3 way switch no neutral

Ultimate Smart Switch Installation Guide

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Installing a smart switch is easy. The first step is to choose a brand that works well for your home. Then, follow these steps to set up your new smart switch.

If you want to learn what the smart switch does first, you can review our “Consider Your Smart Home to be Your Helpful Roommate!” post.

Smart Switch Neutral Wire FAQ

Can I install a Smart Switch without a neutral wire?

Yes, you can! Smart switches that can be mounted without a neutral connection are available in the market. 

Actually, almost all smart switches need a neutral connection, only Single-Pole Smart Switches can be connected without a neutral wire.  

Of course, now some brands have started to release 3-way Smart Switches and 4-way Smart Switches that you can connect without the need for a neutral wire.

However, do not forget to cross-verify the features of the product you want to buy, as there are many and a wide variety of Smart Switches on the market.

What happens if you don’t have a neutral wire?

We know that we need a neutral for the circuit to be completed and for the equipment to work. If you do not have a neutral wire, the circuit is most likely completing itself over the ground wire. 

4 wire

Is it OK to use the ground as neutral?

Ground cables are not designed to pass the current needed by the circuit. It is placed to transmit fault currents and residual currents that will pass through the circuit to the ground. For this reason, it is not correct to use the ground as neutral.

4 wire neutral

Do you need a neutral wire at every switch?

“When wiring lighting circuits supplied by a grounded general-purpose branch circuit, the 2011 NEC now requires you to provide a neutral conductor at nearly every switch point [404.2(C)].”  (EC&M) 

For an ideal circuit, you legally need a neutral wire for each switch. It will be correct to bring neutral so that the correct electrical protection can be made. 

However, since pulling an extra cable for each switch increases the construction costs, the neutral cable is not brought to the box behind the switch as a general acceptance, especially for single-pole switches.

Do smart switches work with normal bulbs?

Smart switches can work with normal lamps. It will solve all your on/off and scheduling needs for incandescent, halogen, LED, and fluorescent bulbs.

The dimming issue is a little more complicated. It would be best to choose your Dimmer Smart switch according to the type of your lighting product.

Because the principle of dimming each different type of bulb is different.

Do smart switches work with normal bulbs?
Source: Feit Electric

How Do I Install A Smart Switch?

There are several ways to install a smart switch, depending on the installation point. On this page, we’ll explain how you can install a new smart switch instead of the old switch by removing the old switch from the box on the wall. Note that a smart switch connection is no different from a normal switch connection.

The first step is to remove the old switch from the wall box. There will usually be two wires coming out of the switch: the line and load wires. These wires connect to the terminal screws on the back of the switch. 

Remove the screws and pull the switch out of the wall. Now you need to determine which wire is the neutral wire if you have one. 

Look inside the wall box for a white wire that connects to the screw terminals on the back of the box. This is your neutral wire. 

Now that you know how many cables you will be connecting with, you can look at the options below which are suitable for you.

How to Wire a Smart Switch with no neutral?

Installing 3-Wire Smart Switches (No neutral smart switch)

3-Wire Single-Pole Installation

A Single Pole setup means you install a switch that controls a circuit and a set of lights.

This guide will show you how easy to connect  3-Wire Smart Switches and no neutral smart switch dimmers.

3 wire smart switch
Source: Cync Support

3-Wire 3-Way Installation

A 3-way setup means you install two switches(one or both must be smart switches) that control a circuit and a set of lights. In other words, a switch that shares the control of a light with another switch. 

The following connection method is valid for both 3-way dimmer switches and 3-way normal switches with no neutral required.

3 wire 3 way smart switch

The most important point in 3-way switch assembly is to understand which is the line cable and which is the load cable.

Because, as you can see from the circuit drawing above, traveler cables only complete the connection between the two switches. In order to complete the circuit and light the lamp, the necessary line and load cables must be properly labeled during the disassembly process.

3-Wire 3-Way Smart Switch Installation Guide by Cync

For this, when you take your old switch out of its box, you can find out which one is the line cable by turning the fuse back on and using a voltage tester. When the switch is in the off position, you should see energy in the line cable and not see it in the load cable. When you turn on your switch, you should be able to see the presence of energy in both the line and load cables on the voltage tester.

And since you will assemble two switches for 3-way installation, you will see that there is a voltage on the line cable of only one switch. You can call the box with the voltage “line side box”. The other one will obviously be the load-side box.

We go to all this trouble because I don’t think it’s right to say “here’s the line wire”, trusting that the wire colors are correct. Sometimes when we open the box, we can only see black wires. I strongly suggest you do this little voltage test as well to avoid possible electrical shocks or equipment damage.

Although it looks like you need a Neutral wire when you look at this circuit, you won’t have to deal with a neutral wire at any point in the connection.

3-Wire 3-Way Other Switch installation types

When you opened your switch box, you did not see a neutral cable and if you do not think that the connection type is the same as one of the 2 ways I explained above, there are two more connection types you should look at. 

There are detailed explanations about these two connection types on CYNC’s support page. I leave the links on the connection types.

How to Wire a Smart Switch with neutral?

Installing 4-Wire Smart Switches (Neutral Required)

4-Wire Single-Pole Installation

The only difference between a 4-wire single pole installation and a 3-wire single pole installation is that the neutral wire in the box is also connected to the smart switch.

4 wire smart switch
Source: Cync Support

4-Wire 3-Way Installation 

This type of connection is very similar to a 3-wire 3-way. The only difference is that there is an extra neutral cable again. It allows light to be controlled from 2 switches.

4-Wire 3-Way Smart Switch Installation Guide by Cync

4-Wire 4-Way Installation 

We have seen that 1 pair of traveler cables are circulating between the switches in a 3-way connection.

Note that 2 pairs of traveler cables will increase in the 4-way 4-wire switch connection, and the number of traveler cable pairs will increase in the multi-connection.

The connection you will see behind any switch in a 4-way connection will be as follows.

4 wire 4 way smart switch
Source: Cync Support

4-Wire 3-Way Other Switch installation types

When you opened your switch box, you can see a neutral cable and if you do not think that the connection type is the same as one of the 3 ways I explained above, there are two more connection types you should look at. 

There are detailed explanations about these two connection types on CYNC’s support page. I leave the links on the connection types.

Pro tip: If you plan to use the smart switch for ceiling fans or shades, I suggest you check the suitability(Power/Amperage) of the smart switch you will use on the product page. Since most smart switches are only produced for lighting control, they may not be suitable for or capable of controlling ceiling fans.

Pro tip 2: In some brands; While it is sufficient for one of the 2 switches to be a smart switch in a 3-way connection, some want to replace all switches in the same circuit with smart switches.

Pro tip 3: If you think that you can’t find the right connection method according to the explanations above, Lutron has a very successful and user-friendly tool in this regard. I recommend you to check it out.


I think there are 2 things that complicate the Smart switch connection:

  • Whether or not there is a neutral cable,
  • Cable labeling (3-way,4-way, or multi-connection types) before removing the old one if there are more than 2 switches controlling the same lighting.

And it is very important to choose the right smart switch by looking at the connection types I have explained above. 

Do not forget to visit our Smart Home Wiring page for wiring solutions.

Batu of CondoChance Team

BSc. Electrical Engineer & MBA
10+ years of industrial experience as an Electrical Engineer

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