Lawn mower extension lead. Does The Length Of An Extension Cord Affect The Power

Does The Length Of An Extension Cord Affect The Power?

An electrical extension cord is an ideal way to elongate multiple circuits to spaces you are operating on, away from static outlets. But why do we need one in the first place? It might be because of extended electrical operations. Besides, sometimes you only require a small cord to plug in your appliances, tools, and equipment and conclude the assignment.

Having said that, we have been a part of a situation wherein we have had to rope several extension cords to reach a specific area. In this case, how many cords can you thread together and still not compromise on the amount of power produced? Numerous factors determine an extension cord’s safety, potency, and usability. Both outdoor and indoor extension cords vary in size, power usage, and many more.

How are extension cords used?

Outdoor electrical cords are a significant part of the backyard landscape, energizing anything from hedge trimmers to kitchen mixers, power saws, and even lawnmowers. On the other hand, the indoor ones are utilized for temporary power requirements from attics to basements. Since these equipment and tools comprise various power ratings, they are manufactured to maneuver many forms and types of temporary operating needs.

However, not every extension cord is designed equal. An inadequately sized cord can lead to the burning of motors and tools if granted more running duration. over, such a situation can result in overheating or otherwise hazardous circumstances.

How can you avoid these issues?

First, it helps to understand how much current (in amps or amperes) every electrical tool needs. Tools such as mowers and saws use relatively higher amps. Consequently, cords associated with considerable electrical loads must be utilized to operate them. In addition, their respective manuals specify extension cord needs for proper equipment operation. You can even check the amperage ratings on the tool.

However, how does a user know the amount of electrical burden the extension cord will manipulate? Well, there are a couple of factors, like cord thickness and length. The thicker its copper wire, the more electricity the wire can accommodate. But, since mediated power declines over specific sizes, a more extended cord needs a ponderous wire to produce a full current rating.

In addition, there are other factors to examine as well.

  • How far is the electrical outlet from the circuit breaker you’re connecting to?
  • What’s the size of the circuit breaker you’re connected to?
  • What’s the size of your wiring that feeds the outlet?

Voltage Drop

Often, a user does not require the cord size compared to the run’s length. They simply tend to get any or all extension cord sizes and place them in conjunction. Meanwhile, have you come to terms with resistance caused by extended runs of wire? While copper wise is an excellent conductor, it promotes resistance that leads to heat. Heat damages not only the extension cord but also the connected appliances. Eventually, the voltage drops and heats the inbuilt motor of your tools. In this case, you could utilize a power cord to multiply the number of electrical outlets through a single source.

On the other hand, when you operate a tool, such as a drill machine, and it runs slower than usual, consider it a warning sign. While some machines come with warning lights, others must be dealt with by thoroughly checking their manuals. often, owning the best extension cord to reach the space you intend to operate can resolve a situation or two. However, they should never be used in extended runs and for heavy-load machinery types, such as compressors and sump pumps.

About Resistance

Apart from voltage drops, resistance can lead to heat production. The longer you use the cord, the more heat your wire will produce. Suppose you throw a long extension through the yard or underneath the rug. In that case, the cord can get hot enough to set alight. The possibility of this occurring escalates if the cord has any damage in its length.

Extended Cords Are Likely to Get Damaged

In its journey from the plug to your appliance or equipment, a long cord has to cross various places where it can invite damage. Such areas consist of walkways, driveways, basements, underneath doors, and crawl spaces. In addition, extension cords that pass through a window down towards the ground can also promote damage. Even small gouges and nicks that expose the wires are dangerous. As a result, choose a cord wisely.

Extension Cord Usage Chart

Extension Cord Length (Feet) Maximum Amperage
100 5
100 15
75 5
75 10
75 15
50 5
50 10
50 15
25 10
25 13
25 15

The bottom line

While the length of the cord does matter, it’s essential to understand that as the current flows, it loses some voltage. This can lead to the drill running slower, lights being dimmer, etc. What’s essential is the cord’s length, the gauge of the wire, and the current draw of what you’re plugging into the extension cord.

Extension Cord Safety: A Comprehensive Guide

We all know the basics of using an extension cord. But do you know about extension cord safety? Without taking the right safety precautions, using an extension cord can put you, and your home, at risk of an electrical accident. If you’re planning on using extension cords to add to your outdoor lighting or simply need to extend an outlet, you must also keep in mind extension cord safety.

To help achieve this, Roman Electric has assembled a comprehensive guide. Follow our tips below for your Milwaukee home!

