Extension cords play a vital role in almost everyone’s life. Not all the time an outlet is close enough to access. In this case, you will need an extension cord from a nearby outlet to your location. Many times it has made it easy for people to plug-in. It enables people to recharge a device, supply power to an appliance, or provide light. However, just like AWG wires, the extension cord comes in different forms, types, and sizes.
If you have ever been to an electrical supply store, you will notice extension cords come in different lengths and sizes. The most common length are 25 ft, 50 ft, 100 ft, and 200 ft. In a recent study by the US Consumer Product Safety Commission, extension cords are among the most dangerous electrical products for home use. The main reason for it being dangerous is because of incorrect size and use. With that said, people need to know how to prevent extension cords from failing.
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Electrical Wire Size Chart
Like an electrical wire, extension cords also have a size chart, which determines how many amps a particular AWG wire can handle. This is the only extension cord gauge chart you will need!
The size chart below indicates that a 12-gauge aluminum wire is a safe choice for your 220V 20 amps at 167°F needs. Similarly, you can use a 14-gauge copper wire for a 220V 20 amps at 167°F. If you are looking for an extension cord for your appliances, such as a washing machine, refrigerator, or television, you can use the chart below as a guide.
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The AWG wire for a certain ampacity depends on a few factors, such as the conductive material and the ambient temperature rating. It is important to know the conductive material you plan to use. When using an aluminum wire, you will have to refer to the aluminum column. If you are using a copper wire, you must refer to the copper column. For the ambient temperature rating, there are a few of these, so keep that in mind.
Copper can carry more ampacity than aluminum at the same AWG. In other words, an 8-gauge copper wire can support more ampacity than an 8-gauge aluminum wire. Having a higher ampacity means it can allow more current to flow at any given time. Wire gauges with a high ambient temperature rating can carry high ampacity. It explains why a 12-gauge copper wire with an ambient temperature of 140°F is compatible with 20 amps, whereas the same wire at a higher ambient temperature of 194°F can carry up to 25 amps.
The outlined factors above make it tricky to choose the correct gauge wire size. Always remember that it is fine to pick a bigger gauge than the recommended size. However, never choose a gauge size smaller than the recommended size.
What gauge extension cord should I use?
Getting the correct gauge for your extension cord is very important. Choosing a smaller one can ruin your tool or even start a fire. In most cases, a common small hand-held electrical tool can operate without any danger or problems with a 16-gauge extension cord that is about 100 feet long. Reading through this section will guide you in determining the correct size to use.
Obtaining the amperage rating
The first thing to do in sizing an extension cord is to obtain the motor amperage from the tool’s plate. This information is usually in the small metal plate, where you can find the model number and serial number. For example, an outdoor circular saw shows 15A, which means it has an amperage rating of 15 amps.
Knowing Ohm’s law is important because it helps in keeping you safe when dealing with electricity. To put it in simple terms, you multiply amps with volts to get watts.
Volts (V) x Amps (amps) = Watts (W)
This formula helps understand the different extension cord sizes because it may require you to convert the rating in the tool or appliance to watts. In the US, we use 120 volts in most homes. Some regions across the globe use 240V. It may vary depending on which region you are in, so check before proceeding.
When electricity travels down a long wire, it loses voltage. It happens because electricity encounters resistance as it travels. With this knowledge in mind, only use the extension cord length that you need. It is one of the many reasons why using the correct wire size and length are important. Electrical resistance creates friction, which also creates heat.
To test this out in a simple real-world experiment, rub your hands together. When you do it slowly at first, you may not feel much. As you gradually increase the speed, press down harder. You may feel the heat building up, and it becomes rougher to rub your hands. It is because resistance is building up. The same happens with electricity traveling down an extension cord.
To summarize, do not use a 50 feet long extension cord if you only really need about 20 feet. Purchase an assortment of extension cords with varying lengths. You can use a short one if the outlet is only a few meters away from your project.
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Sizing an extension cord
The first thing you need to do is determining the tool or appliance you will be using with the extension cord. Once you have the information on hand, look into the table in the Electrical Wire Size Chart section. This chart determines the compatible AWG size.
To make things easier for you, below is a list of common electrical tools with their respective amperage ratings.
- Circular saw: 12 amps – 15 amps
- Electric Chainsaw: 7 amps to 12 amps
- Electric Lawn Mower: 6 amps to 12 amps
- Hedge Trigger: 2 amps to 3 amps
- Leaf Blower: 6 amps to 12 amps
- Power Drill: 3 amps to 7 amps
- Reciprocating Saw: 6 amps to 8 amps
- Router: 4 amps to 6 amps
- Table Saw: 14 amps to 20 amps
- Weed Wacker: 2 amps to 4 amps
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Can you connect different gauge extension cords?
Attaching two or more extension cords can sometimes be the only solution if you want to extend the extension cord’s length of coverage. However, this is not a good idea at all. If you practice this at home, immediately unplug these extension cords and buy a longer one to serve your needs.
There is a consideration in stringing two or more extension cords. However, it has to be for a short term, temporary use only. The problem with it is that it creates a risk when using it as a long-term solution. Extending an extension cord with another extension cord could drastically reduce its wattage capabilities. It could lead to a meltdown and fire at worst.
The Consumer Products Safety Commission estimates 3,300 residential units catch fire each year due to extension cords. The common causes include misused cords, damaged cords, overloaded circuits, and short circuits. Connecting two cords is one example of misusing it.
Avoiding the use of extension cords is the ideal solution. However, if this is not possible, consider using a short cord with adequate protection and heavy insulation. There are times it is unavoidable not to use one. In this case, use the shortest length and the correct wire size.
