USB drive shocks me: bug or feature?

I’ve got an USB drive, and I’ve noticed that whenever I touch the metal casing of the plug and I’m grounded (by touching the radiator of the central heating) I get a small shock.

Link to an amazon page with the bugger

I’ve read that the USB slot delivers 5 volts of power (current? I forget) to devices, so it may very well be my own fault for touching the plug (or not using the outer plastic casing, which means the whole stick is electrified.)

However, should this happen, or is there someting seriously wrong with my hardware?

I’m assuming this is with the drive plugged into the computer? If this is the case, you’ve likely got a grounding problem, either inside the computer or in the electrical wiring inside the walls. Do you get shocked from touching the computer case, too? The USB hub provides 5 VDC, not enough to produce the sensation of an electrical shock under normal circumstances.

Yup, with the drive plugged in. I just tested, but none of the metal parts of the case seem to be ‘hot’. However, one of the contacts of the USB socket (nothing plugged in) seems to be electrified. Nothing too painful, just a tiny bit unpleasant.

You shouldn’t be able to feel it at all. The low end of sensation for voltage is about 30 V, give or take, under normal circumstances. There shouldn’t be anything like that kind of voltage from the USP port; if you’re feeling it, there’s a serious problem. There could be an isolation problem in the computer’s power supply, for example. This means that your power supply outputs could be at or near rectified line voltage. The circuitry only cares about the voltage difference between the +5 V and neutral lines, so if the neutral is at 120 V and the +V is at 125 V, there is still only a 5 V difference, which is what is expected. BUT, there is also the ~120 V difference between the outputs and Earth ground. This won’t affect the computer’s operation, but it can certainly affect yours. Do you have a voltmeter you can run some tests with?

You mention that the house has a radiator. This makes me think that it’s an older house (not necessarily a valid assumption) and that you might have 2 prong AC outlets. Is the computer perhaps plugged in to a 2 prong to 3 prong adapter? If so, did you connect the ground on the adapter to an earth ground?

It’s also possible that the hot and neutral wires are reversed in the outlet.

How are normal circumstances determined? I’ve had 3V battery block melt some wires right into the palm of my hand and you bet I’ve felt that. There is a chance the strands pierced my skin prior to the melting and such so that might be ‘abnormal’ circumstances.

I’m not sure what you’re describing here. Did the wires short across the battery terminals? If so, you betcha that can melt insulation and fuse wires. The voltage may be low, but depending upon the type and configuration of the battery, the current can be quite large in a dead short. I’m going to say what you felt probably wasn’t the electricity, per se, but more likely the heat caused by the current flow.

Any kid with a PP3 battery knows that’s not true :wink:

Sticking that on your tongue is NOT normal circumstances. :stuck_out_tongue:

So you mean I shouldn’t investigate electrical problems with similar tactics? :eek:

Houston, we have a problem. :wink:
Your computer and peripherals should be plugged into a surge protection power strip equipped with a 3 prong receptacles with supply cable plugged into a 3 prong grounded receptacle.
In addition there may well be an internal problem with the PC MB and/or the power supply.
Nothing about the externals or the connections should cause a shock between you and a ground such as a radiator of water pipe.