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Extension Cord Safety: What You Should Know

extension cords

Reduce Your Risk with Extension Cord Safety

Using an extension cord is a common way to supply power to an electrical device that is not close to an electrical outlet. They are also convenient for yard tools, mobile electronics, and small appliances. While many homeowners do not give their collection of extension cords a second thought, extension cord safety is paramount to avoiding potential electrical fires.


According to the Electrical Safety Foundation, disregarding extension cord safety leads to more than 3,000 extension cord fires each year. That may not seem like a high number, but it is a massive ordeal for those who experience them. Luckily, with proper extension cord safety, you can reduce the risk of a catastrophic event.


As the leading Gilroy electrician in Santa Clara County, CA, Watson’s Charging Stations & Electric strive to educate our customers and community on electrical safety. That is why we put together this quick guide to extension cord safety—read on to learn more.


Extension Cord Safety Starts at the Store

When you walk through your local hardware store, it may seem like all of the available extension cords are interchangeable, if not practically the same. In reality, various kinds of extension cords with different lengths, wire gauges, amperage limits, and designations impact how they should be used. You should be able to find all of this information on a tag attached to the cord.


You want to ensure you are using the right cord for the job. For example, you would not want to use an indoor cable without weather protection to power your Christmas lights, and you would be only one weather event from a short circuit, electrical fire, or damage to your holiday lights.


Extension Cord Designations

Every extension cord has a designation that helps shoppers know how the cord is meant to be used. You will find a single letter that reveals its designation:

  • S: General use

  • W: Outdoor use

  • J: Standard 300-volt insulation

  • T: Made from vinyl thermoplastic (lightweight and offers low-temperature resistance)

  • P: Parallel Wire Construction (used in air conditioners)

  • O: Oil-resistant

  • E: Made from TPE (resists oil, water, chemicals, and acid: can handle extreme weather)


Many electrical cords can be used outside their designations, while others cannot. For example, there is nothing necessarily wrong with using a TPE extension cord for an indoor appliance, but you would never use a general-use cord in an area that comes in contact with chemicals. Moreover, you will overpay for a more durable cord than what the project needs.


Using a cord with the wrong designation could lead to cord damage. A vinyl thermoplastic cord, for example, does not hold up under high temperatures. Using this kind of extension cord in a hot furnace room could lead to the insulation melting and the internal wires being damaged. Any time wires are exposed, you run the risk of an extension cord fire hazard or someone getting shocked.


Extension Cord Gauges

Cord gauge refers to the thickness of the cord’s wires. Lower-gauge extension cords have thicker wires and a higher capacity. A 10-gauge extension cord is thicker than a 16-gauge cord and thus is able to accommodate larger power loads. For a real-life example, compare the cord on your blender to the one going to your outdoor air conditioning unit. The AC unit requires more power and has a thicker cord to show it.



An amperage rating shows you how much power the cord can handle. You want an extension cord with the same or preferably higher than the device it is being used to power. It is safe to use an 18-amp extension cord to power a 10-amp appliance. The reverse (using a 10-amp cord with an 18-amp device) is unsafe.



Walk the aisle of any hardware store, and you’ll see extension cords of all lengths. The longer a cord is, the more resistance it has. That means it needs to be able to handle more power to power a device consistently. For example, a 25-foot 14-gauge extension cord can typically handle 14-15 amps. If you increase the length of the cord to 100 feet, the cord would need to be 12-gauge (thicker) to handle the same load. A 150-foot cord would need to be 10-gauge to do the same.


Use Extension Cords Properly

Once you have the right extension cord for the job, you must make sure you use it as intended. Several basic tips work for all extension cords, regardless of their designation, amperage, length, or gauge:

  • Avoid using multiple extension cords together.

  • Never attach extension cords to surfaces with staples or nails.

  • Never remove an extension cord’s grounding pin to make it fit in a two-prong outlet.

  • Only use outdoor-rated extension cords outside.

  • Stop using and replace extension cords that feel hot to the touch.

  • Space heaters should never be plugged into an extension cord.

  • Inspect extension cords for signs of damage before use.

  • Ensure the extension cords you purchase are labeled by an independent laboratory (like the Underwriters Laboratories).

  • Unplug extension cords when not in use.

  • Look for an extension cord with GFCI for damp or wet areas.

Extension Cord Safety Care

Maintaining your extension cords is critical to avoiding future hazards, which is why you want to give them proper care at all times.

  • Unplug an extension cord by its plug, not the cord.

  • Store unused extension cords indoors in a safe location.

  • Throw away damaged cords.

  • Unplug extension cords when they are not in use.


Find a Permanent Solution

Extension cords are meant to be used as a temporary wiring solution. That means you should not rely on extension cords to power everyday appliances like your refrigerator or entertainment center. In cases when these kinds of electronics are not close enough to an outlet, it might be time to add new receptacles to your home. Sometimes extension cord safety means not using an extension cord at all.


Installing a new outlet is not always something you want to attempt yourself. A residential electrician near Gilroy, CA, can help ensure you get access to power where you need it. You can rest assured that a licensed electrician in Santa Clara County can complete your job safely and efficiently.


If you are in the Santa Clara Valley and have an electrical project in mind, call Watson’s Charging Stations & Electric for a free consultation.