Avoid Using Damaged Extension Cords

Before using an extension cord, you’ll want to check its condition. Extension cords can receive a fair bit of damage throughout their lifespan. Exposed cords, frayed wires, or cracked plugs can cause an extension cord’s electrical flow to become uneven. This can cause a short circuit, which can trip the circuit breaker and potentially cause shock.

Don’t risk using a damaged extension cord. Check each cord’s condition before use and discard any cords with noticeable damages.

See What Conditions Your Extension Cord is Suitable For

Damages aren’t the only thing you should check your extension cord for. You must also check to see if it is suited for indoor or outdoor use.

On the cord you may find several different letter symbols. Each letter indicates a quality about the extension cord, including whether or not it can handle outdoor weather conditions. Below are some common letters you’ll find on an extension cord, and their associated meaning.

  • S – Suited for General Usage
  • W – Suited for Outdoor Usage
  • J – Cord has 300V Insulation
  • T – Cord is Made from Vinyl Thermoplastic
  • O – Cord has Oil Resistance

After examining the letters, you’ll need to also look at the amperage rating. This determines how much capacity an extension cord can handle. As a rule, the higher the amperage rating, the higher capacity of the extension cord. Here are some examples:

  • 1-13 Amperage Rating – Light Duty, suitable for lamps, desk fans, and other small appliances.
  • 14-15 Amperage Rating – Medium Duty, suitable for power drills, lawn mowers, and hedge trimmers.
  • 16-20 Amperage Rating – Heavy Duty, suitable for power saws, space heaters, and air compressors.

The Truth About Coiled Extension Cords?

Note: Be aware that the longer the extension cord, the less power it can distribute. Therefore, use a cord only as long as you need.

Match Extension Cord Prongs with The Outlet

An extension cord’s plug can either have two or three prongs. If the plug has two prongs, then it can fit in either a two or three-prong outlet. Two-prongs lack a connection to the ground. Ground is used to safely transfer electricity and help prevent electrical shock. Keep this in mind when using a two-prong extension cord.

If the extension cord’s plug has three prongs, then it can only be used with a three-prong outlet. The third prong acts as a ground and is safer to use than two-prong outlets. However, they cannot fit in two-prong outlets.

Note: Do NOT attempt to cut off the third prong of an extension cord to use with a two-prong outlet. This can create unstable electrical flow and may damage the connected appliance or cause severe shock.

Avoid Connecting Multiple Extension Cords

Extension cords should never be paired together. Combining extension cords can lead to excessive voltage, as electrical resistance is lowered the more cords are combined. This can lead to an electrical overload, which trips your circuit breaker.

lawn, mower, extension, lead, does, length

Speaking of tripping, multiple extension cords can also be a fall hazard. Avoid tripping your circuit breaker – and yourself by only using one extension cord at a time. Be sure to run them along walls and away from heavy traffic areas as well.

Do Not Substitute Extension Cords for Permanent Wiring

Above all, you must always remember that extension cords are a temporary solution. They do not possess the capacity to be a permanent replacement for an electrical outlet. If you find yourself heavily relying on extension cords, you may require more outlets in your home. Contact Roman Electric for affordable outlet installation services.

Never use an extension cord without first reading our comprehensive guide! And remember to only use extension cords are a temporary solution for an outlet. If you are in need of additional electrical outlets in your Milwaukee home, contact Roman Electric today. Call us at 414-369-3798 for affordable outlet installation services.

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Extension Cord Size Chart – Understanding Wire Gauge and Amps

After searching the Internet recently, we realized people needed a definitive extension cord size chart. Understanding wire gauge proves difficult in some situations. This chart breaks down how both the wire gauge and length of an extension cord affect its ability to convey power to a corded tool. Running a 15-amp tool? How about a full 20-amp tool? We can help you understand what length and gauge extension cord gets you and keeps you up and running.

Extension Cord Size Chart – Wire Gauge vs Length

That’s right, we’re giving you the chart right up front without making you read through paragraphs of text. If you want to know more, like what is AWG or American Wire Gauge, see below. However, if you simply want to know what gauge extension cord you need to support a particular amount of amps, or how long an extension cord you can run without losing power, here you go. Getting a firm grasp on understanding wire gauge and amps and how they interrelate can protect your tools and keep you safe.

We broke our charts down by extension cord length since that’s where most people start when looking for the right gauge cord:

100-foot Extension Cords

If you want to run a 100-foot long extension cord, you have to take into account the fact that you’re essentially creating a huge resistor. With that in mind, you typically don’t see 100-foot cords exceeding 15-amp (15A) capacity.

Current DrawMinimum Wire GaugeVoltage Drop
20A 10-gauge 4.00%
15A 12-gauge 5.00%
12A 12-gauge 4.00%
10A 12-gauge 3.33%

Yields a 5% voltage drop—the maximum allowed in our calculations. Consider using the next size up for anything that is at or near 5% or—even better—opting for a shorter cord whenever possible.

