A friend of mine was asking about making a remote controllable breaker box. Like a web-enabled one that he could turn off his water heater, etc. with via his phone. With the ethernet shield, setting up the network interface and software would be really easy, but how would one control the breakers themselves? The first thing that came to my mind was controlling relays in-line with the circuit. Perhaps latching ones, so that they don't have to be constantly energized to remain in either state.
Is there a better way? Is running devices through relays all the time bad? Is there anything else I'm missing?
You won't control the breaker (which is a protection device not really intended to be switched a lot), you'd add a switch between the breaker and the device being controlled.
I use an SSR (solid state relay) to control a large electric motor with an arduino circuit. Relays are OK, but SSRs are easier.
Running devices via relay isn't bad at all - that's how lots of automated equipment is controlled. E.g., the HVAC unit on your house probably has several relays (aka "contactors") controlling the compressor, heating elements, etc. You will consume power keeping the relay closed (not sure how this applies to latching relays,as I've never used them).
You 'could' do it with an Arduino and ethernet shield, a lot of re-wiring, and large relays.
Even a small water heater will draw over 1 kilowatt of power ( about 4 amps for a 240 volt heater). Think large relays and large wires. I have never seen a latching relay that comes close to that power capability.
Don't get me wrong, I'm an Arduino fan but I recognize that some tools are better suited for a job than others. If you have the intellect to do this with Arduino, then doing it with Insteon will be a no-brainer, take less time, and probably cost much less.
The idea wasn't so much for turning on and off lights all the time as it was for turning on and off power in the house when you're leaving for an extended period. Like if you were going out of town for a couple weeks and you wanted to save power, but you wanted to come home to a non-sweltering house (florida) and take a shower right away.
I suppose that someone could simply wait for hot water (or get one of those tankless things) and flip the breakers yourself. The only other part would be the air conditioning, and thats easy to do with just the thermostat.