I have a single pole switch with 4 lights, that I want to replace with a 3-way switch. Power currently runs to the switch. I don't have a way (without drilling a lot of holes, which is really not an option) to run 14/3 wire to the desired location for the 2nd switch. Is it possible to add the other 3-way switch to the end of the light run without rewiring all the lights with 14/3. What would that wiring scenario look like? If not feasible, what are my other options?
Smart Switches to the Rescue
There are a lot of different smart switches available as solutions. The methods I know of to handle "3 way" switching with smart switches are:
- Piggyback on existing 3-way wiring
This works well if you have existing 3-way switches but want additional features such as multi-location dimming or remote control. Does not help you
- Piggyback on regular wiring
Some smart switches can use regular wiring in a more flexible way by sending signals over the wiring instead of simply switching between wires. That might help you here, if you can run a cable from the other end of the lights (which it sounds like you may be able to do), this may be an option.
Note that this does not necessarily mean WiFi. There are a number of different wireless systems available. A typical smart switch system that includes WiFi capability may have the WiFi part connected only to one "main" switch with the other switches "talking" to the main switch via a different protocol. So security is a concern but you may not actually need to connect your switches to a potentially vulnerable WiFi network in order to get wireless capability.
The big advantage of the 2nd switch being wireless is no wires to run, at all!. The disadvantage, of course, is the need to change a battery periodically. But modern devices are incredibly low power and your particular situation sounds ideal for this solution.
There are plenty of choices. One example (I have no connection to the company in any way) is Lutron Caseta. According to the FAQ page, the Pico remotes are designed to last 10 years on a single battery.
Be careful though - make sure anything you get is UL Listed (or equivalent). While the remotes are harmless, the "main" switch will be hooked up to 120V (US) or 240V (elsewhere) and you don't want to take chances on "substandard" items.
Let's see how practical this will be with old style 3-ways. Diagram out how each of the lamps and switches will be connected with cables. No triangles are allowed - you must do a "tree" topology. And note where power comes in.
Now along those cable paths, let's draw some lines.
two yellow lines between the two 3-way switches. These will be travelers.
a "white" (let's use blue) line amongst all these points: Power source, every lamp, and one of the 3-way switches. This is neutral.
a "red" connecting to every lamp and one of the 3-way switches. This is switched-hot.
a "black" connecting power source to the other 3-way switch. This is always-hot.
Plus grounds connecting everything.
All of these wires must be in the same cable. If you need 5 wires, you are not allowed to use a /3 and a /2.
Now, in some segments, you will have 4 or 5 wires includng ground. Cables with that many wires can be had, but they're pricey.
The perfect situation is when one 3-way switch is an endpoint spur off the other 3-way switch. At that point, the cabling is very practical. So you can have it logically wired like that, but physically the /3 cable from switch 1 travels via all the lights - it just doesn't stop and enter their junction boxes.
As you can see, this is a mess of drywall and sawdust.
As Manassehkatz and ThreePhaseEel are advising. One smart switch replaces a plain switch, and the other one is a wireless remote. This is the only sensible answer.