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Despite the ubiquitous nature of smart plugs currently available in the market, it can still be challenging to comprehend the complexities of intelligent control systems designed explicitly for devices that consume high amounts of energy. These energy-hungry appliances usually encompass devices like dryers, water heaters, central air conditioning systems, pool pumps, and electric stoves and heaters.

In this article, I dive into what the various options are for smart control of these appliances.

What is High-Load?

In this article, I refer to high-load appliances as ones that run on 240v circuits that typically require more than 15amps. For example water heaters and pool pumps.

If you are looking to smart control 110v (up to 15amp) appliances such as washing machines, refrigerators, microwave ovens, or freezers, then standard smart plugs like the Kasa Smart Plug (or for a Zigbee option, the Aqara Smart Plug) are generally capable of supporting the load.

However, there are examples where these plugs can fail over time, due to the high inrush current of the appliances on startup. In that case, the Zooz Zen15 is worth looking at, as it's designed particularly for large 15amp 110v appliances.

No matter what you choose, make sure to get a smart plug with overload protection and also double-check the power rating of the appliance against the smart plug.

Are there any High-Load 240-Volt Smart Plugs Available?

There are no high-load 240-volt smart plugs available in the US market.

I believe this is most likely due to safety concerns and the fact that most high-power appliances are hardwired or use specialized connectors. Since these appliances draw a significant amount of current, using a smart plug could pose risks, such as overheating if the plug is not specifically designed to handle the load. 

As mentioned, there is a much wider variety of NEMA plug connector types and market demand for such plugs is also relatively low in comparison to standard smart plugs.

There are a handful of 240v smart plugs on sale on Amazon, however, none of them can handle more than 10-15amps. They also have the standard NEMA 5-15 plug connector which is not designed for high loads.

Note: Working with high-power appliances and electrical systems can be extremely hazardous if not handled correctly. I always recommend utilizing the services of a professional electrician in carrying out installations or modifications as a licensed electrician can ensure proper installation, compliance with local building codes and safety standards, and prevent potential hazards. This article provides general information on ways to smart control these appliances but is not a substitute for professional advice from a licensed electrician.

Approaches to Smart Control High Power Appliances

The typical home will have a mix of hardwired and plugged high-powered appliances. From hardwired air conditioning systems and electric water heaters, to plugged clothes dryers and electric ranges. 

One approach is to replace your appliances with a smart appliance, however, that obviously costs a lot of money!

For high-power appliances that are plugged in, as there are no smart plugs available, you’ll need to have work carried out to hardwire the appliance to the circuit.

Then the hardwired appliance can be controlled by a smart switch.

There are ready-made smart switches for high-load applications from brands like Aeotec, Enbrighten and Sinope.

Alternatively, you can pull the relevant parts together to create one (such as a heavy-duty electrical contactor, protective casing, and smart relay/plug).

Note: Another option is to utilize a Smart Circuit Breaker (like the Leviton Smart Load Center). While these devices offer remote control, they are more suited to energy monitoring.

Option 1: High-Load Smart Switch

These smart switches are essentially electrical contactors with smart relays in a protective enclosure, that features a manual override switch, LED indicator, and an antenna for radio signals to get in and out of the case.

There are generally three types of switches, Wi-Fi, Zigbee, and Z-Wave. Below are some High-Load Smart Switches to consider after which I’ll get into the pros and cons of each network protocol to help you make a decision.

The Aeotec Heavy Duty Smart Switch is a device that can control high-power appliances wirelessly. It allows you to turn your appliances on and off from a distance and keeps track of your energy usage in real-time. The switch is secure and can handle up to 40 amps of current, making it a convenient and efficient tool for managing your powerful appliances.

  1. Remote Control: You can control your appliances from anywhere with the Smart Switch.
  2. Real-Time Energy Monitoring: The Smart Switch will show you how much electricity your appliances are using, so you can save money on your electricity bills.
  3. High Power Capacity: The Heavy Duty Smart Switch can handle appliances that use up to 40 amps of power, making it suitable for use with big appliances and electronics.

The Sinopé Electrical Load Controller is a device that helps you control the power usage of your high-energy devices. It works with Alexa, allowing you to use voice control through an Echo device. You can also use it with a smartphone or tablet by downloading the Neviweb app. The controller has different modes, such as automatic, manual, timer, and away, which you can use to manage your electricity consumption.

  • Voice control through Alexa with an Echo device.
  • Different modes to manage your electricity usage.
  • Personalized scenes available if supported by your Zigbee compatible hub and its application.

The smart outlet box is a device that lets you control your outdoor devices remotely using your phone or voice commands. It's a heavy-duty and waterproof box that's designed to protect your devices from the rain. You can install it easily using your existing wireless router, and there are no monthly charges to worry about. You can also share it with your family members. The device comes with a manual override switch, so you can turn it off in bad weather if you need to.

  1. Remote and voice control: You can control the device using your phone or voice commands through Amazon Echo or Amazon Tap.
  2. Waterproof design: The box is designed to protect your devices from the rain, with an easy-to-use manual override switch included.
  3. Compatibility: The device is compatible with your phone, Amazon Alexa, Google Home, and IFTTT.

This smart switch can control large loads like pools, pumps, patio lights, AC units, and electric water heaters. It's designed for both indoor and outdoor use, with a weatherproof metal casing and easy-access wiring. It's also compatible with Z-Wave, a wireless technology that lets you control your home automation devices remotely using your phone or tablet. With energy monitoring capabilities and clear LED indicators for power status, this switch gives you complete control and flexibility.

