Can You Safely Run Your Air Conditioner on an Extension Cord?

If you’ve recently purchased an air conditioner to combat the scorching summers but find its cord doesn’t quite reach the nearest outlet, you might wonder if running it on an extension cord is a viable option. You should know that while it’s possible as a temporary solution, there are essential factors to consider and safety measures to take.

How to Choose a Suitable Extension Cord for Your Air Conditioner

To start, not just any extension cord will do. AC units require heavy-duty extension cords to handle the significant power they consume. Here’s what you need to know to ensure a safe and effective setup:

Current Capacity

Check your unit’s power efficiency, typically found in the owner’s manual. This percentage represents the power input that converts to output, with the remainder lost through various factors. Your extension cord should match this efficiency to minimize power loss.


If your manual doesn’t provide power efficiency data, determine your unit’s power needs by finding its wattage and expressed voltage. Divide the watts by the voltage to get the required amperage. The extension cord you use should match this amperage, and also consider the amp ratings of any circuits involved to prevent overloading.

Wire Gauge

The wire gauge indicates how much electricity the cord can safely transfer. As a rule, choose a cord with a gauge that can handle at least double the required amps of your AC unit. For most units, a 12-gauge wire is sufficient, but larger units might need a higher gauge.


Opt for the shortest extension cord possible to minimize resistance and prevent hazards like electrocution or fires. If a longer cord is necessary, increase the gauge to compensate for resistance and maintain safety.


Select an extension cord with three prongs instead of two. Three-prong cords provide grounding, which safely disperses excess electricity, preventing potential issues like power surges, AC unit damage, or electrical fires.

Related: 10/2 or 10/3 Wire for Air Conditioner

Is It Safe to Plug AC into an Extension Cord?

Although it’s easy to plug appliances into extension cords, we do not recommend plugging an air conditioner into an extension cord. This is because it puts the electrical system at risk of developing electrical fires that may damage the building. Electrical fires occur when the electric current of the AC is higher than what the extension cord can handle.

Instead, for safer use, an air conditioner should be plugged into a grounded socket that can handle high voltage. This is why ACs come with a short thick outlet cord. The short thick power cords are designed to handle high amounts of electricity compared to thin outlet cords that would be overwhelmed by the high voltage.

What Gauge Extension Cord Do You Need for AC?

In case you have no option and need to use an extension cord for your air conditioner, we recommend that you opt for a heavy-duty cable that can handle the voltage of the air conditioner. Heavy-duty extension cords tend to be shorter with high amps such as the 14-gauge wire or the 12-gauge wire.

The lower the electric gauge, the more current the extension cord can handle. We recommend 12-gauge wire extension cords if you need to buy an extension cord for your air conditioner unit.

How to Safely Use an Extension Cord for an Air Conditioner

While running your air conditioner on an extension cord is possible, it’s crucial to consider it as a last resort. Before resorting to this option, consult HVAC technicians, who can offer better solutions, such as replacing the original power cord, installing new outlets, or using portable AC units.

If using an extension cord is unavoidable, familiarize yourself with the dangers associated with its use. Check for overheating and voltage drops, and ensure the cord remains visible to prevent hazards. Always plug the extension cord directly into a wall outlet, avoid hiding it under furniture or rugs, and don’t use additional cords or power strips to increase length.

With a lifelong fascination with HVAC mechanics and a mechanical engineering degree from Berkeley, Thomas Johnson boasts years of industry expertise. He founded to fill the void of understandable and useful online information about complex HVAC systems. As the chief editor, Thomas strives to provide accurate and engaging content to help readers make informed HVAC decisions.

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