Single pole vs double pole: what’s the difference?
Brad Pretty, 3 years ago   |    7   |    4 min read   |    30381

Often overlooked, the methods used to wire thermostats into your house and heaters play a huge role in the reliability and performance of your whole heating system. While the different wiring systems predate the smart technology era, they have become especially important since the advent of the smart thermostat. Some smart thermostats (Nest, Ecobee) help to regulate a central heating system, like a furnace. These are commonly referred to as low-voltage systems. While these types of systems service the majority of the households in the northern US and Canada, there’s still a sizeable number that uses other options: baseboard heaters and other electric space heaters. These are known as line-voltage or high-voltage systems and traditionally are controlled in two different configurations: Single Pole Thermostats or Double Pole Thermostats.

Powering a smart thermostat uses a relatively small amount of energy, but how it draws this energy can make a huge difference in how your device performs (or if it even works at all).

How High-Voltage Thermostats Work

[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_single_image image="236" img_size="full" alignment="center"][vc_column_text]Traditionally, there are two separate ways to regulate a high-voltage heating system. The first and simplest way is a Single Pole Thermostat. This thermostat consists of a switch that’s always “on” – meaning it maintains a closed circuit between your electrical panel and heater. In this case, your heater is always “live”: there’s current passing through it. SIngle Pole Thermostats often rely on a rechargeable battery that is charged by the excess energy of the live feed whenever the heater is turned “off” – and that’s a problem. This process has been termed “power-stealing”, and places the reliability of your whole heating system in the hands of a single tiny battery, prone to failure from overcharging and repeated use. It’s especially a problem for modern smart thermostats utilizing a battery based system, as they require a larger amount of energy to operate and take longer to charge. In this system, turning the heater off completely means the battery will die and the thermostat won’t function at all, so it requires the whole heating system to remain on at a low level at all times in order to charge – obviously not ideal for energy saving.[/vc_column_text][vc_single_image image="235" img_size="full" alignment="center"][vc_column_text]The other option is a Double Pole thermostat. A more complex setup (4 wires are required) allow for the power to be switched off completely. Unlike the single pole setup, the power supply of a double pole isn’t directly tied to the heater – it’s powered by a separate circuit. No batteries, no “power-stealing”. There’s a switch in the thermostat that completely shuts off power to the heater. This means that when it is set to 0°C (32°F), it is actually off, unlike Single Pole Thermostats, two wire thermostats. For non-smart thermostats in line-voltage systems, this is the most energy-efficient option.

The Age of the Smart Thermostat

We expect innovation out of our smart hardware, but in a lot of cases, these smart devices are being installed in homes with a more traditional power setup. There’s no one-size-fits-all option – power set-ups differ from house to house. When it comes to line-voltage setups, however, there’s really only one option for a Smart Thermostat – Mysa. Mysa brings smart functionality and control to high-voltage systems in a way that has never been done before.  Its smart features ensure that you get the most control from your home heating by learning and maintaining your heating routines. There’s also remote access through the Mysa app, meaning that you can control your thermostat from just about anywhere in the world. It can also integrate with your Apple Homekit, Google Home, or Amazon Alexa. (Which one is best for you? Check out our comparison article here)

Technically speaking, Mysa has been designed to use the best aspects of the traditional line-voltage power setup. It’s a Single Pole thermostat, but it doesn’t have the drawbacks of a battery – instead using a dedicated circuit powered by a neutral wire. It also differs from your traditional Single Pole in that it can actually be set to zero. With a dedicated power source, there’s no battery, no “power stealing”, and no reason for the thermostat heating system to cut in unless you program it to do so. While it is constantly “live” like all Single Pole Thermostats, that just means you have to turn off the breaker before you work on it – which is always a safe move. With sensors in the thermostat itself, it allows for monitoring without activating your whole system. This means that it is more reliable and more efficient than traditional thermostatsMysa can likely replace any high-voltage thermostat up to 3800W or less, but it is best to check here before you make a purchase. It’s best that you get a professional to help with the installation, as the process can be complicated with a polarized wire setup. Here are some helpful installation guides! With the advent of smart technology, it’s important that it integrates into our life in a sensible way. Instead of retrofitting your entire household in order to take advantage of the latest (potentially costly) breakthroughs, think about making your existing home heat setup more efficient. About 1 in 3 households in Canada and approximately 7 million in the Northern US can benefit from Mysa. Is yours one of them?[/vc_column_text][/vc_column][/vc_row]


  1. Mark

    How is MYSA a single pole thermostat? I have two wires only for my thermostat (single pole) which isn’t compatible with MYSA. Would love to buy a MYSA for four rooms but not willing to try if the compatibility test is only asking for my email with no plan for true single pole support.

  2. Murray Atherton

    I’m looking for the blog post that I was directed to I your app for thermostats that I my have 2 wires and a ground. Where is that article hiding????

    1. Brad Pretty

      We’ve made some changes to our blog and support over the past few months and it’s possible wires got crossed or the article got removed. You can contact our support team for more answers!

  3. Mark Zandberg

    I am in trouble. 🙂 I hired an electrician to rewire the house with one outlet box (above a light switch) dedicated for a future thermostat to control a heater on the wall. Drywall followed. I bought a heater and I ordered the Mysa (beautiful device). I opened the cover to the thermostat box in the wall and found six wires (2 ground, 2 black and 2 white that were covered in black electrical tape). One set of these wires (ground, black and white w/tape) was marked “Line”.

    I have been trying to find my electrician but he appears to have left the state. I normally wire up outlets and switches but I suspect I’ll toast my Mysa thermostat if I cross any of these lines. This looks and smells like a double pole scenario.

    1. Brad Pretty

      Hey Mark,

      Please get in touch with our support team at and they’ll be glad to help you determine the best way to install Mysa. Sounds like it is compatible, but you definitely need some professional input.

      1. Mark Zandberg

        I did. They were great. Problem solved quickly. They went way above and beyond my expectations.

        I love this device.

  4. Anna

    Interesting post, Thanks for sharing.

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