4 Smart Switches That Work With No Neutral Wire

My house was built in 1909. I can still see 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.

If you’re already confident that you know all you need to know about your wiring, you can read the next section where I have my recommendations for smart switches that work without a neutral.

However, if you’re unsure about some of the wiring side of things, you can continue reading past the recommendations. The bulk of this article explains what you need to know about neutral wires with smart switches.

What are the best smart switches that work without a neutral?

Like many others, I’m still searching for a “no-hub-required” smart switch (that means WiFi) which a) works with no neutral and b) is LED friendly. Even though I haven’t found the perfect smart switch that works with no neutral, I did find the following products that work.


Lutron Caseta Dimmer Switch

Right now, the Lutron Caseta Dimmer switch is the best I’ve found.

Read more: Lutron Caseta Review

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 bundle like the starter kit below.

Also, make sure you get the Lutron dimmer switch. The standard Lutron switch (this one) will not work without a neutral.


Broadlink TC2

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.


Yoswit BlueTooth Smart Switch

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).


Inovelli Z-Wave Dimmer Switch

Lastly, Inovelli has a Z-Wave dimmer switch that will work with no neutral. It was just released and last I checked it was sold out. Once I get a chance to review it, I will update this with a mini-review. Remember, since it is a Z-Wave switch, it will require a Z-wave compatible hub.


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.

A typical home in the United States has high voltage electricity (13.2 kV which equals 13,200V!) coming into the home. Before the electricity can be used, 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).

electrical diagram showing typical step-down transformer for U.S. homes

The transformer converts the incoming 13.2 kV electricity down to 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:

  1. Connect A to neutral = 120V
  2. Connect B to neutral = 120V
  3. Connect A to B = 240V

Most wiring in your home is either 1 or 2 (120V). 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 and a neutral wire. So, how can it be that some switches “don’t have a neutral”?

The easiest way to explain it is to answer the following question: Does the line voltage go to the switch first or to the light bulb first?

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).

electrical diagram showing standard switch with neutral wire
The line voltage goes to the switch first, then to the light (has 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.

electrical diagram showing standard switch with no neutral wire
The line voltage goes to the light first, then to the switch (no neutral)

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.

electrical diagram showing smart switch with neutral wire

Smart switch with no neutral

Now let’s take a look at the second configuration (no neutral) with a smart switch installed.

electrical diagram showing smart switch with no neutral wire

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 power the light. They will usually be colored one black and one white. The third wire should be the ground wire and is usually colored green or bare wire.

Switch box with no neutral

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 (see the Wyze bulbs below).

The main problem 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.


Final Thoughts

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.

Eric Blank

Eric Blank blogs about smart homes and other connected technology here at thesmartcave.com. He enjoys technology, sports, outdoors, and dabbles in the dark realm of politics. He dreams of someday living in a castle on an island but for now will settle for smalltown, USA.

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Stephane Boisjoli - a couple of months ago Reply

It seems everyone misses the obvious: Don’t put the controller in the switch box. Get something like “Micro Switch G2, DSC26103-ZWUS, by Aeotec with Pigtails”, put it in the light box, and it will control the light. Now, the problem I haven’t figured out is what kind of controller to put in the light box to switch the light. It may help to re-wire the switch to not actually switch and just provide the box with power.
(When I used X10 stuff, they had a purely wireless switch [no wires at all], but I don’t know if that exists in the smart home environment yet).

    Eric Blank - a couple of months ago Reply

    At that point, why wouldn’t you just buy a smart bulb?

      Tim - last month Reply

      When the fitting has multiple bulbs, or when the switch controls multiple fittings. Ie Chandelier type with 5 candle bulbs, or multiple recessed lights in a kitchen (12 bulbs in my kitchen, all switched on together)

Andrew P Mulder - a couple of weeks ago Reply

What about when I have a 240/220V switch (for baseboard heater) with 2 hots, a ground and no neutral? I only need a switch for this, not a thermostat.

Thanks!

David - a couple of weeks ago Reply

Another option is Insteon Remote Control 2-Wire Dimmer Switch. This switch doesn’t require a neutral but you will need the hub too.

    Eric Blank - a couple of weeks ago Reply

    Yes. However, I don’t think it works with LEDs. I could be wrong about that though.

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