If you're planning on using an extension cord for your freezer, it's important to know at the outset that no safety agency or electrical association recommends using it permanently. The National Electrical Code and the National Fire Protection Association expressly prohibit it. Mike Holt advises that you'll find the prohibition elucidated in Article 400 of the NEC, and it's also in Section 11.1.5 of the NFPA Fire Code.
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Extension Cord Dangers
Electrical inspectors aren't the FBI, and they won't come to your door looking for electrical violations, so it's up to you to use your extension cords safely. Extension cords are intended for temporary use, but it's easy for temporary to turn into permanent. Especially when it comes to a freezer, which may be situated in a part of the house that people don't visit very often. Knowing this, if your fridge cable is not long enough, it's even more important to follow all the guidelines for safe extension cord use to avoid causing one of the 3,300 home fires caused by extension cords that occur annually in the United States, according to the Electrical Safety Foundation International.
Running Extension Cords Through Rooms
Perhaps you bought a new freezer or maybe you're moving one from one room to another, and you discover that there's no receptacle within range of the power cord. The safe and correct responses to this situation are to either adjust the position of the freezer to be closer to the receptacle or to install a new receptacle.
When neither is possible, an extension cord offers an easy alternative as long as there is a receptacle in the same room. The electrical and fire codes prohibit passing the cord through a wall to another room or running it through the doorway or a window. Two safety considerations are behind these prohibitions.
The first consideration is that a temporary cable could get damaged, perhaps by rodents or — if you leave it long enough — age deterioration, exposing the wires and creating a fire hazard. Because it's behind the wall, you'd never know until it's too late. The second consideration is that the cord creates a tripping hazard and is exposed to other types of damage when you run it through a door or window.
Using the Right Gauge
A typical refrigerator or freezer draws 15 amps of current at 120 volts, and that amount of current calls for a 14-gauge cable at a minimum. However, 12-gauge cable is safer because refrigerator and freezer compressors can draw more than the rated current every time they cycle on. The extra current overheats smaller 16- and 18-gauge extension cords, which are intended for lamps and small appliances, and you should never use one for a refrigerator or freezer.
Use the Shortest Cord Possible
You'll want to use a short cord for two reasons. The first is that a long cord just gets in the way. You may have to coil it up and stow it behind the freezer. This prevents you from pushing the freezer against the wall to eliminate a perfect nesting space for rats and mice. Moreover, the more excess cord there is, the more chances there are for the cord to get damaged.
The second reason is that a long cord affects the performance of the freezer. The voltage drop across a long cord can be significant. If the freezer compressor operates at a lower voltage than it should, the cooling will be less efficient, and the compressor could fail to cycle on when needed.
Use a Single Cord
Perhaps you have several extension cords on hand, but you don't have one long enough to reach the receptacle. The solution is to use two cords, right? Nope, that's another prohibition you'll find in both the electrical code and the fire code. You need to buy a new cord that will reach.
The reason is that extension cord connections have a nasty habit of working themselves loose, exposing the pins and creating a hazard. Suppose someone spills a bucket of water in the vicinity of the connection, which could easily happen in a busy kitchen. If the water collects under the connection, you've got a pool of electrically charged water that could seriously injure a child or pet who gets too close to it.
Grounded Extension Cord for Freezer
The power cord on a freezer or refrigerator has a ground pin, so you need a UL® listed 3-wire grounding appliance extension cord, and you must plug the cord into a grounded three-pin receptacle. It isn't safe or acceptable to remove the ground pin from your extension cord so you can plug it into a two-pin receptacle. If you use a three-pin to two-pin adapter, you must wire the ground tab on the adapter to ground using the same gauge wire as in the cable.
If you put the freezer in the garage or someplace outdoors that requires you to plug it into an exterior receptacle, use an extension cord rated for outdoor use. Whether you use an interior cable for an indoor receptacle or an outdoor cable for an exterior one, it's important to check the cable for cracking or exposed wires. Never use a damaged extension cord.
Don't Secure the Cord
If the receptacle is on the opposite wall from the freezer, it seems to make sense to run it across the floor and hide it under a rug. That's just as dangerous as running it behind a wall and is also prohibited by the electrical and fire codes. If the cord gets damaged, the exposed wires could ignite the carpet.
"OK," you say, "I'll staple it to the baseboards." That's also prohibited. Assuming the staples don't puncture the sheathing, staples corrode and the corrosion can eat through the sheathing, exposing the wires and creating electrically charged staples that can give you a shock. If this prohibition seems onerous, remember that extension cords are intended only for temporary use and that the proper way to power your freezer is to install a new receptacle.
Create a Dedicated Circuit
The current electrical code requires every refrigerator and freezer to be plugged into a dedicated circuit with its own 20-amp circuit breaker to prevent overloading the breaker and causing it to trip when the appliance cycles on. Chances are that if you're using an extension cord, you'll be plugging the refrigerator or freezer into an existing circuit. To achieve the safety standards required by the NEC, you should eliminate — or at the very least reduce — other loads on the circuit.
An effective and easy way to do this is to install cover plates on other receptacles on the circuit so you can't use them. This workaround to the code-prescribed method of powering the freezer, which is to run a new 20-amp dedicated circuit, may be impractical if your house doesn't have enough outlets. If you don't do it, though, the breaker on the circuit you use may trip frequently. It isn't safe or legal to address this by simply replacing the breaker with one that has a larger current rating.