What Should You Not Plug Into a Smart Plug? Safety Guide

1. Never Use Smart Plugs With Heating Appliances

Heating devices are the most dangerous things you can plug into a smart plug. These appliances use heating elements that draw huge amounts of electricity for long periods of time. The constant high power demand creates excessive heat that can melt the plastic housing of your smart plug, damage the internal circuits, and potentially start an electrical fire in your home.

• Space Heaters: Most portable heaters use between 1,200 to 1,500 watts of power. This puts them right at the limit of what a standard smart plug can handle. The prolonged heat generation stresses the plug's components and creates a serious fire hazard. Always plug space heaters directly into wall outlets.
• Hair Dryers and Curling Irons: These bathroom devices pull 1,000 to 1,875 watts when in use. The combination of high wattage and moisture in bathrooms makes them especially risky. A smart plug could overheat and fail while you're using these styling tools.
• Electric Blankets and Heating Pads: While these seem safer because they feel warm rather than hot, they still draw power continuously for hours. The sustained electrical load can cause your smart plug to overheat during the night when you're sleeping and can't notice warning signs.
• Toaster Ovens: These kitchen appliances typically use 1,200 to 1,800 watts. Their heating coils create intense heat, and the appliance already gets very hot during normal use. Adding a smart plug to this setup doubles your fire risk because you're creating another heat source in the circuit.

2. Understanding Wattage and Amperage Limits

Before we discuss more devices you shouldn't use, you need to understand how electricity works. This knowledge helps you make smart decisions about what should you not plug into a smart plug. Every electrical device has a power rating measured in watts (W) or amps (A). Your smart plug also has a maximum rating, usually 15 amps or 1,800 watts at 120 volts.

The Math Behind Safe Usage

To find out if a device is safe, you need to know its power consumption. If your device lists amps, multiply that number by 120 volts to get watts. For example, a 12-amp appliance uses 1,440 watts (12 x 120 = 1,440). This would work with most smart plugs, but it's close to the limit.

The 80% Safety Rule

Electrical experts recommend never using more than 80% of any outlet's capacity. For a 15-amp smart plug, that means staying under 12 amps or 1,440 watts. This safety buffer prevents overheating and gives you protection against power surges that can happen in your home's electrical system.

Some devices have two power ratings. The peak load is the power needed when the device first starts up. The continuous load is what it uses during normal operation. Smart plugs can handle short peaks, but sustained high loads cause problems. Always look at the continuous power rating.

Different brands of smart plugs have different maximum ratings. Some budget models only handle 10 amps, while others can manage 15 amps. Always read your smart plug's manual and check the label on the device itself. Never assume your plug can handle the maximum standard household load.

3. Medical and Life-Support Equipment

One of the most critical rules about smart plugs is to never use them with medical devices. These appliances and equipment serve life-saving purposes, and they need reliable, uninterrupted power at all times. Smart plugs can fail, lose WiFi connection, or accidentally turn off through a misplaced voice command or app error.

• CPAP and BiPAP Machines: People with sleep apnea depend on these breathing devices every night. If a smart plug loses connection or accidentally shuts off, it could stop the machine while you're sleeping. This creates a dangerous medical emergency. Always plug CPAP machines directly into a wall outlet with battery backup if possible.
• Oxygen Concentrators: These medical devices provide life-sustaining oxygen to patients with respiratory problems. They need constant, reliable power with zero interruptions. A smart plug malfunction could cut off someone's oxygen supply, creating an immediate life-threatening situation.
• Medical Refrigerators: Some medications and medical supplies like insulin need refrigeration at specific temperatures. If a smart plug turns off your medical fridge, those medicines could spoil and become dangerous or useless. The cost of lost medication far exceeds any convenience a smart plug might offer.
• Home Dialysis Equipment: Kidney dialysis machines are complex medical devices that require stable electrical power. Any interruption during treatment can be dangerous for the patient. Medical equipment should always use dedicated circuits without any smart home devices between them and your home's electrical panel.

4. High-Power Kitchen Appliances to Avoid

Your kitchen contains some of the highest power-drawing appliances in your home. Many of these devices use heating elements or powerful motors that exceed safe limits for smart plugs. Understanding which kitchen appliances to avoid helps prevent electrical fires and protects your home.

