Extension Cord Safety: 5 Easy Rules You MUST Follow

Extension cords are an accepted and ubiquitous part of modern life in technologically advanced parts of the world.

Extension cords help you access electrically-powered devices without being right next to an outlet, allowing greater convenience and ease of use for any appliance that needs to be plugged in to work.

Given how useful and widely used they are, then, it follows that using extension cords safely is extremely important to avoid accidental injury and property damage.

If you’re not 100% sure that you’re using extension cords safely, then keep reading, because we’re about to arm you with the understanding and knowledge to do just that.

Extnesion cord and power equipment on outdoor table

5 Basic Safety Rules for Using Extension Cords

There’s more to consider than you might think when it comes to extension cord safety; these are high-capacity live electrical wires we’re talking about after all.

Thankfully, though, much of what you need to know is fairly straightforward and intuitive, and a few easy-to-understand rules and guidelines will serve you well whenever you’re working with extension cords.

Let’s take a look:

  • ALWAYS check your extension cord’s rating and use it only in environments and situations it’s rated to be used in. The rating should be visible as a letter or series of letters imprinted onto the cord’s outer insulation.
    • S indicates the cord is intended for general use.
    • T indicates the cord is made from vinyl thermoplastic.
    • O indicates oil resistance.
    • W indicates the cord is rated for outdoor use. NEVER use a cord that does not have the “W” rating outdoors.
    • P indicates parallel wire construction.
    • E indicates the cord is made from TPE, a type of thermoplastic rubber.
    • J indicates the cord features standard 300 voltage insulation.
  • ALWAYS use a Ground Fault Circuit Interrupter (GFCI) outlet when using extension cords outdoors.
    • This type of outlet will help prevent electrical surges, fires, and other would-be disasters when using the cord outdoors.
    • GFCI outlets can usually be identified by the large button underneath the plug-in point, usually red. Newer homes will always have them by law.
    • Even if you live in an older home where they’re not legally required, it’s a good idea to install GFCI outlets indoors and outdoors for safety.
    • While they’re a good idea everywhere, you MUST use GFCI outlets when plugging in extension cords outdoors, or anywhere else where water exposure is a possible risk.
  • ALWAYS check the amperage limits of your appliance and make sure that the extension cord is rated to tolerate those limits (amperage/wattage limits should be listed on the cord’s packaging).
  • NEVER use a broken or damaged extension cord, even if the insulation is only partially torn.
  • NEVER use a grounded (three-pronged) extension cord in an ungrounded (two-pronged) outlet.
    • Especially NEVER try to cut off or otherwise remove a ground (the large third prong underneath the other two on a grounded cord) to make a grounded cord fit an ungrounded outlet.
    • In general, it’s best to use grounded outlets and cords whenever possible.

For a more detailed set of guidelines, please visit this page to learn more.

Quick Answers About Extension Cords:

While following the five guidelines above will empower you to safely use extension cords in most situations, sometimes specific questions and concerns apply that may not be covered by these rules.

With that in mind, let’s take a look at some common concerns when using extension cords and give you a few answers that will make putting safety first even easier for you when it comes to extension cord use:

Is it Safe to Plug Extension Cord into Another?

While startlingly common, doing this poses a serious risk of an electrical surge, injury, and property damage; do NOT daisy-chain extension cords.

There are a few reasons for this. The most important one involved amperage limitations.

Effectively, every power strip, extension cord, and electrical outlet is rated for a certain maximum amperage that it can withstand.

With most everyday use—especially if you follow the third rule above and check your amperage limits—this isn’t a problem, as each individual cord/outlet/etc is unlikely to have this limit exceeded.

However, when you plug multiple extension cords together, this changes the amperage limit of the combined cords and makes it much more likely that the appliance you plug in at the other end will exceed this new limit.

Is it Safe to Plug Extension Cord into Surge Protector?

This one isn’t the biggest no-no on the list, but it’s still a bad idea, mainly because it makes it a lot harder for the surge protector to do its job.

While an extension cord plugged into a surge protector will work, if you ever do experience an actual electrical surge, the added length of the extension cord means the surge protector will experience a delay in stopping the surge.

This delay may be long enough for the heat to build to sufficient levels to start an electrical fire despite the surge protector.

For this reason, please do not plug extension cords into surge protectors.

