Automated Switches: What should my wiring look like? (US Version)

So you want an automated hardwired light switch, but you’re not sure where to start. Well you’re in the right place. The most common requirement of any hardwired automated light switch is a neutral wire. Yes, there are a few…(read very, very, very few) switches that don’t require a neutral, but those will limit you to incandescent only. For those of us using LED, Fluorescent or some other energy efficient bulbs under 20w a neutral is REQUIRED!
So what does this look like?

This is a diagram of a switch with the neutral run directly to the light. This is not good for automated hardwired light switchs and i would HIGHLY recommend that if you want to automate the light, contact an electrician and have them pull a neutral for you. It’s not as expensive as you think and will save you lots of frustration.

This is a diagram of a switch with a neutral. The black “hot” connection is broken to turn the light on/off, the white “neutral” connection completes the circuit. The bare (hopefully) solid copper wire is the ground. It protects from static build up and from electrical insulation failure, in short it’s only job is to make your home safer. If this is what you see when you remove your wall plate you are a go for hardwired automated light switchs. YAY!

This is a diagram of what you’re automated hardwired light switch should generally look like when you are done. Yes there will be some slight differences on weather or not to pigtail (a short wire that leads from the switch to the yellow caps) the load and/or line but your ground and neutral should ALWAYS be pigtailed.

Ultimately, if any of this makes you feel uncomfortable or the wiring diagrams makes your eyes cross… CALL YOUR LOCAL ELECTRICIAN! They are there to help! Bad wiring causes fires and other glitchy weirdness you don’t want in your home. If connecting 4-5 wires excites your happy place, the term “pigtail” makes you giggle and electrical tape is your friend then… Let’s Get Wired Up!
I hope this help those on the fence… enjoy!


Very nice write up. I haven’t seen any switches other than a 3-way switch with the fourth wire. Does that mean a fourth wire needed to be pulled in this instance? Be it load or neutral pigtail?

Load and line are already there, they are the black wires that the switch uses the interrupt the flow of electricity allowing you to turn the switch on or off. Load is the “hot” run from the light to the switch and Line is the other half of the “hot” run from your breaker panel to your switch. Separating the two is important because wiring this backwards can cause an automated hardwired light switch not to work because the power is flowing in the wrong direction. Neutral is what brings the Juice, so with out it your automated hardwired light switches can’t power up and neither can your light. Regular switches just interrupt the flow of power so the only power they need is your finger :slight_smile: . So if your wiring looks like the first picture an electrician to pull that neutral down to the switch box is exactly what you need. This seams to be common not only older homes but also in switch boxes with only 1 switch. If you have more than 1 switch in the same box (2 or more gang) The neutral is normally there.
Also and this is very important, the wire color should be only used as a guide. Sadly there is A LOT of bad electrical work out there, ground is normally correct but everything else may or may not follow the color rules. Picking up a test kit (even if you return it after you are done) is a very good idea. So are pliers, electrical tape and those yellow caps.

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Just one note for clarification: all of the above excellent discussion applies only to adding one master switch to control a light. It does not cover the situation where you want to have two switches control the same light. In that case, normally you have one master and one auxiliary. In order for them to communicate to each other, there are different approaches with network switches. Two switches controlling one light is called a “three-way set up.”

For a three-way or four-way set up, the auxiliary and the master will commonly talk to each other over a “traveler wire” which is not included in the diagrams above.

An alternative that is possible in a networked set up is to just have the auxiliary talk to the hub and have the hub pass the messages to the master. In this case the auxiliary has to be powered, but it does not have to control the load to the light fixture. And it won’t need a traveler wire to talk to the master. So the auxiliary could even be battery operated sitting on a table.

Three-way and four-way set ups can be wired many different ways (from 5 to 8 depending on how you count), and not all of them work for networked switches. So that’s when things can get really complicated because it depends on the exact details of each wiring segment.

None of that is to take away from the excellent description in this FAQ. I just wanted to mention it because people who are looking for information about three-way set ups will need more than what is included in the FAQ on wiring a master switch.


I just start touching stuff together until it all starts working.

Haha JK. This is horrible advice. :wink:

There are some zwave switches around that don’t require a nuetral as well. So you don’t exactly need a nuetral but it does make things easier. I got these cause my wiring is from 720BC.

Food for thought

Cooper still makes a Z wave switch that does not require a neutral, but it can only control incandescents, not LEDs.

I think everybody else has discontinued the switches that don’t require a neutral because of the incompatibility with LEDs.

Even if there’s no neutral used at the existing switch, there’s usually a neutral somewhere. This is why an electrician can find one and bring it up in most houses that aren’t on the historical register. :wink:

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You may be kidding around… but that’s how i got my X10 home automation system going. I learned a lot like, what 110 feels like, what do circuit breakers do, the sound of bad wireing and that Alanis Morissette is actually god and she has a quirky sense of humor :smiley: . I totally don’t recommend learning how i did… but i know there will be a few who learn best the hard way. Its also why i don’t do 3-ways or 4ways, i started a small fire learning how those work with Insteon. When my Insteon network started dieing and i decided to rip it out i called an electrician to do my single 3-way correctly. Its still un automated.

