Benno_fra_dk:
Here we go:
Dropbox - Error - Simplify your life
Dropbox - Error - Simplify your life
As you can see, the center pin in one end of the relay is the "Hot" pin - it has almost no seperation from the low voltage parts!
http://www.smokeandwires.co.nz/469-thickbox_default/5v-relay-srd-05vdc-sl-c-10a.jpg
For starters, clean the board with mineral spirits (Husholdsningssprit) & an old toothbrush - clean both sides.
Now, connect the cleaned board up to power and Arduino, and place the relay-board on something insulating (a piece of paper etc.)
My best guess is that it works. Try it out and return with your findings.
Anyhow, those relay-boards looks dangerous, with that minimal spacing between "Hot" and lov voltage side.
// Per.