Remote Light switch control

I'm working on a project to automate the lights in a detached building. I want to still be able to turn the lights on manually with a standard switch, but have the ability to turn them off remotely. I already have a networked project in the building, so this is simply an add on to the web interface. My question is in regards to relay types and a sensor.

I plan to replace the manual switch with a 3 way switch and use a relay as the second 3way. See here:

It would be nice to have a relay that switches it's state based on a single pulse and remains in it's state until a new pulse is sent. This way if power is lost, the relays position doesn't alter and it's not consuming power to remain in it's given state. I would imagine this sort of device exists, but I don't know what to call it. Can someone direct me?

The other issue with this sort of setup is sensing whether the lights are on or off. I could use a current sensor:


but I'm wondering if there is something a bit simpler that just sends a on or off signal.

The relay you want is called a 'latching relay'. One pulse closes it and another opens it. No holding current required.

Replace the manual switch entirely with one that goes to a spare Arduino input. Then the Arduino will always know the state of the relay and can switch on command when the local button is pushed. You could even use a traditional light switch to switch the 5V Arduino input. Just make sure all the low-voltage wiring is clearly identified and isolated from the mains wiring in the wall.

I've got about 5 of [u]these[/u] as well as some "appliance' relays, a programmable timer/controller, and a couple of manual remote controllers. (I didn't build any of this stuff myself).

The home automation switches (and dimmers) work locally or remotely. I can turn-on a light manually when I walk into a room and then turn it off remotely later (or vice-versa), or the programmed remote timer/controller can turn it off automatically, etc.

There a few different systems/protocols. [u]X-10[/u] has been around for more than 30 years and is probably the most affordable. (My system is a combination of X-10 and Insteon, which is X-10 compatible.)

DVDdoug:
I’ve got about 5 of [u]these[/u] as well as some "appliance’ relays, a programmable timer/controller, and a couple of manual remote controllers. (I didn’t build any of this stuff myself).

The home automation switches (and dimmers) work locally or remotely. I can turn-on a light manually when I walk into a room and then turn it off remotely later (or vice-versa), or the programmed remote timer/controller can turn it off automatically, etc.

There a few different systems/protocols. [u]X-10[/u] has been around for more than 30 years and is probably the most affordable. (My system is a combination of X-10 and Insteon, which is X-10 compatible.)

I’d like the arduino in control of the lights as the events it’s controls would benefit from that ability. These don’t seem to be something that can be controlled by an arduino.

MorganS:
Replace the manual switch entirely with one that goes to a spare Arduino input. Then the Arduino will always know the state of the relay and can switch on command when the local button is pushed. You could even use a traditional light switch to switch the 5V Arduino input. Just make sure all the low-voltage wiring is clearly identified and isolated from the mains wiring in the wall.

I have considered that, but the Arduino is 20 feet away from this switch. Moving it would require a longer network cable and longer wires to some of the sensors, it's connected to. If I use one of these:

http://www.amazon.com/10-Pack-Charger-Adapter-Samsung-Motorola/dp/B00PUXQ92A/ref=sr_1_12?ie=UTF8&qid=1440955287&sr=8-12&keywords=USB+AC+adapter

to supply the 5V power for a relay board, I only need s single conductor from the arduino to the relay. If I used a current sensor, the same applies. This would enable me to connect to the device with a bell wire pair. I could also use a second AC to USB adapter as a tool to provide an indication that the power is on instead of the current sensor. As the building is steel, grounding everything is no problem.