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What Size Extension Cord Do I Need for a 1500 Watt Heater?

Written by Edwin Jones / Fact checked by Andrew Wright

what size extension cord do i need for a 1500 watt heater

Proper sizing of the extension cord and device power rating is crucial for the safety of our home. If you’re wondering, “what size extension cord do I need for a 1500-watt heater,” in most cases, a 14-gauge extension cord will suffice.

However, other than the wire size, you also need to consider some factors that we will discuss below.

What Wire Size is Recommended for 1500w Heater Extension Cord?


It is critical for the device’s safety and efficiency to use just the right extension cord. This way, the current flows smoothly along the wire up to your device, causing no electrical problems while ensuring that the unit has enough power.

As previously stated, a minimum 14-gauge extension cord is suggested for a 1500 watt space heater. You are more likely to cause an electrical hazard if you use a cable smaller than this size.

This is due to the fact that a small extension cord might not be able to manage the loads required by the heater. In this case, you may find that the heater melted extension cord and started a fire.

Additionally, there are various types of extension cords on the market today. Therefore, it is preferable if you have an idea of which type is best for your heater. Let us discuss this further below.

Types and Sizes of Extension Cords for a Space Heater


A space heater is a high-powered appliance that consumes a lot of electricity. As a result, you may only be able to use a heavy duty extension cord with space heater. This way, you can guarantee the cord’s safety.

Heavy-duty extension cables are often 14 gauge, 12 gauge, or 10 gauge and can handle loads up to 15 amps.

In addition, you may come across an extension cable with a W rating on its label in the market. W stands for weather- or water-resistant. In general, this type has strong enough insulation to be used in an outdoor application.

If you have a space heater that requires a 1500 watt extension cord, you should consider getting one of these sizes and types.

Extension Cord Amperage Chart


To size cable, you must also consider the length needed in your application. This is because the current must travel a considerable distance, resulting in a voltage drop. Also, remember that the maximum permissible voltage drop for longer lines is under 5%.

This indicates that the longer the wire, the less current it can carry. Therefore, if you need a cord for a long application, you might require a bigger gauge.

To help you understand this voltage drop condition, below is an extension cord wattage chart showing how much current a cord can carry based on its length.

Extension cord size Maximum power rating at 110v (watts) Amperage per length of the extension cord (amps)
25 ft. 50 ft. 100 ft.
16 AWG 1,430 watts 13 amps 13 amps 10 amps
14 AWG 1,650 watts 15 amps 15 amps 13 amps
12 AWG 1,980 watts 18 amps 18 amps 15 amps
10 AWG 2,200 watts 20 amps 20 amps 20 amps

Frequently Asked Questions

Can I Use a Heavy-duty Extension Cord with a 1500 Watt Heater?

Using an extension cord with a space heater is not really advisable. However, only the heavy-duty type should be considered if you have to use an extension cord. This type is sturdy enough to support the heater’s loads.

Moreover, it would also be beneficial to utilize an oil heater extension cord that is as short as possible. This way, the electrical current does not have to travel a great distance, preventing voltage drop.

How Many Amps Does a 1500 Watt Heater Require?

On high settings, a 1500 watt space heater draws an average of 12.5 amps. As a result, it may require a minimum of 15 amps to run safely. Just bear in mind that if you put it on a 15 amp circuit, you might not want to hook anything else into it as it could overload the circuit and trip the breaker.


Overall, a 14-gauge heavy-duty extension cord with a length of 25 feet is recommended for a 1500 watt space heater. With it, you can provide a good power source for the device while also preventing any electrical problems that could cause fire or harm to the unit.

This article answers the question, “What size extension cord do I need for a 1500 watt heater.” However, it is best to follow the manufacturer’s recommendation for safety guidelines when using the heater.

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