Electrostatic discharge with the case closed?

[the_servicer]

Most discussions of electrostatic discharge are about opening a case and handling internal components. But what about when a computer is just sitting there with the case closed? Are there are any common hazards? I'm wondering about possible precautions during handling, transporting, storing, and normal operation with the case closed.

 

[Nobu]

I've heard of people killing usb ports from large static discharges, but generally if they are grounded properly in the case (usually there is a ground wire soldered to the ports on cases with plastic panels, rear i/o shield has tabs which should thouch the outside case of the ports, and the mb and psu should be directly grounded to the case by screws, the psu connected to a properly grounded outlet) there should be no issues.

In a very dry environment, maybe touch something metal on the case (psu, fan guard/grill, etc) to drain whatever charge you have before plugging something in. There may still be a charge on the device you are plugging, but it should be much smaller, and case ground should handle it fine.

 

[Carlyle2020]

Each and every time i touch my case i get a electrostatic discharge due to my seat fabric. It's a faraday cage so who cares? I do refrain from french kissing my ports directly though.

 

[cpufrost]

When indoor humidity is very low (<25%), it's possible to build up over 50kV! This can arc 1/2" and if not discharged safely most definitely will wreak havoc with sensitive parts. Pulling new chassis' out of boxes packed in foam is one of the worst offenders! The shock can be painful. Fortunately the chassis keeps this out of the circuits.

Peripherals can channel enough energy to cause temporary effects (i.e. system freeze or spontaneously reboot). If there is any questionable ground (i.e. floating above chassis potential) arcs will basically put components at the same potential of breakdown voltage which is usually much higher than needed to do irreversible damage. Essentially any discharge sufficient to be felt or heard (snapping) is going to be destructive if it takes a path through sensitive devices.

The key to reducing ESD is ensuring you're always at the same potential as the part you're working on. NEVER use a wire connected to a wrist strap! Always use an approved lead with resistor. This is because of possible ground faults (hot chassis) and a direct wire will carry potential lethal currents through your body if that were to happen. A 1 megohm resistor will work fine in this case.