apples723 wrote:So ur saying a light switch has too much power?
No he's saying that if you don't know what you're doing you are a) going to fry your Raspberry Pi, b) going to kill yourself or c) burn your house down.
Start by learning to switch simple low voltage things like an LED with a 560 ohm resistor.
Move forward to switching relays (with transistors or opto-isolators), run the relay with a low voltage load (nothing more than 12-24 volts).
Because that prevents danger b) and danger c). It doesn't prevent danger a) as you can fry a Raspberry Pi with 24V but you won't be electrocuted or burnt to death.
Talk to a qualified electrician. Tell him/her what you're planning to do. He/she should be interested in preventing you from killing yourself.
There are also nice shiny things like 433MHz radio controllers that can be used for automating household electric circuits. You can look at using a Raspberry Pi to generate the control signals for something like that. For the United Kingdom there's the Energenie Pi Mote. http://www.raspberrypi.org/controlling- ... e-pi-mote/