Building new home - wire from light switches to ceiling light sockets? (Mexico)


I’m new to the world of smart devices. My wife and I are building a new home. I understand we should run A/C power to the light sockets in the ceiling, and we should run power (including neutral wire) to the switches. But I’m curious if there is any need to still have hot wire running from the light socket to the light switch, or if the switch can control the light completely through the hub and not require a wire between the switch and the light.

Basically what I’m hoping is we have power to all the light sockets and power to the switches, but to use the SmartThings app to link which switch controls which light and not have to physically wire the switch to a specific light socket.

I can’t believe how hard it has been to find an answer to this question :slight_smile: But it makes sense that many smart switches are designed to work with existing electrical systems.

Hope you understand the question. Thanks!!

What country are you in?

In general, you do need to still have a hot wire going from the wall switch to the ceiling fixture if you want to switch to be able to work even if your home automation system is off-line.

There are some safety code requirements that this be possible. In the UK, I think you have to do this with every primary switch, it’s only The accessories which can be done solely through network control.

In the US in most jurisdictions you are allowed to do this in many areas, but not all. It will also make your home much more difficult to resell in the future, just something to keep in mind. And not all building inspectors will approve it for a residential home even if technically it should be allowed by the code.

It also significantly limits your choice of equipment options. One of the most cost-effective ways to make a home smart is to use dumb lightbulbs and a smart switch. This works very well, but it does still require that there be a hot between the switch and the light fixture, because what you are automating is the switch turning on and off.

So I think the short answer is that well it is technically possible with today’s equipment, it’s not generally recommended. Instead, just use regular standard wiring to current NEC code (which will require a neutral at each switchbox) and that will give you the most options for the automation solutions which you will choose for yourself and what will be available to the home’s next purchaser.

You might have some specialty situations like outdoor garden lights where you wanted to do everything just through the network rather than with wiring, and that’s fine in most locations. But for just your regular residential lighting, I would go with standard wiring. It makes everything simpler as well as potentially saving you money in your home automation choices. :sunglasses:

Thank you for the informational reply! Very good points to consider.

We are from the US (San Francisco), but have moved to Baja California, Mexico. The property is 30 miles south of the last power pole, so we will be 100% solar. There is actually a small concrete block home on the property, but it has no wiring. So with the solar system installation I also need to run the wiring and this is how the question came up.

We are remote enough that there is no building code or inspections, although of course I will build everything as safe as possible. I suppose it’s not that much more difficult to run the wires to the lights, but I do like the idea of all network controlled.

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If you run your wiring in compliance with current National Electrical Code all will be fine and you will be able to adapt. Just because you don’t have a local code enforcement organization, doesn’t mean you shouldn’t do it correctly.

Time to buy a book:

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Each has electronics inside so they need power. But they don’t have to be wired one to the other (if both are smart). Just need to be powered. However, if socket is NOT smart, then you need to wire switch to socket.

While technically true, you CAN wire it that way - When building - consider that most people buying homes EXPECT a light to have a hardwired switch. It’s simply not common to wire switches and loads independently and not hard link them. So when building new you MUST consider that you will not always live there (a fact we often forget - especially in custom home construction) and another buyer may not actually want all the ‘smarts.’ They may gasp need it to go back to a stupid home. So for that reason - I tell people asking these questions:

Wire it traditionally, according to electrical codes. Always ensure there are neutrals in all boxes and request deep boxes in your install. If you have a ceiling fixture go ahead and use 14-3 instead of 14-2 romex (or 12 ga depending on the expected load / code) because someone may eventually want a fan up there. (It’s easy to tap off and tape the unused wire) Then modify as you need to to adapt to your smart devices. If you’re using smart bulbs and still need switches, then use devices like Inovelli’s devices that allow you to select whether the power at the load end is switched or not. That way you can pull out all the smarts and put in an ‘old fashioned’ chandelier and clicky switch to sell your house out in the woods to the luddite prepper who doesn’t want all that computer stuff spying on you keep it in for the tech mogul who does want it all…

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Thanks. I’m all for building to code for sure, even if I don’t have inspections here.

But does electrical code actually require a wire from a fixture to a switch? If I have a ceiling fan/light unit that operates via it’s remote control, I believe I can put an electrical box in the ceiling for it and not run a wire to a physical wall switch, right?

I also believe I can run power with neutral to a box on the wall and install a smart switch and still conform to electrical code as well…?

The national code in the US, which is just guidelines, does allow for fully automated lighting systems in most areas of the home (attics are an exception), but many townships override that.

However, when that was written the assumption was that the systems were all local systems and would operate as long as there was power and the system was not damaged.

Cloud dependent systems like smartthings are typically much more fragile (and smartthings specifically is), so it just doesn’t really make sense to rely only on that.

If you do run a hotline from the switch to the ceiling fixture you get the best of both worlds. You can still run all your lighting on an every day basis from your automation system. But if the system is unavailable, as smartthings usually is at least once a month, The switch on the wall will still work.

Also, first responders will be able to turn the lights on or off from the switch without having to know any of the details of your home automation system, which can save precious seconds in an emergency.

Also as I mentioned if you go to an automation-only system, it will cost you more, because you will have to have a smart device at the ceiling socket and a second smart device on the wall. If you have the hotline from the switch to the ceiling fixture, then you only need the switch to be smart. You can use regular dumb bulbs. That can be a significant savings when looked at for the whole house. :sunglasses:

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Excellent points again, JD!

Thanks for the thoughts and advice. You have convinced me to go ahead and just run the wire to the switch, it’s not that much more work and as you said, you get the best of both worlds!