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Short-circuit incidents

P

PeeringInside

macrumors newbie
Original poster
Apr 13, 2010
13
2
Hi all,

A few years ago, one end of a lightning cable was plugged in to my MacBook Pro and the other end came into contact with the metal case of a PC laptop. It resulted in a loud pop and a flash, and it blew out the PC, blackened the point of contact, and melted the end of the cable. The Mac was fine.

Last week, one end of a firewire cable was plugged in to an unpowered external hard drive when the other end touched the metal case of a powered hub. Loud pop, flash, and blow-out of the display, keyboard and trackball that were connected to the hub. Charred spot on the hub, but it and a (different) MacBook Pro appeared to be undamaged.

Needless to say, I'm now hyper-careful in handling cables. But I'm wondering what's going on here, and in particular, if there's some underlying electrical issue that needs to be investigated.

Thanks,

David
 
Last edited:
Holy cow!
That generally should not happen. At least I've never seen that happen to either myself or others. Especially a FireWire cable as the contacts are inside the metal sheathing on the connector. Lighting cables I have personally had them plugged into a device on the USB side and then had them resting on metal, on my skin, in my mouth (just because lol) as well as other conductive areas and surfaces and never had an issue.

I don't really know what to suggest but it is odd
 
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It sounds like either a household wiring fault (hot lead shorted to ground contact or hot and common swapped) and/or a faulty AC adapter/charger that doesn't isolate the mains voltage from the secondary low voltage output side. Not USB, Lightning, FireWire, ... should ever have enough voltage to cause a spark. It sounds like something else it presenting the high voltage to the metal cases.
 
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I agree with member "dwig". Having worked in electronic repair for many years, one of the first things we always did was to use an isolation transformer between the AC power outlet and the device we were working on. You need to get your home wiring checked out before something worse happens.
 
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Thanks, dwig and chscag. I'm going to bring in an electrician. Another adventure with a 102-year-old house.

David M: Is the Lightning cable as tasty as it looks?
 
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