New to home automation -- How limited am I by old wiring?

If you have knob and tube wiring, In most jurisdictions it should’ve been noted on the inspector’s report, as many insurance companies will either charge you more or not insure a home with knob and tube wiring at all as it can become a fire hazard as it ages.

It’s not against code to have it in most US jurisdictions but you should certainly be aware that you do and probably have it inspected annually

But again, it would be rare to find it in a home that was built after 1940. But not impossible.

As far as the issue of neutrals at the switchbox, You may find that you have them at some switchboxes and not others. This is really common in a US home that was built in the 1950s. The reason is that over time people will tend to upgrade the electrical system one branch at a time or even one room at a time and you can end up with differing configurations. You’ve already seen this in your own house because you have some in wall receptacles that don’t have the grounding hole. So it’s probable that some were replaced but rather than doing the whole house at once, the homeowner just did them in the areas where they were immediately needed.

The following is an article from Insteon on how to tell whether you have neutral wires in the switchbox. The Insteon devices are not compatible with smartthings, but the article itself is good on the wiring part. We do need to say upfront, though, that US code does not mandate colors for most wires, and people can and do use any color, particularly if it’s near the end of the day and there’s only one spool left in the toolbox. So you might open the switchbox and see all black wires or even all red wires rather than one black, one white, and one red. That’s why the only way to really be sure is to use a line testing tool.

Also, about now I usually mention that if you live near a Home Depot many have a free course on how to install a light switch. Although it will not typically cover smart switches, it’s a very good way to get familiar with what the wiring will look like and how to use the simple tools for mapping your circuits. So it can be worth checking out If you like having that level of knowledge. Or, of course, you could always pay an electrician. :sunglasses:

No Neutral? The Lutron Option

If your switch boxes do not have neutrals, the easiest solution is just to use Lutron Caseta switches. Lutron Is an engineering company that only focuses on lighting. They hold a bunch of patents including one on a method for using a smart switch when there is no neutral wire. There is an official smartthings/Lutron integration which works well, although you do need to also have the Lutron SmartBridge Device to make it work.

These are very nice switches and an excellent retrofit solution for older homes. I use them in my own house Which was built in 1955.

There are a few Z wave switch models which don’t require a neutral wire, but they only work with incandescent bulbs and most people prefer LEDs or CFL’s these days.

You can get a Lutron starter kit with two master switches, two auxiliary pico’s (to set up a 3 way), and the bridge for right around $160. One bridge can support up to 50 Lutron devices.

So zwave switches will probably cost less Per switch, and you won’t need an extra bridge device, but they do generally require a neutral wire. So it’s just good to know that the Lutron is an option if you need it. :sunglasses:

Back to Smart Bulbs

One other alternative, as you noted, is a smart bulb and a smart switch cover. The smart switch covers come in a couple of different styles, But, yes, most of them just fit right over the existing wall switch.

The other very popular alternative is to get a battery operated device and either put a box cover over the existing switch and then put the battery operated device on top or put the battery operated device next to the original switch and just use a childlock on your original switch.

The following FAQ lists most of the devices that can work in this fashion. Some of the individual entries are battery powered and some are mains powered so read the entries carefully. There’s generally just one entry for each device and it should include a link to a discussion thread about that, so if you do have follow-up questions on any of the individual devices go to the discussion thread and ask the question there.