4 Smart Switches That Work With No Neutral Wire
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My house was built in 1909. It still has pieces of the original knob and tube electrical wiring nailed to the floor joists in the basement.
Thankfully, the electrical has been updated since then.
Unfortunately, I still have a few switch boxes that don’t have a neutral. That means that the vast majority of available smart switches won’t work in those boxes. However, I scoured the internet and found some that will.
3 options if you don’t have a neutral
If your home has switch boxes without a neutral, you basically have 3 options.
1. Add a neutral
Adding a neutral requires adding an additional conducting wire between the fixture and the switch.
It can be done, but pulling wires through finished walls can be a real pain, especially if you don’t have the proper tools. You could certainly hire an expert to get the job done, but it will cost you.
2. Leave your switches alone and buy smart bulbs instead
Most experts recommend switches over bulbs. But if you want easy installation and widespread smart home compatibility, buying bulbs may be best. Plus, smart bulbs are actually getting pretty cheap, especially if you’re happy with plain white bulbs.
The main problem (here’s how to solve it) with using smart bulbs is what to do with the existing switch? When someone decides to use the wall switch to shut the light off, the power to the bulb is cut, which means it will stop being a smart bulb until you turn the switch back on.
3. Buy a smart switch that works without a neutral
There are a couple smart switches that work without a neutral. I haven’t found the “perfect” switch yet, but there is at least one that’s really good (hint: it rhymes with neutron).
It’s more expensive than your typical smart switch, but the extra cost is still probably significantly less than paying a professional to pull some extra wires through your walls.
Also, if you buy a dimmer switch, make sure your LED bulbs are specifically labeled “dimmable”. Otherwise, you may end up with some flickering problems.
What are the best smart switches that work without a neutral?
Here are my two main requirements for a no neutral smart switch:
- Works with no neutral – Well, duh.
- Works with LEDs – Any smart switch I install needs to work with LED bulbs. I quit buying incandescent bulbs years ago.
Believe it or not that narrows down the field quite a bit. There are a few other smart dimmers that work with no neutral, but I didn’t list because they don’t work with LED lights.
Lutron Caseta Dimmer Switch
Right now, the Lutron Caseta Dimmer switch is the best I’ve found.
I know it’s the same one that everyone else recommends, but it’s the only one that supports dimming, LEDs, and easy smart home integration.
Lutron uses their own wireless communication (Clear Connect) so it will require a Lutron hub. It’s very reliable, even with many devices. If you haven’t bought any Lutron products before, the best way to save a little money is to buy a starter kit bundle.
Also, make sure you get the Lutron dimmer switch. The standard Lutron on/off switch will not work without a neutral.
Inovelli Z-Wave Dimmer Switch
Inovelli has a Z-Wave dimmer switch that will work with no neutral. It was just released (Fall 2019) and I just began testing one. I will put out a full review soon, but so far all I can say is, WOW!
This may be the best smart switch available anywhere.
This thing is packed with features. You can control multiple scenes, smart bulbs, and even setup smart notifications using the onboard LED. The setup takes a little more work than the super-simple Lutron system, but these Inovelli switches are sooo much more powerful from a home automation standpoint.
NOTE: These do require an extra part (Aeotec Bypass) if you use them with no neutral and the load is less than 25W. Most single LED bulbs are under this threshold. If there are multiple bulbs in the fixture, the total load is the sum of the load of all bulbs.
The Broadlink TC2 switch is a lower-cost alternative. It will work without a neutral and can handle LED bulbs as well. It becomes an exceptionally good deal for 2-gang and 3-gang applications.
However, it’s not a dimmer switch (just an on/off switch) and it does require a hub. It works with the Broadlink Pro hub which supports voice control and a growing list of smart home integrations.
A lesser known company, Yoswit, also makes a smart switch that works with no neutral. It has the potential to be a really nice product. However, it connects via BlueTooth, so the smart home integration is weak (for now).
What is a neutral wire?