Is it Safe to Leave Extension Cords Plugged in Outside?

While it’s not the most dangerous thing in the world, you probably shouldn’t be leaving extension cords plugged in at all, but especially not outdoors.

Extension cords are primarily intended for temporary use, such as, say, to power an electrical tool while it’s in use; when you’re all done, you unplug and pack up both the tool and the cord.

Furthermore, even if you’re using an outdoor-rated extension cord (check for the “W,” and do NOT use an indoor-rated cord outdoors, more on that below), leaving it outside all the time subjects it to gradual wear and tear.

Put another way, if you leave an extension cord outside, it might be fine right now, and tomorrow, and the next day…but eventually it is going to break down from continual exposure to the elements, and at that point, you have a potential fire hazard on your hands.

Check out our blog here about what does extension cord gauge mean & does it matter?

Is it Safe to Bury Extension Cords?

Typically, no, it is not safe to bury extension cords.

You may be aware power lines are sometimes buried, and reason that you should be able to do the same with an extension cord.

The problem is that extension cords are not designed to be buried, and if you do not allow them open-air to stay cool, they can overheat and melt their insulation, causing all kinds of very dangerous problems.

If you want to bury a power cord, you need to find cords that are specifically rated for underground use; and even then you’ll probably need professional help installing them.

Is it Safe to Use Extension Cords in the Rain?

Indoor-rated extension cords should NEVER be used outdoors at all, and especially not in the rain.

But what about outdoor-rated cords? Outdoor extension cords do have a water-resistant coating that can withstand a reasonable amount of moisture.

That being said, while some water exposure is okay, there are a few caveats and important safety precautions to consider.

The ends of your extension cord, the plug and the socket, should NEVER be exposed to water. Your electrical outlet should also be sheltered and not exposed to water.

Further, you shouldn’t just leave a cord in the rain indefinitely; while short-term use in wet conditions might be alright, do not leave your cord unattended in the rain.

So if both ends of the extension cord are sheltered from water, and you’ll only be using it for a short time in light rain, you’ll probably be okay.

But exercise all due caution, keep those ends dry, and do not use the cord for any longer than necessary.

Is it Safe to Use Old Extension Cords?

It depends! An older extension cord may still be perfectly safe, or it may be best to replace it. This depends on a few things.

Firstly, check to make sure there is no damage to your cord. If the cord feels loose, or if there is a crack or other damage to the insulation, throw it away and get a new one.

If the cord feels hot to the touch when plugged in, you should also replace it; this is a sign that the cord is being used above its rated limits, or has been damaged by overuse in the past.

Furthermore, if the older cord lacks a ground (the third, large prong under the two top prongs), your safety concerns would be best served by replacing it with a new, grounded cord.

If your old cord passes all these tests (it’s not damaged, doesn’t feel hot in use, and has a ground), then it might still be perfectly safe. If you have any lingering concerns though, it never hurts to replace an old cord just to be on the safe side.

Is it Safe to Tape an Extension Cord?

This depends on what you’re doing with the tape!

If the insulation of your extension cord has broken and you’re using electrical tape to repair the tear, STOP and throw away the extension cord; this is not safe and the broken cord should be discarded and replaced.

But what if your cord is undamaged and you’re just using tape to stick it to a wall, or something like that?

Well, that’s a bit more complicated. In theory, you might be alright, but there are many things to keep in mind here, and it’s very easy to accidentally create an overheating issue (and therefore a fire hazard) where tape and extension cords are involved.

Basically, you’ll want to pay careful attention to the heat limits of the cord, the insulating power of the tape, and other factors, and you might want the advice of an actual expert on this one.

So suffice to say it’s too complicated to give you a satisfying answer within the scope of this article. Just be careful when it comes to taping extension cords, and if you’re unsure, err on the side of caution and don’t do it.

Is it Safe to use Indoor Extension Cords Outside?

Absolutely not! Do not do this; extension cords are rated for different uses for a reason.

The letter “W” usually indicates an outdoor-use-rated extension cord in North America. ONLY use an extension cord outdoors if it has this marking or otherwise indicates that it’s rated to be used outdoors safely.

Indoor-use extension cords simply do not have the added insulation, weatherproofing, etc to handle the outdoors, and subjecting them to outside conditions is practically inviting an electrical fire.

Read our blog here about do extension cord need to be grounded?


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