How many devices can you plug into an electrical outlet before it poses a fire risk?

It often happens during the holiday season -- the electrical outlet starts to bear extra load. There are nine sets of lights for the tree, electric candles, a CD player playing festive tunes, and somehow a George Foreman Grill. It almost feels like simply gazing at this tangle of cords will give it the spark it needs to catch fire.

Overloaded outlets are indeed responsible for fires -- approximately 5,300 each year in American homes [source: CPSC]. Nearly 2,000 of these incidents happen during the holiday season [source: ESFI]. With thoughts of flaming sugarplums, Mytour wondered -- just how many things can you plug into an electrical outlet before it becomes a hazard? The answer varies, as several factors play a role in this risk.

To determine how many devices you can plug into an outlet before it becomes a fire risk, we first need to understand how electricity functions. In the average American home, 120 volts of electricity are constantly flowing. Somewhere in your house, you'll find a wall-mounted box containing either circuit breakers or fuses (which are common in older homes).

Circuit breakers and fuses serve as protective mechanisms against electrical overloads. They control the amount of current -- the flow of electrons through a conductor, such as an electrical cord -- that can be drawn from a circuit. This current is measured in amperes, or amps. Most circuit breakers and fuses regulate at 15 or 20 amps.

If too much current is drawn from the circuit, the circuit breaker trips or the fuse blows, effectively cutting off the flow to prevent overload. However, circuit breakers and fuses aren’t foolproof. Another potential risk arises when multiple outlets are connected to a single circuit. If you go to your circuit breakers or fuse box, you might find a single circuit labeled "Dining Room" or "A/C unit and Washer/Dryer". In such cases, an entire room’s outlets could be linked to one circuit, meaning you could overload an entire room's outlets, not just one, leading to a fire hazard.

So how can you figure out what’s too much? It’s actually pretty simple. To calculate how much electricity you're using with your holiday decorations, all you need is a bit of math. The formula is as follows:

p/e=i (wattage divided by volts equals amps).

Suppose you're using 2,000 watts of power with your holiday lights and other decorations. By dividing that number by the volts in your home (usually 120), you get 16.6 amps of current being used. With a 20 amp outlet, you are using about 80 percent of the available current, which is the maximum you should draw per circuit.

On the following page, you will learn about other factors you need to consider in order to keep your holiday season safe and avoid any fiery mishaps.

Electrical Fires

Beyond calculating your electricity consumption, there are other precautions you can take to avoid a Christmas disaster. Factors such as faulty wiring, winter conditions, and poor product choices can all contribute to a holiday fire.

Each year, thousands of counterfeit electrical products are found on the shelves of legitimate stores across the United States. These products are often not designed to handle the additional strain caused by holiday decorations. The Consumer Product Safety Commission (CPSC) works to seize these products whenever possible. The CPSC conducts tests and discovers that many counterfeit items fail even basic safety standards. When a faulty or counterfeit product is identified, the CPSC issues a recall.

Even certified products can contribute to overloads. Electrical devices built to produce heat, such as space heaters and hair dryers, often draw more power than other devices. These devices can overload a circuit, especially one already operating at its full amperage limit. When combined with a malfunctioning circuit breaker, this overload can lead to overheating and, in some cases, cause a fire.

However, fires are more likely to occur in hidden areas. The waste heat from electrical currents can cause wiring concealed within the walls of your home to expand and contract, eventually loosening. When the wiring becomes loose, it can cause electrical arcing, with temperatures reaching 1,500 to 1,800 degrees Fahrenheit.

This is more than enough heat to ignite wood or old insulation under normal conditions. However, winter weather is drier than summer, causing the relative humidity inside walls to drop to desert-like levels. This dryness turns studs – the wooden supports in walls – into highly flammable material that can be easily ignited by electrical arcing.

This is one of the primary concerns with electrical fires: by the time you notice smoke coming from an outlet, the fire has most likely already begun and is spreading unseen within your walls and possibly into the attic. A homeowner who cuts the power to a burning outlet may think they’ve resolved the issue, but an invisible fire could already be growing beyond the outlet.

Electrical fires are notoriously difficult to extinguish. Because they involve electricity, trying to put out the flames with water can lead to electrocution. Chemical powders might cause the fire to smolder, only for it to reignite later. As stated by Georgia Mutual Aid Group state safety officer Phil Choven, if you spot an electrical fire, your first step should be to cut the power (if it’s safe to do so) and evacuate the building. Afterward, dial 911 to report the fire.

Turn to the next page for tips on how to safeguard yourself from holiday-related fires.

Holiday Safety Tips

It’s unfortunate, yet true, that some stores in the U.S. still sell uncertified or unsafe products. Thankfully, there are organizations dedicated to preventing dangerous products from making their way into your home.

Underwriters Laboratories (UL) and Factory Mutual are two independent organizations that certify products for safety. They test electrical items, among others, to see if they ignite when plugged in. If the product passes this test, these organizations will certify it and place a label on it for shoppers to easily identify. Besides looking for such labels, the Electrical Fire Safety Foundation International advises avoiding products like extension cords and circuit breakers from discount retailers. It's also wise to opt for trusted name brands when purchasing such items. Be vigilant in checking labels—any spelling mistakes or poor grammar can be a warning sign that the product is from an unreliable manufacturer.

At home, be cautious about overloading your power supply. It's easy to calculate the power you're drawing from your outlets, and doing so can help prevent a fire. Christmas lights are generally low wattage, with 50 bulbs consuming around 25 watts. If your circuit can handle up to 2,000 watts, you should be safe, as the brightness of so many bulbs would likely irritate your eyes before overloading the outlet. However, devices like space heaters require far more power than holiday lights. Unplugging one device before plugging in another can reduce the risk of an electrical fire. Don't forget to unplug all decorations before heading to bed.

It's also a smart practice to inspect the wiring of your holiday devices. If the wiring is frayed or worn, it's time to replace the device. The rubber insulation is designed to prevent excess heat and avoid current arcing, and without it, the risk of a fire significantly increases. Be on the lookout for old plugs that don't fit snugly into outlets, as these can spark, especially if the outlet is near a dry, sap-filled pine tree.

In the end, there's no exact number of plugs that will cause an outlet to catch fire—it depends on the situation. It’s best not to test this yourself. Instead, this holiday season, familiarize yourself with the electrical specifications of both your home and the devices you plug in. Be mindful of how many devices are on a single circuit and consider leaving extra decorations in the attic this year. Otherwise, those chestnuts might end up roasting on an unintended open fire, whether you planned it or not.

For more details on electricity and fire safety, check out the next page.