Oh, no, no neutral, now what!

I’ve been slowing upgrading all standard switches in the house to automated switches made by TP-Link. Until today the upgrade was going smoothly. Forty-one devices have been installed as of today. I’ve ran into an unexpected situation while attempting to install two additional switches. There isn’t a neutral wire in the switch box. Unfortunately the TP-Link’s require such in order to work.

The two rooms I wish to control are on the ground floor. I’d like to control them from an upper floor - lights on/off during the evening. I’m certain the TP-Link single pole switches are out of the question. What I’d like to know is;

  1. Have you run into a similar issue and;
  2. How did you solve it?

Regards

I’m pretty sure most smart devices are going to require a neutral wire because of the components inside them. That being said, I know Lutron makes some switches in the Caseta line that do not require a neutral. You may be able to use that coupled with their bridge. I do realize that’s a deviation from your TP-Link plan, but they do integrate with home-assistant it will be a lot easier than running a neutral wire (trust me)

Shelly has the Shelly 1l that doesn’t need a neutral line, and is pretty small so hopefully would fit behind the existing switch. Not available yet from Amazon but just a matter of time.
There are zwave no neutral solutions, but then you would need a zwave controller.

Do you know if you have conduit in the walls? If so, an electrician can pull a neutral from the neighboring load possibly.

There are some zwave relays that do not require neutral. I use these, inside wallbox, in the few areas with no neutral. The switches were removed and just wall plate blank.

I controlled these with alexa(voice only) but recently added a zwave switch, connected to nothing, and use the on/off of that switch to trigger on/off or the relay controlling the lights/fan

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Any smart switch will require a neutral, dimmers generally don’t. If you can get away with using a dimmer instead then there are options such as the Aeotec Nano Dimmer however this means Z-Wave rather than WiFi. (my Z-Wave devices seem to be faster responding than my WiFi ones though, they are awesome)

That’s something I’m capable of. Unfortunately there’s no conduit. Drywalled with NMD90 cable installed.

I’ll check those out. Thanks

Surely they can get an extra wire down a drywall.

This might work. Since posting I have discovered this option. As you state, these types of dimmers are mainly for use with tungsten bulbs. The house is new, all fixtures are LED. I think the Shelly route may be best.

Thanks for your thoughts

The Aeotec definitely works with LED lights

Hello. One solution would be to install the tp-link switch but use home assistant to pass the switch state to a wifi relay that could be installed behind or inside the light fitting. Sonoff basic for example. Then the wire going from the light fitting to the switch can be reterminated so it has a permanent live and a neutral instead of permanent live and switched live.

It has been said already it’s not true. Shelly 1L for example

That’s an interesting idea. I’ll give that some thought.

Through a hollow wall isn’t too difficult. The big question is: where is the wire coming from?

If the base of the wall is accessible from the basement or its top from the attic then fishing a new wire can be a fairly straightforward and neat procedure.

Without this kind of easy access, we’re looking at a lot of ‘drywall surgery’.

Honestly, running just a neutral wire alone sounds hacky and I’d be surprised it it conforms to the NEC so that’s why I’ve never implemented it. When faced with a ‘switch-loop’ circuit, (where the mains runs to the load and then to the switch thereby not provisioning it with a neutral wire) I have permanently disconnected the mains from the load and run a new cable from the mains directly to the switch. In effect, you alter the circuit’s order from:

mains->load->switch

to:

mains->switch->load.

I couldn’t agree more! Having worked in the electrical field for many years, I can’t begin to tell you how many dangerous “short-cuts” I’ve seen. The worst I remember is installation of an outdoor light on the soffit of a house. The install was not to code, no junction box. Instead a small hole was cut through the aluminum and a wire passed through it to a light fixture. This left the aluminum siding rubbing against the wire which, through vibration caused by wind, eventually cut through the wires insulation. This in turn energized every piece of aluminum siding around the house, making for a very dangerous situation. Needless to say the owner was quite shocked (literally) when he arrived home and attempted to enter the house by way of the screen door. It was only luck that saved him from being electrocuted.

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Fortunately, I’ve only encountered these two:

  1. Wires spliced with wirenuts without being enclosed in a junction box.
  2. Invisible junction box.

First case was encountered while renovating a basement. I removed the existing suspended ceiling and discovered someone was too cheap to buy a J-box and just spliced the wires in “mid-air” (not even any kind of makeshift strain-relief).

Second case was accidentally discovered while checking a 3-way light circuit. The switch at the top of the stairs had old wiring (circa 1960’s) its counterpart at the bottom of the stairs had new wiring. The reason is because they removed part of a wall at the base of the staircase that housed the lower switch. They had to move the switch’s location and that meant extending the existing circuit. That means there’s a J-box buried in the wall somewhere between the two (or hopefully a J-box and not a "mid-air’ splice).

FWIW, my favorite are pictures (posted in some other Internet DIY forums), of wires protruding out of a J-box with the caption:

Are any of these a neutral wire? What should I do?

… call an electrician.

This will not affect many people but I live in a VERY old house. Be aware that the switches and other devices that do not require a neutral DO require a ground. I think they get around the neutral requirement by being under the current limit to ground (probably intended for things like GFCI’s). For my kitchen light I ended up installing an in-line Sonoff switch for the light (not really up to code either) and mostly using the existing switch. But I have to leave it on if I want to control it from HA. In other places I have just used Wi-Fi bulbs and again have to leave the switch on.

The devices that indicate they don’t need a neutral typically allow a ‘trickle current’ to flow through the load in order to keep their electronics powered.

To be clear, the lack of a neutral wire at the switch isn’t a cause but a symptom. It indicates the mains runs directly to the load and not the switch. In other words, if you inspect the load you’ll find it is provisioned with a neutral. This kind of circuit is sometimes known as a ‘switch loop’ (the ‘loop’ is the wire running from the load to the switch). Extending a neutral wire from the load to the switch would be … hacky (and nearly impossible to fish from a ceiling light to a wall switch without cutting open the drywall).

Those disgusting things aren’t even legal at all in Australia!