What Size Extension Cord for Generator? [Explained]

When using a generator, an appropriate extension cord must always be used. Most likely, the regular indoor extension cord you already have won’t be sufficient. You will want a special cable that can resist the power without overheating, depending on the load of the electrical gadgets and the current of the outlet you select to utilize in your generator. A particular generator extension cord is necessary to avoid potential fire and electrocution risks. In this article, we’ll discuss what size extension cord for generator is best.

Table of Contents

What Factors Determine the Size of the Extension Cord for a Generator?

1. Length

Extension cables market in increments of 25 feet. However, they can be anything between 25 and 250 feet.

The electrical resistance a cord produces increases with its length.
So, a shorter extension cord will carry power more effectively and require less generator work.

2. Gauge and Amperage

The American wire gauge (AWG) rating on extension cords defines how much amperage (a unit of electricity) they can support.
A cord will be thicker and capable of carrying more amps if its AWG is lower. Although you should equal your generator’s amperage, you can go one grade lower than required to increase the cord’s ability to run any electrical equipment with generator electricity.

3. Shape of the cord

Extension cords with three grounded prongs are generally typical, but they’re not the only design you can buy. Others bend and lock into place or have four prongs. Ensure the cord you purchase is the right length, has the right AWG rating, and is correctly plugged in.

What Factors Determine the Size of the Extension Cord for a Generator?

What Size Extension Cord for Generator?

If you know the ampacity, use the wire ampacity chart to determine the size of wire your generator requires. Calculating the generator amperage consumption is the first step in determining the ampacity.

If you are aware that you have a 50 amp/ 50A, 100 amp/100A, etc. generator, this has already been done. If you merely know the generator’s wattage, you can compute the amps.

Below is a detailed explanation of how to calculate the generator wire size step-by-step:

  1. To determine the amp draw, divide the generator’s power by its Voltage.                Wattage/Voltage = Amp Draw. (A=W/V)
  2. Multiply the amperage draw by 1.25 to accommodate for the 80% NEC regulation. The National Electricity Code (NEC) states that any circuit breaker’s maximum load is 80% of its rated ampacity. It serves as a safeguard to keep you from overloading the circuits (overloading of current may cause a fire)
  3. After determining the required minimum ampacity, refer to the Wire Ampacity Grid and choose a wire with that ampacity or more.

What Types of Extension Cords are Suitable for Use with a Generator?

1. Outdoor/Portable generator extension cord

Placing a portable generator outside and connecting the extension cord to the chosen appliance through an opened window or door is the most typical method of use. You are protected from any potentially dangerous gases by doing this, as generators release carbon monoxide. If you camp, this type of extension is useful. Your wire cord can use for equipment outside.

2. Indoor extension cord for a generator

Carbon monoxide gas, which might knock you out, bring you a headache, or even kill you, is emitted by generator engines. Though it’s simple to avoid, keep your generator at least 10 feet from your home, and avoid running it on your porch or garage. Heavy-Duty Extension Cords Are Required for Connecting to Appliances. Use a “manual transfer switch” as a fix.

3. Light-duty extension cord gauges

The most widely used extension cord sizes for light-duty are 14 AWG, 16 AWG, and 18 AWG. The gauge selection depends on the length of the cable. The gauge number increases as the length decreases.

4. Heavy-Duty Extension Cords

Heaters are heavy-duty appliances that require heavy-duty extension cords. These cables have an ampacity of up to 15 Amps. They come in sizes ranging from 14 AWG to 10 AWG.

VIDEO CREDITS: SFM Preparedness YouTube Channel

What is the Maximum Length of Extension Cord that Should be Used with a Generator?

Extension cords (eX; Generac Brand) use specifically for generators with 30 Amp, 10 or 30 feet long, and rated for up to 7500 watts of power.

Some people have chosen to upgrade to a 50Amp wire because most outlets only provide a maximum of 30Amps, although doing so can be expensive. With most 120V/240V portable generators, the cord length mentioned above is a secure option. As long as you don’t connect more than 30 Amps in total, you should be fine because this type is capable of 300V.

You can choose the gauge or length of wire to use based on the National Electric Code (NEC) recommendations for amperage. If you need to go a long distance, you must increase your gauge because the resistance of wires will cause your voltage to drop over time.


How Long Should the Extension Cord with a Generator?

Make sure your extension cord is long enough to place the generator minimum of 20 feet from the house while you’re using it to prevent carbon monoxide from entering your home. The extension cord’s length cannot exceed 50 feet. This is because a lengthy extension cord won’t be able to support a heavy load and will become excessively hot.

Does the Length of an Extension Cord Affect the Power?

Yes. A cord can only operate an appliance of a specified wattage at a given distance dependent on its gauge. The cord’s current carrying capability decreases as it gets longer due to the rise of resistance with the length. For instance, a 1625-watt (W) appliance can be powered by a 16 AWG extension cord that is less than 50 feet long.

Can you Use Regular Extension Cords with Generator?

Can’t say for sure. This depends on the maximum operating wattage of the extension cord, the power requirements of the appliances or power tools you intend to use, and the cord length. Low-wattage electrical appliances like TVs, phone chargers, and lamps can typically only be used with a short conventional extension cord.

The majority of ordinary extension cords are too long or too thin in the surface area to use for a generator that must operate outside. If you wish to power up your RV, which requires a 50-amp electrical source, this becomes much more critical.

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