So I want to build a little "setup" with a led strip, using an arduino and a seperate psu to power the led strip. The psu outputs 12v 5A dc. Before I start connecting anything and might hurt myself, is the output of the psu deadly? I want to connect the the psu to the led strip through one of these: http://www.gearbest.com/diy-parts-components/pp_530107.html?. Any help would be highly appreciated. (Not very known with electricity)
12V won't kill you, unless you hook it to a sword and stab yourself with the sword.
As Oli Glaser answered on this question. 20V can kill you, but then you have to be very unlucky and unaware of your surroundings.
And as GreatScott has shown in one of his videos, he can handle around 60VDC and 20VAC. That's when he pushes his hands flat onto conducting plates => he tries to minimize the resistance.
But again, 12V will be safe. unless...
Also, you can lick the contacts of the 12V supply, it will sting a lot but you will survive, and possibly evolve into some lightning mutant from X-men. You'll be the next spiderman.
You can think of some rough figures and and calculate the power delivered to your body for eg. Under dry conditions, the resistance offered by the human body may be as high as 100,000 Ohms. Wet or broken skin may drop the body's resistance to 1,000 Ohms, as you can see where this sequence is going deep open wounds(as said by Harry above) can be more dangerous, so in conclusion you will be safe for 12v.