Toddler burned by USB cable

Longmont Times-Call ^ | 1/9/2010 | Scott Rochat

[KarlInOhio]

I’m fairly sure that if this sort of damage was done the power supply failed... My phone is connected via a micro usb charger which is plugged right into the wall.

Yes, the output should only be a few volts on the USB connector end, but if the converter failed for some reason, it certainly could deliver far more.

Even if the plug is USB shapped, it is quite possible that the power supply didn't limit current like USB is supposed to. It might have just been a step down transformer, a diode rectifier and a 5 volt regulator without any communications to start at a low power 100mA max and step up to 500 mA when requested. It might have been able to deliver a few amps at 5 volts.

Even if you don't have any rug rats running around chewing on wires, it probably isn't a good idea to leave them plugged in with the device side floppy around the floor under the desk because they connectors could short out (as I look down on the floor with two chargers breaking that rule).

[SouthTexas]

Agreed.

[Erasmus]

If it’s 12 volts, then there’s a defect in the power supply. A proper USB delivers only 5 volts, and is limited to half an amp. That’s 2.5 watts.

I’d like to know if there is any reputable medical record of this level of injury occurring with 5 volts inside the mouth. Anywhere, ever.

As to having stuck one end of the cable into an AC outlet, it may be possible to stick the shell of new micro-B style connector into one of recepticle slots, but I don’t see it happening with any of the traditional types.

Just the same, I can imagine the following set of circumstances:

1. A failure of line isolation of the host device power supply that makes the entire cable, including the shield, hot with respect to earth ground, or

1a. The baby manages to stick a micro-B connector into the live prong slot of an AC outlet;

2. The baby is grounded, such as in a tub of water;

3. The baby sticks the cable in its mouth, thus receiving not 5 volts DC but 120 volts AC.

I just don’t see this as a case of 5 volts doing that damage.

[stuartcr]

OK

[Erasmus]

One further point, upon checking the article:

The baby’s heart stopping is suggestive of several milliamperes flowing through the heart. This effect could not be caused by a potential difference of 5 volts confined to the mouth.

I doubt that even 120 volts confined to the mouth would cause this level of current through the heart, although there may be side effects of currents induced entirely within the mouth from 120 VAC that could stop, or fibrillate, the heart.

This further suggests the scenario from my previous post:
120 VAC, and body grounded at or below the chest.

[foolishboi]

Ok, I’m thinking maybe she put the AC cord in her mouth. The 110 line that goes into the dc converter portion sometimes is in the form of a plug, at least on older laptops. Straight USB...no way

[papasmurf]

I agree 100%. IMO, the parents are lying and covering up their own irresponsible actions. Perhaps, even, criminal actions. You’d think hospital staff, Doctors especially, would have recognised this.

Praying for a full physical and emotional recovery for her.

[PA Engineer]

2.625 Watts will NOT do this kind of damage.

I'm with you on this. They are covering up something else. This is a current limiting device unlike say a 9Volt battery. We have all done the tongue test on a battery without this extensive damage.

There are aproximately 9 BTUs max of heat from a standard USB device. The infant's injuries are not consistent with this.

At a minimum it sounds like a wall outlet power chord, but the parents are planning on cashing in by misdirection.

[PA Engineer]

The baby’s heart stopping is suggestive of several milliamperes flowing through the heart. This effect could not be caused by a potential difference of 5 volts confined to the mouth.

Good point. There is much more to this story. Sadly, the police need to step in and investigate to confirm the baby is safe and not going to suffer "intentional" abuse versus the "accidental" alleged in the story.

[Erasmus]

The laptop maker or whomever else gets sued by the parents will hire good lawyers and a good electrical engineering expert witness or two.

They'll tear the story to shreds in conference with the plaintiff's shysters, or in open court if absolutely necessary.

Unfortunately, in a trial judged by their "peers" (whom the plaintiff's lawyers have carefully culled through voir dire) it would be a real crap shoot.

[mazda77]

In some racing data acquisition systems 12VDC is used because of the raw source available without adding additonal power circuits and also elimiating the need for drawing power from the PC on 30 foot plus download cable lengths. Just was making teh point of the absolute maximum voltage I have ever seen in a USB transmission system but you are correct in the 5v line voltage for sourced power supplied from the PC to the remote device.

[Erasmus]

These DAQ systems put 12 VDC on a standard 4-conductor 4-pin USB cable? I’ll have to watch out for that.