We have something in common :wink:

110 feels nice on a saturday morning.

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Many Home Depot’s offer classes on how to install a light switch, and how to install three way switches. If you want hands-on learning, that’s often a better way to go then on your own house. :wink:

Oh i know, i was young, dumb and indestructible in those good ol Insteon days(for the record they were not that good just better than X10), and and so was my home apparently. I understand the wiring concepts, i get it’s just one more wire and not a big deal in the scheme of things. I even have an excellent book by Home Depot that covers 3-ways. When i hired and electrician to fix what i had done to my poor 3-way i found out that my wiring is not good. I have Neutrals from 2 different circuits that combine in the same gang box as the master of my 3-way. Until i get that fixed, i will always have an electrician do my 3-way.

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If you have the situation where you have live load to the light, I recommend you use an aeon dimmer or switch module and place it in the junction box where the light is located. Then the switch can be used as a passive toggle to the module. I’ve had two installations where this has solved this issue. The only downside is an on/off switch can get out of phase where up is off and down is on.

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The following video shows a Z wave light switch that doesn’t require a neutral (the GE switch in the video has been discontinued, but Cooper still makes one) tested with four different kinds of bulbs:

A conventional incandescent,
A conventional CFL,
A dimmable CFL,
And a white only dumb LED bulb

They didn’t test a smart LED.

Even in this very simple test, you can see the flickering problems with the CFL bulbs.

The plain white LED actually works pretty well, although not as well as the incandescent.

I still think it’s best to use a neutral wire, but it is possible if you only have the two wires available and you get the right switch and the right fixture and the right bulb.

We should also note that sometimes you’ll only see flickers at full on or below 25%, but not in between. There are many people who only dim between 50% and 90%, so they might not see flickers while someone else who uses a wider range does. This is why sometimes only one person in a household will complain about flickers.


Just wanted to mention that the advice about neutrals applies to devices made for use with US circuits.

European and Asian 230 VAC circuits generally don’t have neutrals at the switch, use different color codes, and are wired differently.

Vesternet, a European equipment retailer, has a brief article on this:

In the US, code for electrical devices requires that you follow the manufacturer’s directions.

The first rule for light switches and receptacles is that you never try to wire around the switch.

While it is tempting to think only in terms of “this switch turns on that light,” in fact all of the wiring is connected. You have to think in terms of the whole circulatory system. This is why wiring can get so complex.

One Consumer Product Safety Commission study of residential home fires found:

“In other fires, the connection between the neutral wire and the ground was inadvertently opened so that substantial currents were conducted through the BX, or armored, cable to other equipment that was independently grounded. The resultant overheating of the BX’s armor ignited combustible materials that were in contact with the armor.”

So an incorrectly installed switch in one room can end up causing a fire on the other side of the house. :scream:

If the manufacturer says the switch needs four wires (hot, load, neutral, and ground), then it needs 4 wires to operate safely. Don’t try to trick the switch by wiring two screws to each other (bootleg ground) or bypassing the switch altogether for some of the wires. It won’t be to code, but more importantly, you may burn out your new switch–or burn down your house.

Take pictures of the existing wiring before you disconnect everything. That includes pictures of the exact screws the wires connect to.

If you don’t understand what every leg of every connection is for, stop. Bring in an electrician.

Trial and error may be Ok when you’re building a potato battery for your 4th grade science class. It’s a very bad idea for house wiring. :fire_engine: :ambulance:

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2 posts were merged into an existing topic: Aeon Micro Smart Dimmer Install Help 3-Wire

Agree 100%, but just thought I would mention these so that just because a person doesn’t have a neutral at the switch gang doesn’t mean they need to give up on a lighting project. Switch loops are very common where the neutral is up at the fixture, and rather than have someone try to hack at it and endanger themselves or someone else, I just thought mentioning it would be of some help.

Carry on :smile:

Understood, and there are indeed many different ways to approach lighting projects.

The Aeons were already mentioned in a FAQ-type way in post 11.

There’s also the European wiring FAQ, which discusses relays since neutrals are typically not available.

But to brainstorm specific projects, it’s better to go to the device topic.

Dear Robert
Whats your recommendations for controlling LED with Z-wave switched without neutral???

Hey @JDRoberts,

Is there a general rule of thumb if a house has a neutral wire or not?

For example,

  1. year when the house is built?
  2. where the light switch box is installed?
  3. geographic?

US houses built from the 1980s on Usually have a neutral at the switchbox. Beginning in 2011, the national electrical code required a neutral at almost all switch boxes.

US houses built earlier than that may or may not. It just varies a lot.

European houses, including the UK, generally don’t have a neutral at the switchbox, although some do.

I can’t think of any particular reason why location within the home would affect whether there was a neutral or not.

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