# Controling a regular residential 110V/15A circuit switch (or relay) from a PC

I am a software engineer by trade and also a rather skilled and well rounded (residential) builder with a special interest in wiring. I have rewired my entire two-unit house, panels included and seen it all.

In the course of home remodelling, I was wishing to be able to control every single electric control on every circuit in my house remotely using an Android app. To make that possible, I would need every single switch/thermostat to be upgraded into a relay and have cat5 cable run alongside every Romex cable to each control on one side and into a PC (or some other cheaper form of a CPU hosting device with a modem) which has a static IP online, on the other side.

Of course, that is a huge project, whose biggest parts would be making relays that can be controlled from a PC and writing software to control it all, web services, mobile app etc. So the first step in R&D would be to actually make something like that -- unless, of course, it exists already.

Is it possible to buy a relay that, on one side controls a regular 110V residential circuit, and on the other can be flipped using a PC?

A residential feature like this could be used to, e.g. report and control temperature at home remotely, turn the heat on 30 min before arriving home etc. You could even mount a web cam and watch your pets remotely.

• Is it possible to buy a relay .....flipped using a PC? YES Is it feasible, practical, reliable? NO , Not without enormous effort and fail-safe Normally ON relays not to mention humungous internal rewire job – Tony Stewart Sunnyskyguy EE75 Nov 28 '12 at 3:02
• of course, i am aware of the level of undertaking. i just think that wiring all residential controls and making them available online is the future of residential construction – amphibient Nov 28 '12 at 3:07
• Why cat5 cables? There are different possibly cheaper cables intended for that application. You can buy all the stuff as a whole product, but it's usually pretty expensive (as a top class product). – Al Kepp Nov 28 '12 at 3:16
• cat5 came to mind because it is data cable. you probably don't need 8 wires for this – amphibient Nov 28 '12 at 3:26
• You can find relays inexpensive here, but low voltage coils need >10x the current avail to most logic level outputs, so additional drivers or a custom card. digikey.com/product-search/en/relays/power-relays-over-2-amps/… – Tony Stewart Sunnyskyguy EE75 Nov 28 '12 at 3:28