What to look for in an extension cord?
Looking for an extension cord is an overwhelming task, especially if you do not know a lot about it, at least if you aren’t simply buying one of the most common ones, but if you need to provide electricity for more powerful tools. Here are some points to consider when you are shopping for one online or in-store.
Purchase a slightly longer extension cord
Although we do not recommend getting a length that is way longer than what you need, it is good to get the next longest cord. However, if the next available size is way longer, you might want to reassess your measurements.
It is important to know that you should not daisy-chain your extension cords. Plugging extension cords with each other without having thicker wires to compensate for the distance could add electrical resistance between the outlets. High electrical resistance results in voltage drop, which leads to a lower power supply to your equipment. Daisy-chaining them causes unnecessary heat from building up, increasing the risk of a fire. If you are looking for a waste oil heater, we have a curated list for sale.
Thicker cords can carry more electric power
The thickness of a wire determines how much electricity can safely flow through it. A thicker wire can safely carry more electricity over a longer distance, whereas a shorter wire can safely carry electricity over a shorter distance. Thin cables are ideal for low-power equipment such as battery chargers, stereo, and lights. If you plan to use it in power tools such as vacuum cleaners, saws, and drills, you will have to go for a thicker size. The 14-gauge wire is the thinnest we recommend at lengths of 25 feet or shorter.
A cord that can handle at least 15 amps
We recommend a cord that can handle at least 15 amps. Skip a cord that does not have a specification regarding its maximum amperage capacity.
Most flexible cords are for cold weather
Some extension cords are more flexible in cold weather conditions. These are easier to stretch out and bend across your workspace, easy to keep and store, and flexible in tight spaces. When you’re at an electrical store, it is hard to determine if a cord is flexible without actually opening the package. The best way to ensure flexibility is by looking for one compatible with lower temperatures.
Skip multi-outlet ends for heavy-duty tools
It is tempting to get a multi-outlet extension cord because you can plug several tools into it. Getting one is fine if you plan to use it on light-duty equipment. For heavy-duty equipment, we do not recommend a multi-outlet extension cord because it is easier to overload.
For example, an extension can easily handle a circular saw. However, if you plug-in a few other tools into it, you might overload the plug, which could cause a meltdown or start a fire.
How can I tell what gauge my extension cord is?
There are several extension cord gauges you can use. Most cords will have a print of their gauge somewhere in the wire. It may be too small to find, so carefully inspect it. For brand new extension cords that are still in their original packaging, read through the product specifications. The gauge size should be somewhere there.
Doing a quick bend test is another way to have an idea of the gauge. Although this is not a reliable way of determining the size, you get at least an idea. If it is hard to bend or curl, it is probably 16-gauge, 14-gauge, or less. Otherwise, it could be 18-gauge or more.
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A 6-gauge aluminum extension cord has an amperage rating of 50 amps at an ambient temperature of 167°F or 60 amps at an ambient temperature of 194°F. For a 6-gauge copper extension wire, it has an amperage rating of 55 amps at an ambient temperature of 140°F, 65 amps at 167°F, and 75 amps at 194°F. Some thick extension cords are waterproof. It is best practice to check the specifications.
An 8-gauge aluminum extension cord has an amperage rating of about 40 amps at an ambient temperature rating of 167°F or 45 amps at an ambient temperature rating of 194°F. On the other hand, an 8-gauge copper extension wire rates at 40 amps at an ambient temperature of 140°F, 50 amps at 167°F, and 55 amps at 194°F.
Aside from knowing the above information, the safe length for an 8 AWG wire is also important. An 8-gauge wire is thicker than a 10-gauge wire, making it more heavy-duty than the latter. It comes in several lengths, such as 25 ft., 50 ft., and 100 ft. You can use an 8-gauge 50 ft. extension wire with a welding machine. Some long cables are retractable, making it easy for the user to pack it up.
A 10-gauge aluminum wire has an amperage rating of 30 amps at an ambient temperature of 167°F or 35 amps at 194°F. On the other hand, a copper wire of the same AWG has an amperage rating of 30 amps at 140°F, 35 amps at 167°F, and 40 amps at 194°F.
You can use a 10/3 with a ground wire for an apartment size range, a large air conditioner, a built-in single oven, or an electric dry. Only appliances mentioned with an amperage rating of up to 30 amps are compatible. Note that some of these appliances use a NEMA 10-30 three-prong plug, so you may want to pick a multi-outlet extension cord.
A 12-gauge aluminum wire has an amperage rating of 20 amps at 167°F and 25 amps at 194°F. On the other hand, a copper wire of the same AWG has an amperage rating of 25 amps at 140°F, 25 amps at 167°F, and 30 amps at 194°F.
You can use a 12/3 extension cord in a variety of appliances and tools, such as but not limited to air compressors, saws, drills, lawn equipment, vacuums, chargers, heaters, and generators. Some extension cords come in a male to male or double male format. However, never use this as it is dangerous and prone to starting a fire.
In the case of a 14-gauge wire, it usually only uses copper for the conductive part. It has an amperage rating of 20 amps at an ambient temperature rating of 140°F and 167°F, and 25 amps at 194°F.
A 16-gauge wire has a rated amperage rating of 13 amps, which you can use for light-duty extension cords. This type of wire can only support devices that are not power-hungry. Using it with a space heater or any heat-generating appliance, such as clothes iron or toasters, is dangerous.
What gauge wire do I need for 15 amps?
If you have a 15 amps appliance or tool, we recommend you use a 14-gauge copper wire. If it is unavailable, you can pick a larger size wire, such as a 12-gauge or 10-gauge. In choosing the AWG size, you can get a bigger wire without worrying about compatibility issues.