  1. Weatherproof metal casing with a lockable door for outdoor use and protection against tampering.
  2. Double-pole/single-throw switch supporting 120-277VAC and up to 40A for universal use.
  3. Energy monitoring capability for remote tracking of Watts and kilowatt-hours when connected to a compatible Z-Wave hub.

Suraielec's WiFi Pool Timer is a smart switch that you can use to control heavy-duty pool equipment and electrical appliances. You can control the switch with your smartphone using the Tuya Smart Life app. The switch is perfect for outdoor use because it is weatherproof, meaning it can handle sunlight, rain, and snow.

  • You can control the switch with your smartphone using the Tuya Smart Life app, which is easy to set up.
  • The switch has a weatherproof box cover that is resistant to rain, snow, and sunlight.
  • The switch has a simple interface that lets you set a schedule, countdown, or random timer to suit your needs. You can also share the settings with others.

The WiOn Wi-Fi Smart Box is a device that lets you turn on or off your outdoor electrical devices using your smartphone. It's like having a remote control for your devices, and you can use it from anywhere. The device has 12 settings that allow you to program when your devices turn on or off. It's great for heavy-duty devices like water heaters, pools, and pumps.

  • The device works with different voltage levels: 120V, 240V, and 277V.
  • The device is designed for outdoor use and has a lockable metal box to keep it safe.
  • You can use the device with your existing Wi-Fi network and a free app.

Option 2: Heavy-Duty Contactors + Smart Relay or Plug

As opposed to using an all-in-one heavy-duty smart switch, you can connect the various components together to achieve the same result. (In most cases, it’s easier to just use one of the above switches as it's not necessarily cheaper to pull them together individually)

Here’s a quick overview of how you can use an electric contactor to smart control a heavy-load appliance.

  1. The contactor is connected to the power supply and the heavy load appliance. The contactor acts as a switch, controlling the flow of electricity between the two.
  2. A lower-voltage smart device, such as a smart plug, smart thermostat, smart switch, or smart replay, is connected to the contactor's control circuit. This smart device sends a control signal to the contactor.
  3. When the smart device sends a signal to turn the appliance on, the contactor's internal coil is energized. This creates a magnetic field that pulls the contactor's contacts together, closing the circuit and allowing electricity to flow to the appliance.
  4. When the smart device sends a signal to turn the appliance off, the contactor's coil is de-energized. The magnetic field disappears, and the contactor's contacts separate, opening the circuit and stopping the flow of electricity to the appliance.

By using a contactor in this way, you can control a high-voltage, high-current appliance with a low-voltage smart device. This setup allows you to integrate the appliance into your smart home system and access features like remote control, scheduling, and energy monitoring.

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Here’s a quick diagram of this setup, courtesy of Elk Products. This is the Elk Heavy Duty Relay Contactor ELK-9200 solution which utilizes a standard 15-amp smart plug powered by a nearby 110VAC outlet to trigger the contactor to power a water heater. 

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ELK Heavy Setup

In this example, the 110VAC plug could be connected to a smart plug, like below.

More generally, electric contactors can also be triggered by a 24v smart thermostat, a 110v smart switch, or a 110v inline smart relay, such as the ones below.

It really depends on the power requirements of the contactor you use so double-check the power ratings of all devices you plan on using to make sure they’re compatible with each other.

A problem with using a wired smart relay instead of a smart plug is that radio signals may not penetrate the enclosure to get to the relay. That is why the smart switches in option 1 have integrated antennas.

The Elk example utilizes a standard 110v plug. This can be connected to a smart plug that is out in the open, for signals to reach it.

Should I use a Wi-Fi, Zigbee or Z-Wave Switch/Relay?

There are pros and cons for each protocol so it really depends on your requirements.

  • Wi-Fi offers easy integration, widespread compatibility, and familiarity but may suffer from network congestion, security vulnerabilities, and a shorter range. 
  • Zigbee provides low power consumption, mesh networking, and fast communication but requires a hub and may experience interference from other 2.4 GHz devices. 
  • Z-Wave also has mesh networking, a dedicated frequency, and a wide product range but also requires a hub and has slower communication compared to Zigbee. 

So consider compatibility, range, and interference when choosing a protocol for your heavy-duty smart switch.

Typical Load of High-Power Appliances in the Home

In the United States, several appliances and devices in a home are considered heavy power users. These appliances are typically on a 240v circuit as they tend to draw a significant amount of power. Here are some examples of heavy power users and a general idea of their power consumption:

  1. Central air conditioning system: 15-45 amps, 2,000-5,000 watts
  2. Electric water heater: 10-30 amps, 3,000-4,500 watts
  3. Electric furnace: 15-60 amps, 5,000-15,000 watts
  4. Electric clothes dryer: 20-30 amps, 3,000-5,000 watts
  5. Electric oven: 15-50 amps, 2,000-5,000 watts
  6. Electric range/cooktop: 30-50 amps, 3,000-8,000 watts

Types of USA Plug Connectors

Below are the most common NEMA plug connector used in the United States. The range from your typical NEMA 5-15 outlet (which is a grounded 15 amp) to the NEMA 6-50 outlet (which is a 50 amp connector used in ovens).

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Source: Wikipedia Commons


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