What Are the Best Heavy-Duty Extension Cords for Outdoor Use?

August 23, 2023

Extension cords are extremely useful when there is no convenient electrical outlet nearby. Under certain conditions, it is also important that the heavy-duty extension cords are properly rated for the application they are being used for. Outdoor extension cords also need specific ratings to ensure they are safe when exposed to the elements. When choosing the best heavy-duty extension cord for outdoor use, you must ensure it will do the job. Working with any cabling in an outdoor environment requires that cords have the right wattage rating, are rated for outdoor use, offer sufficient protection from the elements, and otherwise are manufactured to work safely for the application and under the conditions they’re exposed to.

Choosing the Best Heavy-Duty Extension Cord

Understanding what factors make a cord the best choice for a certain application is essential to safely getting any commercial job done. Factors include gauge, wattage, certification, and energy demand of multiple devices working off a single extension cord. Before looking at what makes the best heavy-duty outdoor extension cord, it’s important to know what to look for when choosing.

Choosing the Best Gauge

Extension cords are made up of strands of copper wiring wrapped in plastic insulation, which makes them more flexible. Generally, the thicker the gauge, the higher the cord’s capacity for transporting electricity. Generally, a 14-gauge heavy-duty outdoor extension cord works well for less powerful devices like electric hedge trimmers or leaf blowers, while for larger devices, a 12 or 10-gauge cord would work better.

Extension cord gauge can be accurately identified by following these steps: 

  • Locate markings on cord: These are normally accompanied by the number of conducting wires, so one with a “12/3” marking refers to a 12-gauge wire with three conductors.
  • Consult gauge chart: The lower the gauge, the thicker the wire, the more current it can carry, and the lower the resistance, with the opposite also true.
  • Measure cord length: The longer the cord, the higher the electrical resistance, so to ensure optimal performance, it’s best to avoid connecting multiple extension cords.
  • Assess amperage: Extension cords come with amperage ratings, with heavier electrical loads requiring cords with higher ratings; the cord’s amperage must be compatible with the electrical device attached to it.

The gauge is determined by American wire gauge (AWG) standards, and the best heavy-duty extension cords for outdoor use are between 10 and 14 gauge, with 10, 12, and 14 being the safest. Lengths generally measure 100 feet (30.48 meters), 50 feet (15.24 meters), and 25 feet (7.62 meters) but there is a wide variety of lengths available out there as well as custom solutions for professional or commercial applications..

Three Prong Plugs

The best heavy-duty extension cords use three rather than two prongs for their plugs. With a two-prong cord, one prong carries the current from the outlet to where the electricity is needed, while the second is neutral. While two-prong cords are more versatile, as they can be used in both two- and three-prong outlets, three-prong plugs have a grounding wire that makes them safer.

Three-prong plugs help prevent:

  • Damage to electrical devices from power surges protected by the grounding prong.
  • Electrocution by redirecting any excess power to the grounding prong.
  • Fire caused by a spark resulting from surplus electricity due to a power surge better contained by a grounding prong.

In certain cases, outdated outlets may only have two prongs, so greater care should be taken to ensure electrical safety.

Best Heavy-Duty Extension Cord for Outdoor Use  

There are numerous differences between the best heavy-duty extension cords for indoor or outdoor use. Those rated for outdoor applications will utilize more robust insulation materials that can withstand ultraviolet light, temperature extremes, and damp conditions. For certain applications, the cable must also resist chemical exposure and weathering.

While heavy-duty outdoor extension cords can safely be used indoors, one rated for indoor use should not be used outside. Choosing the best extension cord for outdoor conditions will lower the risk of electrical shock or fire, so it should be done carefully. A heavy-duty outdoor extension cord might require a higher gauge wire and be made from weatherproof materials, among other characteristics.


The best heavy-duty extension cords for indoor use don’t need to handle the weather. Yet, depending on the application and climate, a heavy-duty outdoor extension cord must be sufficiently protected against various weather conditions, including rain, snow, sunshine, and wind. Depending on the application and terrain, abrasion-resistant cabling may also be necessary.

Extension cords meant for outdoor uses should have thick, heavy-duty protective jackets. Outdoor extension cords should also have a watertight plug that’s well-sealed against moisture that could dangerously infiltrate the plug. Generally, a heavy-duty outdoor extension cord will be made from a tough material like vinyl graded for outdoor use.

Understanding Cord Categories

Extension cords can be grouped into three comprehensive categories depending on whether they’re to be used frequently or occasionally and whether their duties will require them to be heavy-duty. Outdoor extension cord classifications are additionally designated by a W on their packaging, with the primary difference being the amount of insulation used to protect the wiring. Heavy-duty outdoor extension cords also generally come in bright orange or dark green and are made with plastic, rubber, or vinyl covers.

Other letters denote the applications for which cabling can be used, which include: 

  • E indicates a cord jacket made from thermoplastic elastomer (TPE), one of the most durable materials commonly used for heavy-duty extension cords.
  • J stands for “junior” and shows the cord offers standard insulation to withstand about 300 volts. In contrast, if the cord isn’t designated as such, it’s a heavier-duty cable with insulation to withstand 600 volts.
  • O means the cord is resistant to oil, so it can be used when oil-based fuels or fertilizers come in contact with the cabling.
  • P is for household use, featuring construction with parallel wiring, and it’s commonly used for air conditioners, along with standard household extension cords.
  • S is for all-purpose use; if no other designating letters exist, they shouldn’t be used outdoors. These cords are generally unacceptable for heavy-duty applications.
  • T indicates a cord jacket made from vinyl thermoplastics.

It’s important to check the cord’s packaging, or even the cord itself, for these letter designations to choose the best heavy-duty extension cord for the application. This should be the case for both heavy-duty extension cords and those meant for indoor use.

Contact the Experts at Alert Reel Manufacturing 

Alert Reel Manufacturing is proud to be a leading manufacturer of heavy-duty extension cords, cord reels, cord management, and task lighting for commercial settings. With our advanced in-house capabilities, we can help you find custom solutions and provide high-quality products for commercial customers. To learn more about the best heavy-duty extension cords for your commercial application, please contact the experts at Alert Reel Manufacturing today.