50-foot Extension Cords

Current DrawMinimum Wire GaugeVoltage Drop
20A 12-gauge 3.33%
15A 14-gauge 3.88%
12A 14-gauge 3.10%
10A 14-gauge 2.58%

25-foot Extension Cords

Current DrawMinimum Wire GaugeVoltage Drop
20A 14-gauge 2.58%
15A 14-gauge 1.94%
12A 14-gauge 1.55%
10A 14-gauge 1.29%

See below for some recommendations on extension cords which should match the above requirements.

Assumptions for Sizing Extension Cord Length

For our extension cord size chart calculations, we assumed 120V single phase with a power factor of 1. We also utilized the 2014 NEC Chapter 9, Table 9 numbers for impedance and voltage drop calculations.

We also allowed for up to a 5% voltage drop—which some people might consider too high. With that being the case, only one of our recommendations hit that level, the 100-foot 12-gauge extension cord with a full 15A draw. This might be an unusual application for some, but we felt it represented a great scenario. It helps you understand what happens when using a 100-foot extension cord on a tool with a high current draw.

Why Understanding Wire Gauge and Amps Matters

Everyone on a job site or remodel has some experience with running extension cords. For larger tools that require them, it’s not enough to simply tap into the temp power pole or a nearby outlet. You have to ensure that if your tool requires 15 amps, it gets 15 amps. Use an extension cord that doesn’t carry the correct thickness (gauge) wire and you “starve” your tool.

But, you also do something worse. First, you can tax the tool motor—causing it to work harder to draw the energy it needs to run. Think of this like trying to breathe through a straw. If that straw isn’t large enough to deliver air, you struggle to breathe. That’s your tool on an improperly-sized extension cord.

Secondly, you potentially create a dangerous situation. An undersized extension cable will heat up over time. Use it in that state for too long, and the wire insulation could melt. This particularly holds true if you keep the wire in a coil, which creates resistance and a magnetic field that heats up.

Some Helpful Do’s and Don’ts


  • Understand how much current you need to draw for your tool or appliance
  • Properly size the wire gauge to the length and current draw required
  • Keep your cables as short as possible for higher current tools
  • Unroll extension cords fully so they aren’t coiled during use


  • Use cables not properly rated for your tool and the length of cord
  • Keep your extension cords coiled during use
  • Use a cord that lacks a ground plug (either missing or broken)
  • Run multiple high-current tools off a single cord or circuit
  • Use a long extension cable if you have a short one handy

Hopefully, you found our extension cord size chart helpful and direct to the point. Understanding wire gauge and amps and how to properly size your cords for the tool and distance can make your tools last longer and run more optimally. You may also want to see our article on what kind of extension cord do I need for even more info.

Clint DeBoer

When he’s not playing with the latest power tool, Clint DeBoer enjoys life as a husband, father, and avid reader—especially the Bible. He loves Jesus, has a degree in recording engineering, and has been involved in multimedia and/or online publishing in one form or another since 1992.

How to wind extension cords so they don’t tangle

Clint’s career has covered nearly the entire realm of audio and video production. After graduating at the top of his class with an Associates Degree in Recording Engineering, he began working for the famed Soundelux studios in 1994, one of the largest post-production companies specializing in audio for feature films television. Working on a myriad of feature films, Clint honed his skills as a dialogue editor, foley editor, and sound designer. Years later, he moved into the expanding area of video editing, where he served as the company’s senior AVID video editor for three years.

Working for such clients as Universal Pictures, Hollywood Pictures, Paramount Home Entertainment, NASA, Universal Studios, Planet Hollywood, SEGA, NASCAR, and others, Clint DeBoer dealt extensively with client management as well as film video editing, color correction, and digital video MPEG compression. He also carries several THX certifications (Technician I and II, THX Video), and is ISF Level II Certified.

After founding the CD Media, Inc. publishing company in 1996, he went on to help start or grow several successful online publications, including Audioholics (as Editor-in-Chief for 12 years), Audiogurus, and AV Gadgets. In 2008, Clint founded Pro Tool Reviews followed by the landscape and outdoor power equipment-focused OPE Reviews in 2017. He also heads up the Pro Tool Innovation Awards, an annual awards program honoring innovative tools and accessories across the trades.

Crediting God and his excellent staff for the success of what is now the largest power tool review publication in the industry, Clint DeBoer hopes to see continued growth for the company as it rapidly expands its reach. Pro Tool Reviews critically reviews hundreds of hand tools, power tools, and accessories each year to help inform users about the best and newest products in the industry. Reaching everyone from the construction industry professional and tradesman to the serious DIYer, Pro Tool Reviews helps tool consumers shop better, work smarter, and stay aware of what tools and products can help put them at the top of their game.

