Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.
Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.
Summary
An undersized extension cord can overheat and catch fire, even though the appliance works normally. You will read three values printed on the products — the appliance current, the cord gauge, and the cord length — and match them. This procedure shows you where to find them and what to check.
Necessary equipment
| Item | Note |
|---|---|
| Paper and pen (optional) | To record the appliance current and cord length before reading the cord label. |
| Extension cord material | The cord you intend to use. You will read the label. |
| Appliance or power tool material | The device you want to power. You will find its current draw on its label or manual. |
Specifications
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
Find the three values
Estimated 3 min
- LOCATE THE APPLIANCE CURRENT ON ITS LABEL OR MANUAL. The value is in amps (A). If the label shows only watts (W), divide by 120 and round up.1mReport a problem with step 1, Find the three values
- MEASURE THE CORD LENGTH NEEDED. Measure from outlet to appliance. Round up to 25, 50, 100, or 150 feet.1mReport a problem with step 2, Find the three values
- READ THE AMPERAGE RATING ON THE CORD LABEL. The rating is in amps (A). Write it down next to the appliance current.<1mReport a problem with step 3, Find the three values
- READ THE WIRE GAUGE ON THE CORD LABEL. Look for AWG: 16, 14, 12, 10 or lower. The number is thicker when it is lower.<1mReport a problem with step 4, Find the three values
Match the values
Estimated 2 min
AN UNDERSIZED CORD OVERHEATS AND CAN CATCH FIRE.
The appliance will work normally even though the cord is unsafe. Never assume it is safe because it powers the device.
- COMPARE THE CORD RATING TO THE APPLIANCE CURRENT. The cord rating must be equal to or higher. If not, do not use this cord.<1mReport a problem with step 1, Match the values
- CONSULT THE CORD MAKER'S DOCUMENTATION OR CPSC GUIDANCE. Match the cord gauge to both its length and your appliance current. Get a thicker cord if the label or guidance shows you need one.1mReport a problem with step 2, Match the values
- INSPECT THE CORD FOR DAMAGE. Look for cracks, breaks, exposed wires, bent pins, or crush marks. Discard it if damaged.1mReport a problem with step 3, Match the values
Terminology
This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.
- American Wire Gauge
- Also called: no common alternatives
- amperage
- Also called: no common alternatives
- extension cord
- Also called: no common alternatives
- wire gauge thickness
- Also called: no common alternatives
When to use a professional
Call a qualified electrician if your appliance uses more than 20 amps. Call a qualified electrician if you see scorch on the cord or if the cord is too warm.
Common questions
Why does an undersized extension cord cause a fire if the appliance works normally?
An undersized cord has thin wires that resist electrical current flow. The resistance generates heat inside the cord jacket, even though the appliance operates normally. Over time, the cord's insulation fails and the bare conductors can contact flammable materials nearby. The appliance works because it only draws the current it needs; it does not know or care whether the cord is too thin. This is why you cannot rely on the appliance working as a sign that the cord is safe.
How do I check the wire gauge if I am not sure?
The extension cord's label shows the gauge as AWG. Look near the plug or along the cord. Common gauges are 16, 14, 12, or 10 AWG. If you cannot find it, check the box the cord came in, or contact the cord maker. Never use a cord if you cannot verify its gauge.
Can I use a 16 AWG cord for a 15-amp appliance?
Consult the extension cord maker's label and the appliance manual. A 16 AWG cord is rated for a maximum of 13 amps according to published standards. If your appliance draws 15 amps, you may need a thicker cord depending on the cord length. Check both the cord label and the appliance manual to be sure.
Does the age of an extension cord matter?
Yes. Older cords may have brittle insulation that cracks or peels, exposing the conductors. Before using any cord, inspect it for visible damage: cracking, crushing, burn marks, exposed wires, or loose plugs. If you find damage, discard the cord or take it to an electrician for repair. Do not tape over damage; the problem is inside the insulation as well as outside.
Can I use a two-prong (ungrounded) extension cord for a three-prong appliance?
No. A three-prong plug has a ground pin for safety. If you use a two-prong cord with an adapter, the ground connection is lost and the appliance loses its ground protection. Always use a cord with the same number of prongs as the appliance plug, or consult an electrician about a safe alternative.
Related procedures
Sources
Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.
Revision history
Current version 1 · updated 2026-08-03 · next review due 2027-08-03
- v1 · 2026-08-03First publication.
Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.
Comments and corrections
Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.
Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.