Hello I found these project online its called vent a garage. It has 2 ac fans the LINK DEPOT 120mm AC Cooling Fan (AC-FAN-1238B) and its controlled by a thermostate. What I have plan is to use the arduino and a temperature sensor to turn on the fans when for example reaches 70 degrees. what I dont know is what to use to link the 2 ac fans to the arduino to communicate.
these are the spark fun instructions
https://www.sparkfun.com/tutorials/119
But I do agree, If your not familiar and comfortable working with mains voltages, GET HELP, knowledgeable help, professional help if needed. 
THIS CAN KILL YOU IF NOT DONE RIGHT 
You get to do things right as long as you do them right, in many cases you get to do things wrong only once...
I hate it when tutorials provide advise that is less than SAFE.
The above is WRONG.
1. It needs to be fastened and NOT floating around.
2. The wires should not be soldered before entry into a compression style connection, as if there is any heating the solder retract and the connection become poor.
it either makes it worse or potentially hazardous.
3. they don't show any form of cable clamp to stop it getting pulled out the box.
4. The board design leaves a lot to be desired.
They are relying on a clearance across the pcb of slightly under 2mm ... it should have a physical cut between the track carrying mains voltage and the relay coil.
(they have put the low voltage side on the other side of the pcb which is wise)
I agree with the other replies.
If you are unfamiliar with this then remain unfamiliar and buy something like this which can be controlled remotely from an Arduino.
Mark
I hate it when tutorials provide advise that is less than SAFE.
The above is WRONG.
1. It needs to be fastened and NOT floating around.
2. The wires should not be soldered before entry into a compression style connection, as if there is any heating the solder retract and the connection become poor.
it either makes it worse or potentially hazardous.
3. they don't show any form of cable clamp to stop it getting pulled out the box.
4. The board design leaves a lot to be desired.
They are relying on a clearance across the pcb of slightly under 2mm ... it should have a physical cut between the track carrying mains voltage and the relay coil.
(they have put the low voltage side on the other side of the pcb which is wise)
I agree with the other replies.
If you are unfamiliar with this then remain unfamiliar and buy something like this which can be controlled remotely from an Arduino.
Mark
Agree with most points.
For strain relief, there is built in strain relief on the box, if you look carefully you will see it In the picture
Top left corner, it is north American box and outlet. NOW the strain relief is not meant for a box left floating un attached. It is for when it is mounted on a stud and with drywall etc around it so in this case it will not be adequate, this is a common misunderstanding over here
should be something more like this
or something from this set of images appropriate to your region https://www.google.ca/search?q=power+cable+strain+relief&espv=2&tbm=isch&tbo=u&source=univ&sa=X&ei=LdPnU-uNLIyYyASGsoHwA…
The socket is good for USA and Canada, not UK or Europe or pretty much any other country (You know what your sockets look like.
Also, if your going to do this, don't do this board, it is not worth it and as MCB pointed out, it has issues
This one from Spark fun is not expensive, seems to be designed much better and has appropriate cable connectors suitable for the job
Oh and going solid state all the way with something like this https://www.sparkfun.com/products/11042
https://www.sparkfun.com/products/13015
This unit requires nothing else, you can control it directly from an Arduino or any other micro-controller, as it only needs 3V to energise and will take up to 32V. It can easily screw into any box it fits into
Regards
peter
Peter
I agree that is a much better solution ...well done.
I have heard that there are some solid state relays using "... less than optimal parts ...." inside, so its is wise to run them at full load then remove the power and check if they get hot.
The markings make them look like a genuine thing, but they are apparently a poor copy.
The true test of any of these is the 1000v DC ( megger ) check between any of the Mains side and the low voltage control side and the metal mounting plate.
For those interested element14 has these ( on special for NZ$122 ).
Mark
