Outlet Without Ground

[geoffry]

Currently I work with an iMac plugged into a power bar with an adapter that allows it to go into an outlet without a ground (2 prongs).

I was worried about hurting the iMac but talked to an electrician a bit when I first set it up and he said the ground was to protect me if the device were to build up a charge.

The setup has been workign fine since June 13th of 2008 (I unplug the computer at night, just incase).

A question I have is if I brought a more powerful machine or a second machine to work and used the same outlet, would the risk of my components being damaged be higher?

Thanks in advance.

 

[Billb2]

No.

The Cliff Notes version:

The elctricity comes out of one side of the outlet, into one prong of the plug, then through the cord, through your computer , back down the cord, through the other prong on the plug and back into the outlet.

If there was a third, ground, wire, it would connect to everything metal in your computer. That way, if there was a short (ie. electricity went to a metal part of your computer) then that electricity would return to the ground (literally, the earth), the circuit would be overloaded instantly and a fuse/circuit breaker would blow and shut off the electricity.

Without the ground wire, if there is a short to a metal part of your computer and you were to touch that part, the electricity would try to flow through you. If you happened to be connected to the earth (ie, touch something metal that is grounded) the electricity would flow through you back to the earth, and you would blow, just like a fuse ot circuit breaker, except thay you cant be replacer/reset quite as easily.

Adding other devices to the circuit has no effect on the above scenarios.

I hope that helps.

 

[geoffry]

Thanks, I was sort of thinking the same thing but wanted a second or third opinion.

 

[magreen]

Right. This is one reason why lots of devices with no exposed metal can get away with only a two pronged plug. Since there's no chance you'll get shocked since its exterior is all plastic.

 

[Paperdoc]

Billb is right, that's the primary purpose of the ground pin - electrical safety in the event of an unplanned malfunction. But there's also a secondary function in electronics. Most such equipment has all its metal chassis parts connected to the Ground lead. In turn, cable shields and signal ground lines are connected to the chassis. Having all these connected to a real ground (earth) contributes to reducing (by shorting out) any noise or or signal leakage generated in the system. So a good ground can help reduce signal crosstalk within the device, and signal leakage to the outside world producing EMF "noise" in the surroundings. If the system you have now is working OK, obviously the noise issue is minimal. Adding another system with no decent ground just MIGHT (probably not likely, though) provide a new EMF noise source in the area.

 

[geoffry]

Thanks guys, I knew I could get some good answers here.

 

[Billb2]

And no one really talks about it, but eliminating EMF is part of the regimen for high end benching.
No UPSs, no GFIs and a solid, direct earth ground.