PC without ground from AC outlet?

[Screes]

So I'm in the process of modding a small case into a gaming rig. I came across a problem, not enough space for the AC power plug on the back of the case (the PSU is at the front of the case).

Then i remembered that my PS3 only has a 2 prong AC power plug, and doesn't utilize the ground wire. A PS3 is basically a small PC, so i thought maybe i could do the same.

I could probably fit the smaller 2 prong only AC plug on the back of the case. Is there anything inherently bad about doing this?

 

[Nenu]

Bad idea.
The PS3 is insulated so you cant get a shock if something goes wrong.

 

[Screes]

So the reason it's OK for a PS3 is because it's in a plastic case?

 

[Nenu]

Yes, they have taken care to make sure you cannot be electrocuted.
Its not something they choose to do, its the law if there is no earth connection.

See class II
https://en.wikipedia.org/wiki/Appliance_classes

Dont even think of removing the earth connection on a PC.
If someone else gets a shock, you are liable for their medical bills.
If they die, you will be prosecuted.

 

[plugwash]

So the reason it's OK for a PS3 is because it's in a plastic case?

It's not as simple as a plastic case. Even if you have a plastic case you will still usually end up with touchable metalwork connected to your electronics. For example various types of connector have touchable metal shells.

In an applicance with an earth the earth can be used as a safety barrier between "stuff that is connected to the mains" and "stuff the user can touch". This applies to the obvious stuff like live metal contacts but also to more subtle stuff like filter capacitors.

Switched mode power supplies need filtering components between input and output to prevent radiation of lots of RF noise. In a class 1 appliance with a mains earth connection the filter capacitors can be connected between the input and earth and the safety requirements (both in terms of leakage current and in terms of failure modes) on those capacitor are relatively mild.

In a class 2 appliance without a mains earth connection the filter capacitors have to connect directly between input and output and there is no earth path to take the leakage current. That means that both the leakage current through the capacitors (and hence the capacitors value) and the failure modes of the capacitors have to be carefully controlled.

As the power supply gets larger it gets harder and harder to meet both the EMC requirements (which want big filter capacitors) and the class 2 safety requirements (which want small filter capacitors). So most larger switched mode power supplies are class 1 and require an earth to safely separate the device being powered from the mains. I'm actually kinda surprised the PS3 slim is class 2, most laptops nowadays seem to have moved to class 1.