• Microwaves: A typical microwave oven uses 1,000 to 1,500 watts during operation. While this seems within range for a smart plug, microwaves also create electrical interference that can damage smart plug circuits. The high-frequency energy they generate can cause premature failure of the electronic components inside your smart plug.
• Coffee Makers with Built-in Grinders: Standard drip coffee makers might be okay, but models with grinders use motors that create high startup loads. The motor draws a surge of power when it first turns on. This surge, combined with the heating element, can trip your smart plug's overload protection or cause it to overheat.
• Electric Kettles: These convenient devices heat water quickly by using 1,200 to 1,500 watts of power. They run for short periods but draw maximum power the entire time they're heating. The concentrated power draw stresses your smart plug's internal components and creates unnecessary fire risk in your kitchen.
• Pressure Cookers and Instant Pots: Modern electric pressure cookers combine heating elements with electronic controls. They typically use 1,000 to 1,200 watts and run for extended cooking times. The combination of sustained high heat and long operating periods makes them unsafe for smart plug use.

5. Heavy-Duty Motor-Driven Devices

Appliances with electric motors present special challenges for smart plugs. Motors require a sudden burst of electricity when they start up, called inrush current or startup surge. This surge can be 3 to 7 times higher than the device's normal running power. Even if the motor runs safely after starting, that initial power spike can damage or destroy your smart plug.

• Window Air Conditioners: These cooling units use compressor motors that draw huge amounts of power at startup. A window AC might use 1,200 watts while running, but it needs 3,000 to 4,000 watts to get the compressor started. This massive surge will likely blow your smart plug's internal fuse or damage its relay switch on the first use.
• Refrigerators and Freezers: Like air conditioners, refrigerators have compressor motors with high startup loads. But there's another problem: food safety. If your smart plug fails or accidentally turns off, your food could spoil. The risk of foodborne illness and the cost of replacing spoiled groceries make this a bad choice for smart plug automation.
• Sump Pumps: These basement flood prevention devices must work reliably, especially during storms when you need them most. A sump pump failure can cause thousands of dollars in water damage to your home. They also have motors with high startup current. Never risk your home's protection by putting a sump pump on a smart plug.
• Washing Machines: These laundry appliances combine water pumps, drain pumps, and a drum motor. Each motor creates startup surges throughout the wash cycle. The frequent on-off cycling of multiple motors stresses your smart plug beyond its design limits and can lead to early failure.

6. Extension Cords and Power Strips

This might surprise you, but you should never plug a smart plug into an extension cord, and you should never plug an extension cord or power strip into a smart plug. This practice is called daisy chaining, and it's one of the leading causes of electrical fires in homes. Each connection point in the chain adds resistance to your electrical circuit, which creates heat.

• Why Daisy Chaining Is Dangerous: When you chain multiple devices together, you create weak points in your electrical system. Each adapter, plug, and socket adds a small amount of electrical resistance. This resistance turns electrical energy into heat. The more connections you add, the more heat builds up, increasing your fire risk significantly.
• Overload Risk Multiplies: Extension cords and power strips have their own amp ratings, usually 10 to 15 amps. When you plug these into a smart plug, you might accidentally exceed the smart plug's capacity by plugging multiple devices into the power strip. You lose track of the total power draw, which makes accidents more likely.
• Warranty and Insurance Issues: Most smart plug manufacturers specifically warn against using their products with extension cords or power strips. If a fire starts because you ignored these warnings, your homeowner's insurance might deny your claim. The manufacturer's warranty definitely won't cover damage from improper use.
• The Right Way to Expand Outlets: If you need more outlets, have a licensed electrician install additional wall outlets in your home. For smart control of multiple devices in one area, buy a smart power strip designed for that purpose. These devices have built-in circuit protection and are engineered to handle multiple loads safely.

7. Water-Based Heating Systems

Any device that combines water and heating elements needs special attention. These appliances pose dual risks: the electrical danger of overloading your smart plug, plus the added hazard of water damage or steam burns if something goes wrong. The combination makes them particularly risky for smart plug automation.

• Water Heaters: Whether you have a small under-sink water heater or a portable hot water dispenser, these devices use tremendous amounts of power to heat water quickly. Tank-style water heaters can draw 3,000 to 4,500 watts, while even small point-of-use heaters use 1,200 to 1,500 watts. Both exceed safe smart plug limits.
• Aquarium Heaters: Fish tank heaters seem small and harmless, but they run continuously to maintain water temperature. If a smart plug malfunctions and cuts power to your aquarium heater, your fish could die from temperature shock. Additionally, aquarium equipment gets splashed with water, which can damage smart plug electronics if water seeps into the device.
• Humidifiers with Heating Elements: Cool mist humidifiers are usually safe for smart plugs because they only use 20 to 50 watts. However, warm mist humidifiers use heating elements to boil water, drawing 200 to 400 watts continuously for hours. The sustained heat generation and humid environment create problems for smart plug reliability.
• Dishwashers: These kitchen appliances combine multiple dangerous elements: water pumps, heating elements for hot water, and heating elements for the drying cycle. They can draw 1,200 to 1,500 watts during operation. The combination of heat, water, and motors makes dishwashers completely unsuitable for smart plug control.

