be double insulated. You should be able to tell whether an appliance is double insulated or not by keeping an eye out for a double box symbol (one smaller box inside a bigger one) printed on it.

Take note that such appliances will likely have only two-prong plugs. It’s completely alright to plug them into a grounded and ungrounded appliance extension cord.

As for why this is so, it’s all thanks to the plastic casings incorporated in the appliance. They function as effective insulators that absorb all the excess electricity that may shock you once you touch or come near the appliance. Metal-cased appliances do the exact opposite. 

  • Ungrounded cords should also work if there are no fault conditions that happen as you’re operating the appliance. Once they do rear their ugly heads, though, you’re in for a literal shock! Usually, faults occur if the appliance you plug into the extension cord exceeds its wires’ rated ampacity.
  • If you plug an appliance that needs grounding (such as fridges and dishwashers) into an extension cord that isn’t grounded, then you’re inviting electrocution. This underscores the importance of knowing which type of extension cord to use (two-prong or three-prong) based on your appliances’ individual loads.

Lastly, you may be wondering what causes the electric shocks in the first place. Typically, they happen because the appliance’s wires come in contact with its casing. Only a ground wire in an extension cord or proper insulation can prevent them.



Do grounded extension cords protect from electrical shock?

Yes, they’re grounded precisely for that purpose. However, grounded extension cords do not so much provide direct electric shock protection as they help to prevent most appliances from becoming natural shock hazards when you touch them.

When should you use a grounded extension cord?

You have to use a grounded outdoor or indoor extension cord for any tool or electrical equipment that needs grounding. You’ll be able to tell this immediately if they come with a three-prong plug. An exception can be made for double-insulated devices.

That being said, it’s never advisable to use a 3-prong appliance with an ungrounded extension cord.

Is it ok to use an extension cord without a ground?

It’s only safe to use ungrounded cords with light-duty, simple appliances like alarm clocks and small lighting fixtures, assuming you’re sure that the devices are still in good, working condition. Two-prong appliances, especially double-insulated ones, should be fine as well.

Have you ever entertained the thought of removing the ground prong on a plug? I hope you block it out for good because doing so is equivalent to putting yourself in direct danger from electrical shocks.

Grounded vs ungrounded extension cord

Ungrounded cords are far riskier to use than their grounded counterparts. The third grounded extension cord wire is there to help protect against shocks from metal-cased appliances, after all.

Don’t chuck away your ungrounded extension cord just yet, though. They’re still okay to cover the lengths required to power small appliances that don’t need grounding (i.e. those that aren’t medium or heavy-duty).

Are all three-pronged cords considered grounded?

You have to remember that it’s not so much the presence of the prong that matters. It’s just one part of the safety blanket, after all. Where will the extra current surge flow if there’s no ground wire?

That’s important to highlight, since some people falsely think that by just modifying a two-prong plug into a three-prong plug, the cord will already be considered grounded. That’s still an ungrounded cord because there’s no third ground wire!

If you’re working with a three-prong plug that’s been specifically manufactured that way, you can expect it to have the third ground (green) wire; hence, it’s confirmed to be a grounded safe extension cord.


Asking seemingly basic questions like what is a grounded extension cord?” is always a step in the right direction for anybody. After all, just by discussing this topic, we’ve all learned that:

  • Grounded extension cords keep us safe from electrocution when running our appliances.
  • Not all tools and devices work with ungrounded extension cords. We’ve even learned that it’s not exactly safe to use them most of the time.
  • You always need to have a basic awareness of your electrical loads and what your specific appliances need when plugging them into various outlets.

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