Is Grounding a Necessary Safety Measure for Electronic Power Supplies?

[LordVader88]

I have a nice and neat little PSU with a fuse from a DVD player, it outputs +/-12, gnd and +/-5 so 24 , 17 and 7 as well.

The PCB had a 2 prong AC plug, probably with one bigger than the other. And on the PCB there is a place where a 3rd ground prong would be screwed on like on my printers PSU , and it is copper traced to several things.

I soldered on a 3 prong cable/plug but never hooked up the ground prong, what would happen if I did?

Would it be bad or good? I've done high school physics and 1st year university physics, so there's a mountain I still need to learn now that I'm back into electronics.

Is it that 1 of the 2 prongs acts as ground, so don't hook up the 3rd prong, its already safe enough to use (I was using it in a flashlight, but now I have a LAMP hung from the ceiling!, so I can use it for a bench PSU again)

 

[vk6kro]

If the power supply and whatever it is powering are enclosed in a plastic box, then it doesn't matter if you ground the metal parts of the circuit for safety reasons, although it may be worth doing for other reasons, like noise pickup or radiation.

If there are metal parts that can be touched, it would be safer to ground these. This is so that in the unlikely chance that something breaks down and these metal parts become live, then current will flow to ground via the ground wire and blow a fuze before you touch it and get killed.

It is good insurance to use proper grounding and local safety laws probably demand it.