8. What You CAN Safely Plug In

Now that you know what should you not plug into a smart plug, let's talk about devices that work perfectly fine with these smart home gadgets. Understanding safe options helps you get the most benefit from your smart plugs without taking unnecessary risks.

• LED Lights and Lamps: Table lamps, floor lamps, and LED light strips are ideal for smart plugs. They typically use between 5 and 60 watts of power, far below the capacity limits. You can create lighting schedules, automate your home lighting, and save energy without any safety concerns.
• Phone and Tablet Chargers: USB chargers and charging stations use very little power, usually 5 to 20 watts. They're perfect for smart plug automation. You can schedule charging times to take advantage of cheaper off-peak electricity rates or prevent overcharging that shortens battery life.
• Fans: Standard box fans and tower fans use 50 to 100 watts of power. Unlike air conditioners, these fans don't have compressor motors, so they don't create high startup surges. You can safely automate fans for better air circulation and temperature control in your home.
• Entertainment Devices: TVs, game consoles, cable boxes, and stereo systems usually operate well below 300 watts. Smart plugs help you eliminate standby power consumption from these devices, which can save you money over time. Just make sure to turn devices off properly before cutting power to prevent data loss.

9. How to Calculate Device Safety

You don't need to be an electrician to figure out if a device is safe to use with your smart plug. A simple calculation tells you everything you need to know. Here's the step-by-step process to determine whether your appliance will work safely with your smart home setup.

• Step 1 - Find Your Device's Power Rating: Look for a label or sticker on your appliance. It's usually on the back or bottom. The label shows either watts (W), amps (A), or both. Some labels also list voltage (V), which is typically 120V in the United States. Write down these numbers before you begin your calculation.
• Step 2 - Convert to Watts if Needed: If your device only lists amps, you need to convert to watts for comparison. Use this simple formula: Watts = Amps × Volts. For example, if your device draws 10 amps at 120 volts, it uses 1,200 watts (10 × 120 = 1,200). This standardizes your measurements for easy comparison.
• Step 3 - Check Your Smart Plug's Maximum Rating: Look at your smart plug's packaging or manual to find its maximum wattage and amp rating. Most standard models handle 15 amps or 1,800 watts, but some cheaper units only handle 10 amps or 1,200 watts. Never assume your smart plug can handle the highest rating without checking first.
• Step 4 - Apply the 80% Safety Rule: Multiply your smart plug's maximum rating by 0.80 to find the safe operating limit. For a 1,800-watt plug, that's 1,440 watts (1,800 × 0.80 = 1,440). If your appliance uses less than this number, it's generally safe to plug in. If it's close to or above this number, plug it directly into the wall instead.

10. Smart Plug Safety Best Practices

Following basic safety guidelines protects your home, your family, and your belongings. These best practices come from fire safety experts, electricians, and smart home professionals who understand the risks and know how to prevent problems before they start.

• Buy Quality Products from Reputable Brands: Cheap smart plugs from unknown manufacturers often lack proper safety certifications and quality control. Look for UL (Underwriters Laboratories) or ETL (Electrical Testing Laboratories) certification marks on the packaging. These certifications mean the product has been tested for electrical safety and fire prevention.
• Check Your Smart Plugs Regularly: Once a month, unplug your smart plugs and inspect them for signs of damage. Look for discolored plastic, which indicates overheating. Feel the plug after it's been in use, it should be warm but never hot to the touch. Replace any smart plug that shows burn marks, melting, or unusual smells.
• Keep Smart Plugs Away from Water: Never use indoor-rated smart plugs in bathrooms, laundry rooms, or kitchens near sinks. Water and electricity create deadly combinations. If you need smart control in damp areas, buy outdoor-rated smart plugs with weatherproof enclosures and GFCI (Ground Fault Circuit Interrupter) protection.
• Follow Manufacturer Guidelines: Read the instruction manual that comes with your smart plug. Different models have different specifications and limitations. Some plugs work better with resistive loads (like lights), while others handle inductive loads (like fans) more safely. Understanding your specific model prevents misuse and extends its working life.