Since home automation is coming our way now, which questions do we consider on topic and where is the line drawn. From an earlier meta question we already clarified that shopping advice is off topic. But what about software problems and hardware compatibility questions? What types of home automation questions are good here?
My own opinion is that we stay with the site's core audience, people that are handy with fishing wires, fixing plumbing, and swinging hammers. A question about how to install some home automation device and connect it to the house is on topic since they're dealing with cutting holes in walls, electrical wiring, etc, which has always been on topic here. A question that requires knowing an application, programming languages, or becomes product specific with hardware compatibility issues, is off topic.
Essentially, if you'd ask the general contractor, electrician, or plumber how to do it, it's probably on topic. But if you'd ask the local maker workshop, it's likely off topic.
I am new here, please excuse my effrontery, but I'd like to disagree with BMitch, in the part where he generalizes. I see the following main reasons:
1) As defined, this site is
a question and answer site for contractors and serious DIYers.
That definitely can include home automation. With its cost and aspects that need to be taken into account (like energy efficiency, home safety, interior design), home automation beyond sound controlled colour LEDs definitely is not for weak-hearted.
The core of this site is around parts of your home that are typically included when you buy or sell it, the structure, utilities, and major appliances.
Home automation overlaps at least with "utilities", and it is also often part of what one buys or sells a house with. We will probably see it getting more and more typical in the next few years.
2) This meta answer suggests that home automation is at home here. The comment of this site mod ChrisF to that answer kind of approves it.
3) Home automation so closely relates to other aspects of home improvement, that it would be difficult to separate them into two Q&A sites. Consider connected lighting, home security, HVAC control, solar panels, automated blinds, zero-energy buildings. I believe that the home automation SE attempt failed exactly for the reason that nobody cares about home automation disconnected from walls, floors and roof.
4) Contractors and electricians are more and more willing or forced to look into options offered by HA, at least here in Europe. I've just rented a very basic house with the boiler controlled via OpenTherm protocol. It's only a matter of time when programming them will be part of the normal heating servicing routine. At the same time, the usual energy meters are being phased out and replaced by the smart ones. The utility companies more and more offer, as part of the package, the internet-connected controls for your heating, to help optimize the energy costs.
To address the original question, I would say that the borderline should be somewhere around application of home automation to home improvement. Questions going too deeply into software or electronics and too far from the actual application to buildings may be moved respectively to StackOverflow and Electrical Engineering Stack Exchange, but shouldn't be closed.
In the end, this SE is the site for DIYers, and if lighting your home requires coping with the hiccups of connected LED lights, it should be at home here.