Many of us will spend more time indoors as cold weather moves in. As we start to find ways to stay cozy with space heaters, heated blankets and more layers, we’ll strain our home’s electrical system more. It’s important to be aware of what you're plugging into outlets and where.

In my years of testing portable power stations and other energy monitoring devices, I've learned that anything that heats or cools requires serious power. This means that when you plug in your heaters and blankets to ward off the chill of winter, you may want to think twice about plugging them into a smart plug.

Home electrical system basics

Smart plugs are great for many things, but even the best smart plug has limitations. In the US, our homes primarily operate on 120 volts, with some appliances requiring 240 volts. However, the breaker box is the other part of the puzzle regarding our home’s electrical system.

Typically, this is hidden in a closet or a utility room in the basement and will have a gray door. Inside are circuits that help break up your home's electrical usage into smaller pieces so as not to overload your system. Those circuits have breakers with amperage ratings. If that limit is exceeded, the breaker will trip and shut off power to those devices plugged into it to prevent potential fires.

Using an electrical monitoring device can help check your home's system for potential issues as an added layer of prevention. Products like the Ting Sensor, which is offered in partnership with some insurance companies, check for electrical hazards over 3,000 times per second.

Certified electrician Derek Rhoades of Tradecraft Electric offered insight into our home’s circuits, “Typical receptacles, often called 'outlets,' are most commonly rated for 15 and 20 amps. Amps, or 'amperage,' generates heat as it flows through a circuit. The receptacles need to be able to handle the amount of amps that flow through them.”

The outlets that Rhoades is referring to are the ones hardwired into your home’s walls. Smart plugs generally mirror the same amperage ratings. Most smart plugs are rated for 15 amps, but some are only 10 amps.

Aside from amp limitations, smart plugs also have a relatively low operating temperature. As Rhoades points out, “Heating loads, such as space heaters, can be the most damaging to devices and circuits. They not only generate heat as its intended use but also as a byproduct of the large amount of amps that flow through the circuits they operate on.”

Looking at the chart above, you can see that the ratings for smart plugs, hardwired outlets and outdoor plugs are all very similar. However, there are a couple of outliers in the Aeotech Heavy Duty Smart Switch and the Leviton GFCI Outlet. These two offer higher amperage ratings and, in the case of the Aeotech product, can also operate at 220 volts. But it isn’t a plug; rather, it requires appliances to be hardwired directly into the device.

Smart plug awareness

Just as you need to know what you’re plugging into extension cords and power strips, the same goes for your smart plugs. Most space heaters, including those on our best space heater list, have a max wattage rating of 1,500. It’s important to be aware how much electricity an appliance will draw and the circuit, breaker, you are connecting it to. 

For example, your 1,000-watt microwave is plugged into a circuit with a 20-amp breaker and you then plug in your space heater, there is a risk of overloading that circuit if both appliances are running at the same time. 

Looking back at the chart from earlier, all those 15-amp smart plugs match up well with the 15- and even 20-amp breakers your home uses. However, smart plugs aren’t as durable as the hardwired outlets in your home’s walls. “A 15-amp device is capable of handling 1,800 watts, but a device with that much wattage should only be run at that level for short periods, three hours at the most,” Rhoades says.

“If the load you plan on plugging into a 15-amp device exceeds 1,500 and will run for a sustained period, it should stick to a max of around 80% of that full load, which comes to 1,440 watts.”

Space heaters have benefits, but certain steps should be taken to use them safely. Most smart plugs can handle a space heater. When choosing your heater and where you’re plugging it into, ensure the power needs of the heater, generally 1,500 watts on high, and the outlet or plug is rated high enough to handle the heater’s electrical draw safely.

When using a smart plug, try to get one with a rating higher than 15 amps, but those are relatively uncommon. Another way to reduce the risk of problems is to run the heater on a lower setting, requiring less power. However, using two space heaters on the same outlet, even on lower power settings, will overload the circuit, as you’d be doubling the power needs.