I just ordered a hub. I plan to add a water sensor and some other items. I also have a basement hallway light that is controlled by 3 differently located light switches. I see the light switch kits, but I think these are for single pole/swithc applications. Is there some sort of smart kit that I can use that would control this basement hallway light (that has 3 different switches)?
There are smart switches that have add on switches to control the main switch. The switches typically require a neutral and the add ons require a hot and traveler.
As @rontalley mentioned, networked switches are wired somewhat differently than non-wired switches. There will be a single master switch which controls the load for the light. Then the auxiliary switches will be of one of two types. A few brands, notably GE and Leviton, use physical traveler wires Between the auxiliary and the master. Physically pressing the auxiliary switch sends a pulse message along the traveler to the master, which then controls the load. I know the GE can handle up to three auxiliaries, I honestly don’t remember whether it can go higher than that, but that would give you four switch positions.
Other brands use “virtual three ways” where the auxiliary has its own network radio and sends a wireless message either to the hub or to the master switch itself. So the auxiliary essentially acts as a wall-mounted remote control for the master. With the ones that send a message to the hub you can have as many auxiliaries if you want, anywhere you want in the house.
In either case, you must typically replace all the switches, not just the master, in order to get networked control. And you must choose auxiliaries which are designed to work with that specific master.
( There are two brands which will let you use the network master switch with an existing dumb auxiliary, but you still have to rewire everything in order to get it to work right, so it’s almost the same thing. But we can save that for detailed discussion.)
So the short answer is that there are a number of different models which can solve the use case that you describe, although they may solve them in different ways, and you should assume that you will need to replace all of the switches, not just the master.
You can read more about wiring in the following thread. Although the thread title is about three ways, four ways are also discussed.