The best extension cord for your generator is one that is specified to handle the power that’s being delivered between the generator itself and the device or devices plugged in.
I suspect that some people don’t know that it does make a difference having the right or best extension cord (or cords) when powering appliances and other devices.
What difference does it make?
If the extension cord is ‘too small’, not only will it heat up but it will potentially restrict the power necessary to safely operate certain devices plugged in.
What do I mean by ‘too small’?
I mean the internal wires themselves. Wire is rated in “gauge”. Thin wire can only handle lesser power while thick wire can handle more power.
Don’t let the thickness of the cord fool you. While generally speaking the thicker the appearance of the extension cord, the thicker the wires inside ‘probably’ are. However not necessarily!
Check the gauge!
There are LOTS of extension cords that are #16 and #14 gauge. What you want is #12 gauge wire inside. Check the package. Somewhere on the label it will indicate this.
For wire, the smaller the gauge number (#) rating, the more power it can handle. So #12 can handle more power than #14 or #16, etc..
Note: In the United States the domestic voltage is 120 V, and the National Electrical Code (NEC) prohibits the use of extension cords in a 20 A circuit unless they are of 16 AWG or larger diameter (for example, 14 AWG or 12 AWG).
Why is #12 gauge Extension Cord Better?
There are a number of factors that contribute to the ratings for extension cords and they vary somewhat. However generally speaking here are some specifications that I sourced from “Southwire”, a well known wire company.
16/3 extension cord
13 amps at 50 feet
1560 watts @120 volts
14/3 extension cord
15 amps maximum at 50 feet
1800 watts @120 volts
12/3 extension cord
15 amps at 100 feet
1800 watts @120 volts
Note: The “/3” simply means there are three wires within the insulation of the extension cord. One is for ground (green), one for “hot” (black), and the other for neutral (white).
Generally speaking most wire specifications reference the following:
#16 (13 amps, or 1560 watts @120 volts)
#14 (15 amps, or 1800 watts @120 volts)
#12 (20 amps, or 2400 watts @120 volts)
The bottom line is to check the packaging label for specs because there are some slight variations between manufacturers and designs.
How does length affect extension cord ratings?
It is fairly significant. Particularly when operating an emergency generator outside you will likely need a fairly long extension cord to get the power inside. So it is important to have the best extension cord for distance and power handling ability.
While the Southwire ratings for a 14/3 and 12/3 extension cord are both 15 amps, the 12/3 cord can be as long as 100 feet at that rating.
Can I use 2 extension cords for my generator?
If your generator puts out more power than the rating of one extension cord, and if your generator has multiple outlets, you can use more than one extension cord. Just don’t overload your cords.
For example, one of my generators is rated for 3500 watts. It has several outlets. I will use two 12/3 extension cords to deliver power inside to my various appliances if need be.
Use Outdoor rated extension cords
Some are rated for indoor only use while others are designed for outdoor use. For use with a generator, you definitely want outdoor rated. The differences are in the insulation material, strength, and the ends themselves (plug & receptacle design).
Warning signs of overloaded extension cords?
-extension cord becomes warm, very warm, or hot
-the generator circuit breaker keeps tripping
-your appliance is making a funny noise
So what is the best extension cord?
A good general purpose choice is a 12/3 (#12 gauge) outdoor rated extension cord.
Yes a 10/3 will perform better than a 12/3, however most all typical building circuits are 15 amps (some are 20) and at a certain point you reach overkill. And if you have a generator that’s putting out LOTS of power you probably already have it “wired in” to your home via a transfer switch or switches along with professional wiring.