It takes power to keep a job site humming. But when it comes to electricity, that power isn’t always where you need it. That’s where extension cords come to the rescue. The right cord will put you in business. The wrong one could shut you down.

Size Matters

Think of power cords as being hoses for electricity. You don’t want to put out a forest fire with a garden hose, but if you use one of those big boys the firefighters use on a flowerbed, the petunias will end up in a neighbor’s yard and you might blow away enough soil to reach bedrock. As with so many other things, size matters.

Simple Amp and Power Conversion Formulas

You don’t have to be an electrician to pick the right extension cord, but you do need to do some basic math. Power is measured either in amps (comparable to water pressure in a hose), or watts (the amount of water coming out). Cords are usually marked with the amps they will safely carry, but your tool power may be listed in watts—or even horsepower. To get from one to another, here are some basic formulas:

Watts = Volts x Amps Amps = Watts / Volts 1 horsepower = 750 Watts

So a 5hp saw like the CC3500 Electric Self Propelled Concrete Saw has 3,750 watts of power (5 x 750), and if it’s running on 240 volts it will pull just under 16 amps (3750/240). A 2800-watt 16" hand-held TP 400 Cardi Electric Saw will pull about 20 amps at 120 volts.

National Electrical Code (NEC) Requirements

The National Electrical Code (NEC) has several rules for using extension cords including where and how they should be used. It also sets limits on the amount of current that cords are permitted to carry to prevent overheating the cord. The limits for common wire gauges are listed below:

Copper wire size(AWG) Single-phase 2-wire and 3-wire cords Three-phase cords (motors, etc.)
16 13 amps 10 amps
14 18 amps 15 amps
12 25 amps 20 amps
10 30 amps 25 amps

Just like a hose, a cord will also lose output based on friction, so the cord’s length becomes a factor, too. Prefab cords will have a load capacity stamped on them that takes the cord length into account.


Horsepower     Phase     Voltage    Amps  
5 3 230 12
5 3 460 6
7.5 3 230 17
10 3 230 24
10 3 460 12
15 3 230 36
15 3 460 18
20 3 230 52
20 3 460 26
25 3 230 58
25 3 460 29
30 3 460 37

Professional Expertise

At Ace Cutting Equipment, our people know how to match our selection of electric concrete saws with the extension cord that’s right for your power needs. We have over 100 years’ combined work experience at your service to help in choosing the right tools for your job. Give us a call at (888) 283-2597 or email and we will gladly help with any questions you may have.

And be sure to visit our newly designed web site,, to see the many ways our American-owned family business is always on the cutting edge when it comes to equipment and supplies for the concrete and masonry cutting industry.

Have Questions about this Product? Call us at (888) 283-2597 or email us and we will help with any questions you may have.