Best 15, 20, 30, 50 amp & RV Extension Cords

When looking for an extension cord, it is important to pick one that meets your needs. There are several reasons why getting one is beneficial, but the most common is not having easy and close access to an outlet. For example, if you need to set up a few lights in the middle of your backyard, you can use an extension cord to extend the range of the nearest outlet. Before we proceed, it is important to know that you cannot just use any wire. Similar to AWG wires, extension cords have different sizes, lengths, and types.

Extension cords come in several lengths, which you may or may not notice when taking a trip to an electrical supply store. Some available lengths are 15 feet, 20 feet, 25 feet, 30 feet, 50 feet, and 100 feet. Your mind might be telling you to pick the longest length available, but that should not always be the case. A recent study conducted by the United States Consumer Product Safety Commission highlights that extension cords are among the leading causes of fire accidents. The main reason is due to incorrect length and wire size.

With that said, consumers should at least know the basic principles behind extension cords. In this article, you will know some of the important things to consider when looking for the best RV extension cords and the right amperage capacity for your needs. Everything in this article may not be important to you. We conveniently labeled each section for you. You can skip to this section by using your browser’s search functionality, no matter if you’re on the lookout for the best 15, 20, 30 or 50 amp extension cord, or perhaps one for your RV!.

What to look for in an extension cord?

It is safe to assume that each household has at least one extension cord. One might think all extension cords are the same. However, most people do not understand the differences in environmental compatibility, wire gauge, and purpose matter. Consumers need to realize that extension cords are always a temporary solution to a problem. You should avoid using it as a long-term solution in extending your household’s electrical system. If you think you need a long term solution, it is better and safer to contact a licensed electrician for consultation.

Although an extension wire is simply a cord that extends an outlet’s reach, it comes in different forms and sizes. It also comes in several types of plug, such as a twist-lock or a 3-prong. Below are some of the important things you should be looking for in an extension cord.

The wire gauge is important

Extension cords come in different sizes, just like how AWG wires come in several sizes. We classify extension cords into three categories – occasion use or light-duty, medium to frequent use or medium-duty, and rugged use or heavy-duty. We use these terms to refer to the wire’s size. It indicates whether a particular cord size will work safely for heavy, continuous use, such as heaters, power tools, and computers. If it is your first time looking at gauge numbers, it might confuse you. It is important to know that the number is inversely proportional to the wire’s diameter, which means a 10-gauge wire is thicker than a 16-gauge wire. The former can handle high amp capacity while the latter cannot. Thicker wires can handle more electricity at any given time, which means it is suitable for heavy-duty tools that demand high power.

At this point, you now have an idea of the importance of a wire gauge. So what happens if you pick or use the wrong size? The wire will burn if you use an incorrect wire size. It can also cause damage to your equipment or start a fire at worst. It is advisable to know which size to use to prevent bad things from happening. People who are not aware of the importance of size usually use smaller sizes because they are cheap, thinking it would not make any difference. Undersizing it may only cause you more in the long run. Opting for a larger wire is the best way to go, even if it is more than the recommended size. The only negative it may have is on your budget, which will cost more upfront.

Choosing between indoor or outdoor cords

You can use extension cords indoors or outdoors. The latter uses a tough rubber, vinyl, or plastic cover for maximum durability. In most cases, an indoor extension cord is cheaper, which is why people prefer to buy and use it outdoors. It could lead to electrocution, failure, overheating, or fire. What you need to do first is to know where you will be using the extension cord. If you have the budget, immediately go for an outdoor extension cord so you can use it indoors and outdoors. It is going to cost more, but its use case is more flexible than the other one.

Frequency of use

There are three main categories for how frequently you use a cord. Occasional use cords are usually thin and lightweight. They come in 16-gauge or 18-gauge wires that can easily handle 12 amps, 13 amps, or even 18 amps. Some light-duty indoor appliances examples are portable fans, electric hedge trimmers, vacuum cleaners, and holiday lights.

In the case of appliances and tools you frequently use, such as television sets, power drills, electric chainsaws, snowblowers, and table saws, you should consider getting a 14-gauge cord. It is the ideal size for frequent or medium-duty applications.

Lastly, for heavy-duty and extra heavy-duty applications, we recommend getting at least a 12-gauge cord. Any size thicker than a 12-gauge should do well too. The heavier weight of rugged cords allows them to withstand extreme weather conditions. They are also suitable for very high-amperage tools, such as air compressors and generators.

Looking at the wire’s jacket, you will see a designation letter. Below are some definitions to know.