The Best Extension Cords for Outdoor Use: How to Choose Safely

Choosing the best outdoor extension cord requires knowledge and care. There are a few things you need to consider, such as the weatherproofing, the type and condition of the extension cord, and the gauge of the wire.

When you’re working outdoors, you need to have the right extension cord to get the job done safely. Not all extension cords are created equal. some are designed for indoor use only, while others are made for outdoor conditions. In this blog post, we will discuss all of those factors so you can make an informed decision about which extension cord is right for you.

How Do I Know If My Extension Cord Is Safe For Outdoor Use?

Extension cords are a necessary evil. they’re often needed to assist power tools or appliances, but can be dangerous if not used correctly. There are a few things you need to look for when choosing an extension cord for outdoor use.


Make sure the cord is made of weatherproof materials so it doesn’t get damaged in bad weather. An extension cord that is weatherproof will be protected against water, snow, mud, and will also be safe from the threat of abrasion caused by rough terrain.

The extension cord should have a thick, heavy-duty jacket to protect it from damage. Additionally, the plug should have a watertight seal to keep out moisture and prevent electrical shock. Outdoor extension cords have stronger insulation than indoor cables and will be made from a material like vinyl. All LifeSupplyUSA extension cords are manufactured with a thick, vinyl jacket rated for outdoor use.

lawn, mower, extension, lead, does, length

Finally, check the label to make sure the extension cord is rated for outdoor use. You can tell if the cord is rated for outdoor use if the label says Outdoor Use or uses the letter indicator W.- not to be confused with O. A letter grade of W stands for weather-resistant and is meant for outdoor use, O on the other hand, simply means that it is oil-resistant. Although, an extension cord that is oil-resistant is typically suited for outdoor use as well, check the label.


Some cords are suitable for both indoor and outdoor use, including those manufactured by LifeSupplyUSA. These cords are rated SJTW, which means it is suitable for indoor and general use (S), the insulation is a standard 300-volts (J), it is made of a vinyl thermoplastic material (T), and it is suitable for outdoor use (W).

How To Spot Extension Cord Hazards

With all this in mind, please also note that an extension cord is never safe for use if the cable:

Indoor extension cords should never be used outdoors because do not have the proper insulation or protection against moisture. If you use an indoor cord outside, the following dangers are possible:

  • The cord could short out, causing a fire.
  • The insulation on the wires might melt, which could lead to electrical shock.
  • The plastic coverings on the plug might melt or crack, exposing the metal contacts and resulting in an electrical shock.

Additionally, extension cords should never be used to plug in appliances like air conditioners or refrigerators. These large appliances require a lot of power, and using an extension cord can overload the circuit and cause a fire. No extension cord is made for constant 24-hour use, indoors or outdoors. Extension cords are meant to temporarily assist the transfer of power from an electrical outlet that cannot be reached. When not in use, they should always be unplugged.

Which Gauge is Better For Outdoor Use?

When choosing an extension cord for outdoor use, you might be wondering what the difference between a 16-gauge and 12-gauge extension cord is. The answer is that the thicker the gauge of wire, the more power it can handle. A 16-gauge extension cord is good for up to 13 amps, while a 12-gauge extension cord can handle up to 20 amps. If you’re using an extension cord for a high-powered appliance, like a lawnmower or weed eater, you’ll need one with a thicker gauge wire.

AWG Chart

You can refer to this chart on the left for the best gauges (AWG) suitable for various appliances. In this case, a 16-gauge cord is not the best option, favoring low-powered indoor appliances. 14-gauge is a good option for outdoor use on small outdoor appliances like leafblowers, while a 12 or 10-gauge is used for heavy-duty/high-powered appliances or consistent use outside.

The safest gauge options for any outdoor use of extension cords are 14, 12, and 10. If you are using something like a chainsaw, opt for a 12 or a 10 gauge cable.

LifeSupplyUSA Extension Cords for Outdoor Use

If you’re using extension cords outdoors on a regular basis, it might be worth upgrading to a LifeSupplyUSA extension cord. LifeSupplyUSA has extension cords available in lengths of 3 feet up to 200 feet for both indoor and outdoor use (among those including the most popular lengths such as 25, 50, and 75 feet.) In addition to being able to find any size, you can order the desired size in any gauge you need from 10 to 16!

All LifeSupplyUSA extension cords are rated for outdoor use. If you’re interested in a high-quality outdoor extension cord, you can start shopping our catalog here!

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