The Right Relay

[Zaktt]

Hello, im trying to start my own project for controling some lights and tvs, computers and my ac in my house. i plan on using a relay to control everything i jut dont know what the relay has to be rated for, i know max amount of amps that can go thru a u.s wall outlet is 20A @ 120V. do they make a 8 or 16 channel relay board that is rated that high? is there a better way to do this? thanks 

[jack wp]

Most appliances do not need 20 amps. There are some that use a lot, like AC, electric heater, electric stove.
I suggest you check each appliance you want to control, to determine its rated amps (or watts). Then only pay for high power relays where you need them.
For example, a 60 watt light bulb uses one half amp.
A TV will be about three amp.
10 amp relays are common, and easy to find. they come on a board of one, up to I think eight. I have some that have one, two, and 4, that work well.
Of course, if you were going to control the AC, I guess you would use the low power controls, that are attached to the thermostat.

Good luck.

[Chagrin]

An appliance that uses 20A will have a plug where one prong is perpendicular to the other (not parallel). The receptacle, if it's 20A rated, will similarly have one side that looks like a "T" so it can accept both 15A and 20A plugs.

[Zaktt]

Thank you so much that answers my questions thanks

[drjiohnsmith]

hoe automation is farily off the shelf, and mains electricity is interesting if you get it wrong.

X10 is one of the 'standard' home automation protocoles, and there are plenty of mains interfaces to X10 , lets you concentrate on the fun bit, the code,

http://en.wikipedia.org/wiki/X10_(industry_standard)

http://arduino.cc/en/Tutorial/x10