USB Power Surge/Device shocked me on touch

Thanks, do you have any advice as to how to ground myself when I sit down at my desk?

Would touching my metal desk frame be enough to ground myself? Or the metal filing cabinet next to me?

bitplayer said:

Thanks, do you have any advice as to how to ground myself when I sit down at my desk?

Would touching my metal desk frame be enough to ground myself? Or the metal filing cabinet next to me?

Ether would be fine

Grounding yourself by touching something only works if that "something" has an electrical path to earth ground. Your desk might have a path to ground if there is a grounded metal plug strip bolted to the desk. I doubt that the filing cabinet would be grounded in any way.


In cold, dry climates, your body can build up a lot of static charge. The actual voltage is not easy/cheap to measure (nor does it really matter much). That is why you will see websites claiming vastly different voltages that static charges can reach in a human. The expensive equipment used to test products (like cell phones) can generate 30,000 volts to be sent into the phone. Humans walking on carpet can generate more than that and it really hurts when you discharge that much static electricity into a grounded object (e.g. some door knobs).

To prevent the pain of those extreme static discharges, the path to earth ground needs to have some resistance to slow the rate of discharge. Think of the path to ground as being a water hose. Think of the resistance as being a valve in that water hose. If the valve is all the way open, then water (electricity) is going to flow relatively fast. If the valve is almost all the way closed, then water (electricity) is going to slowly flow thru the hose (wire).

If the path to earth ground has the correct resistance (to prevent pain), then it should take about 3 to 5 seconds to discharge the static build up in your body. Humans - being the impatient creatures that they are - tend not to want to wait those few seconds.


You can buy expensive discharge mats to place under a keyboard. Those mats generally come with a wire that plugs into the ground part of an electrical outlet (in your case, the APC unit). That wire and/or the mat itself should have resistance built in. However, it is cheaper (uglier?) to move your APC unit to a location where you can touch a grounded part before touching your computer/controller.

What model APC unit do you have?

APC Back-UPS® ES 550VA 8-Outlet Power-Saving UPS (BE550G)

This is the unit I have. both monitors and the computer are plugged into the batter back up slots.

Bummer. That APC model does not have coax connectors that are grounded and easy to touch:

So, considering I dont have one of those, what would you suggest?

Do you have anything (like a desk lamp) that is metal and uses a 3 wire plug?

No. My desk lamp is 2 pronged. I suppose I could just plug in an extra PSU and place it on the back corner of my desk.

That is the sort of thing that you need to touch. A grounded, unpainted metal object.