Kin junior is walking around a lot now a days and he likes to touch and lick everything.
Tonight he started putting his little fingers into the USB and firewire ports on my PC, so I shooed him away, but are these ports dangerous? I’m thinking of covering these up anyway, but would be nice to know.
it is low voltage and not dangerous.
it would not be a bad idea to cover all jacks and ports to keep Kin junior from sticking things inside then and breaking costly electronics.
there was a very good tv commercial with a VCR and a kid with a sandwich.
the power pin of USB delivers 5 volts, which is not a shock hazard. Firewire ports can deliver anywhere from 8 to 33 volts DC; in most systems it’s 12 volts (also not a shock hazard) except for some older Mac desktops which had a 28 volt power supply rail.
either way, the design of the ports is such that it’d be difficult to touch any of the contacts with only a finger- even ones as small as a toddlers. You might still want to cover them if only to keep him from sticking stuff in there you might not be able to get out.
hadn’t thought about that one in years. It was always good for a laugh. Thanks.
Covering them to protect them from sticky fingers is a good idea. You can buy silicone port covers for all your ports. Alternatively, just chop the ends of dead / surplus cables.
And get used to saying, “That’s not a toy.” 
Firewire? You need a new computer.
Gotta love those kids:
These could, of course, be considered choking hazards. Heads they win; tails you lose.
If you have kids small enough that you’re worried about them putting their fingers or toys into computer ports, I wouldn’t leave cut off USB plugs sticking out of your computer (or silicone plugs). That would be a choking hazard.
(And if I had read the entire thread…)
The key issue is that they are DC voltage. Low DC voltage isn’t going to shock you like AC will. You can grab a car battery’s terminals with both hands and nothing happens (and that’s 12V and several hundred potential amps). Even with the car running and charging. As far as sticking a piece of metal into one, I suppose there’s a small risk of a burn from it heating up, but I think you’d fry the motherboard and the power supply would trip off before that.
total nonsense. it doesn’t matter what the “potential amperage” is. the “potential amperage” is the current the source can deliver if the load resistance is low enough. 12 VDC is as harmless as 12 VAC. there isn’t enough electrical potential (voltage) to push enough current through a human body to be a danger. a car battery can dump a thousand amps into a dead short, but if I grab both terminals with my hands it isn’t going to do shit because the resistance of my body is too high.
put simply, the danger zone for electrical shock is between 100 and 200 milliAmps through the heart. this range of current can kick the heart into ventricular fibrillation. you need sufficient voltage to be able to “push” that much current through the heart. in the right conditions, 120 volts is enough to do that.
It isn’t “total nonsense.” The low internal resistance of a car battery allows it to dump hundreds of amps into a dead short. That’s not true of a 12v pager battery…
it’s nonsense because your body is not a dead short. You all need to familiarize yourselves with Ohm’s law. volts, ohms and amps are all interrelated. a car battery can dump a thousand amps into 0.1 ohms. It won’t even push a trickle through the thousands of ohms of a human body.
OK, to be utterly correct.
A car battery is however dangerous, simply because it has such a low internal resistance, shorting one out will usually lead to whatever is doing the shorting out melting or vaporizing. This can lead to very nasty burns. They are not safe to leave around kids.
However pretty much any low voltage supply or device is safe. They do not provide enough voltage to deliver either a shock to a human, or are able to deliver enough current to be a hazard if shorted out. Typically they will either shut down or blow an internal fuse if they are shorted out.
There is a danger zone - 50 volts DC is - with some bad luck involved (ie wet skin) - able to cause heart fibrillation. Speaker terminals of high power HiFi amplifiers are curiously one place to find this. The power supplies inside power amplifiers is somewhere to be very careful - there is both voltage and current delivery capability to cause anything from electrocution to serious burns or both.
Obligatory nasty story. In days of old computers used very powerful low voltage power supplies. 5 Volts at 400 Amps for instance. (I have such a power supply.) One story involved a service engineer who forgot to take off his wedding ring. Power supply vaporised the ring. His ring finger dropped to the ground - the wound on the stump nicely cauterised. It was apparently not exactly pain free.
The batteries inside large (many kVA) UPSs are fearsomly dangerous.
Do not under any circumstance make or have a cut that bleeds on both hands then touch them to opposite posts on a 12 volt battery at the same time…
Most of the resistance to current flow is your skin. Blood is better than dirty water in it’s ability to allow current to flow.
One hand, through your body & heart to the other hand = dead idiot.
I have been told that a hot 6 volt car battery is also very dangerous in this kind of circumstance.
YMMV
Dry skin resistance is about 1k to 100k ohms.
Internal resistance, once you get past skin, is about 300 ohms to 1k ohms.
My electronics instructor had a pretty apt saying that he learned in the Navy: “The innards of a human body are a 1/4 watt 470 ohm resistor.” He also told how a dumbass killed himself by pushing the points of the measuring probes of an AC-powered tube ohmmeter through his opposite thumbtips and getting the regulated (but fairly high-current) 12vdc through his body while no one else was around to help him. Maybe a sea story, but maybe not.