  • S – The cord is flexible, which you can use for general use.
  • W – The cord is for outdoor use.
  • J – The cord has a standard 300 V insulation. Otherwise, it has a thicker 600 V insulation.
  • O – The cord is oil-resistant.
  • P – It has a parallel wire construction, which you can use for household extension cords.
  • T – The jacket uses vinyl thermoplastic.
  • E – The jacket uses thermoplastic elastomer rubber (TPE).

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How many amps can you run through an extension cord?

The number of amps you can run through an extension cord depends on the AWG size you are using. Like an electrical wire, extension cords also follow a size chart, which determines the number of amps a particular size can support.

Let us look into the size chart below. A 6-gauge is the minimum safe choice if you have a supply power of 50 amps. On the other hand, you can use a 10-gauge copper wire at 167°F if you have a supply of 35 amps. Use the table if you need help in determining the ideal AWG size for your needs. If you are a camper going on a trip, you may want to opt for thicker sizes as they can withstand the outdoors.


Aside from the ampacity requirement and ambient temperature rating, knowing if the conductor is aluminum or copper is important too. Copper can carry more amps than aluminum at the same AWG size. It means if you have a 10-gauge aluminum wire and a 10-gauge copper wire, the latter will likely support more amps than the former. Moreover, wire gauges can carry more amps at a higher ambient temperature rating. If you look at the table above, a 6-gauge wire with an ambient temperature rating of 167°F can only carry up to 65 amps, whereas the same gauge wire with a higher ambient temperature rating of 194°F can carry up to 75 amps.

As discussed in the previous section, the AWG size has an inverse relationship to the wire’s diameter. For example, a 6-gauge wire has a diameter of 4.115 mm, whereas a 10-gauge wire has a diameter of 2.588 mm. It shows that the higher the AWG number, the thinner the diameter of the wire.

These factors make it a challenge to pick the correct AWG size for your requirements. Always remember that choosing a size thicker than the recommended size is not a problem.

15 amps

For 15 amps, you need at least a 14-gauge copper wire at an ambient temperature rating of 194°F or lower, or a 12-gauge aluminum wire at an ambient temperature rating of 167°F. Heating appliances and a few tools are a few things that utilize around 15 amps.

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20 amps

Twenty amps of power would need at least a 12-gauge aluminum wire at an ambient temperature rating of 167°F. If you prefer using a copper wire, you may do so at ambient temperature ratings of 140°F, 167°F, and 194°F. Typical appliances that consume around 20 amps are generators, power tools, vacuums, lawn equipment, chargers, and heaters.

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30 amps

For 30 amps of power, you need at least a 10-gauge aluminum wire at an ambient temperature rating of 167°F. If you prefer to use copper wire, you can opt for an 8-gauge copper wire at ambient temperature ratings of 140°F, 167°F, and 194°F. 30 amp cables are usually for RVs, trailers, campers, and vehicles.

50 amps

Fifty amps of power need at least a 6-gauge aluminum wire at an ambient temperature rating of 167°F or an 8-gauge copper wire at an ambient temperature rating of 167°F. You can also use any AWG size that is thicker than a 6-gauge wire. You can use a 50 amps cable in several applications, such as trailers, vehicles, campers, and RVs.

How far can you run a 30 amp cord to a camper?

In most cases, any length between 25 feet to 50 feet should do you fine. Most RVs come with a standard cable length of 25 feet. You can go as long as 50 feet, but always keep in mind that an increase in an extension cord’s length also increases electrical resistance, which then generates more heat.

Can you connect two 30 amp cords together?

Daisy-chaining is the connection of two or more extension cords to cover a longer coverage. Although you can connect two 30 amp cords together, you should not do it. Connecting two or more cords could cause the power strip or power outlet to overload, leading to a meltdown or fire.

What size wire do I need for a 50 amp plug?

For a 50 amps plug, you can use an 8-gauge copper wire or a 6-gauge aluminum wire. The copper wire and aluminum wire should both have an ambient temperature rating of 167°F or lower.

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Can I plug my 30 amp into a 50 amp?

No, you cannot plug a 30 amp into a 50 amp, or vice versa. The main reason is the physical differences between them. However, there are also differences in the electricity they provide.

A 30 amp plug usually features a 3-prong plug with a 120V hot wire. It carries current along with a neutral prong and a ground wire. RVs with low power requirements usually utilize a 30 amps system. On the other hand, a 50 amp plug usually has a 4-prong plug, which can supply two 50 amps 120V lines. Large RVs with an air conditioner and a few appliances often need a 50 amp system.

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