If you’re going to be installing your own smart switches, you will be working with some potentially dangerous wires, so it’s probably a good idea to know what you’re dealing with so you can avoid making a stupid mistake.
In order to fully understand what a neutral wire is and why we have it, you need to have a basic knowledge of how our homes are wired.
Typical electrical transmission lines in the United States have high voltage electricity (13.2 kV which equals 13,200V!). Before the electricity can be used in your home, it needs to be converted to a lower voltage. This is done using a device called a transformer (represented by the squiggly lines in the image below).
NOTE: Alternating current (AC) does not have polarity. Instead, it has phases. I used the + and – symbols to represent the different phases.
The transformer converts the incoming 13.2 kV electricity down to a usable 240V. Notice that the voltage difference from end A (+120V) to end B (-120V) of the transformer is a total of 240V.
Also notice the transformer has a line coming from the center which has a voltage of 0V. This is the neutral. Since the neutral has a voltage potential of 0, it is significantly safer to work with than the “hot” wires A and B.
Looking at the diagram above, you should be able to see there are three ways to create a circuit:
- Connect A to neutral = 120V
- Connect B to neutral = 120V
- Connect A to B = 240V
Most wiring in your home is 120V (either 1 or 2). Certain applications that require a lot of power, such as a stove, are usually wired for 240V (3).
What does it mean when a switch has no neutral?
According to the previous section, every 120V circuit in your home has both a hot wire (A or B) and a neutral wire. So, how can it be that some switches “don’t have a neutral”?
To HAVE a neutral, we want the line voltage to come to our switch box first. Then, from the switch box another loop goes out to the load (light bulb or whatever). The diagram below shows this configuration (this circuit HAS a neutral).
The case that everyone refers to when they say “no neutral” is when the line voltage comes to the light bulb first. Then, from the light bulb, another loop goes to the switch. This is shown in the diagram below.
Both circuits work just fine when you only have a standard mechanical switch. However, you run into a problem when you have a smart switch.
Why is no neutral a problem for smart switches?
In the diagrams below, the dotted rectangle represents a smart switch. R1 represents the load required to power the smart switch. That means there needs to be power running through R1 at all times. Otherwise, the smart switch will be unable to power it’s wireless communication.
Smart switch with neutral
Below is a diagram of a smart switch installed in the first configuration (with neutral). Notice that regardless of whether the switch is on or off, there is a clear path from line to neutral that includes R1.
Smart switch with no neutral
Now let’s take a look at the second configuration (no neutral) with a smart switch installed.
Again, regardless of whether the switch is on or off, there is a clear path from line to neutral that includes R1. However, in this case the light needs to be included in that path. That’s not good because we need R1 to be on all the time but we don’t want the light to be on all the time.
The key to creating a smart switch that works without the neutral loop is to make R1 the perfect resistance. R1 needs to restrict the current enough so that the light bulb doesn’t turn on when the switch is off. At the same time, it needs to let enough current through so that the switch can power itself.
If it were as simple as making R1 the correct resistance to make sure the light can’t turn on when the switch is off, it would be a fairly simple problem to solve. However, due to complexities caused by AC power, it’s not a simple problem to solve when it comes to powering LED bulbs. That’s why the options are so limited for smart switches that work with no neutral.
How do you know if you have a neutral?
I just explained it above using diagrams, but if you’re not used to looking at wiring diagrams, it’s probably clear as mud.
Here’s an easy way to check:
If you open your switch box and you see two white wires joined with a wire nut (not connected to the switch), you can be fairly sure your switch has a neutral loop. You should be good to go with any smart switch.
A switch box with no neutral loop will usually only have three wires (see image below). Two of the wires will be the current carrying wires that power the light. They will usually be colored one black and one white (potentially with black stripe). The third wire should be the ground wire and is usually colored green or bare wire.
If you have switch boxes without a neutral wire, there’s no need to panic. Several manufacturers have come up with smart switches that solve the problem. And, if none of those are what you’re looking for, there’s always smart bulbs.