I was using a powered USB hub to power a USB external hard drive because the Pi cannot output enough power to power the HD itself.

I plugged the HD into the Pi and it looked like it was working, but I also plugged in the micro USB port too because the hubs power was being distributed to the HD and the pi. But by plugging in both I think I short circuited the Pi. And now it just shows the red light no matter how many times I reinstall the OS onto the SD card. My conclusion? I short circuited it.

What would be the correct configuration to using an external HD the Pi itself cannot power? (Without creating a short circuit.) I used a power usb hub that was recommended for the Pi.

  • Have you tried disconnecting the hard drive and booting the Pi from a dedicated power supply - not a powered USB hub. A USB hub may not deliver sufficient current to reliably power the Pi. Sep 17, 2015 at 22:02
  • Yeah. Still only a red light.
    – X0r0N
    Sep 17, 2015 at 22:02
  • Is there anything still connected to the GPIO pins or via USB? Sep 17, 2015 at 22:03
  • Do you have a multi-meter handy? Some measurements with that would give some indication as to where the Pi broke
    – Darth Vader
    Dec 17, 2015 at 8:10

3 Answers 3


You likely blew the polyfuse. But, pins GPIO pins +5V and ground (2 and 6) could be used to power Raspberry Pi as well. That pin is connected after polyfuse, so if you power it this way you may well bypass your blown polyfuse.


Be aware, this will cicrumvent protection that polyfuse gives. But, I think you could at least test if your RasPi is still functional and this is really polyfuse. And don't try to power it from same hub you connected to RasPi USB ports. Yes, you will have two plugs, which is better than broken RasPi.


Its reasonably likely that you blew the fuse. The Raspberry Pi has a polyfuse, which will "blow" if you draw too much power from the Pi. A quirk of polyfuses is that they can take a long time to reset.

Set your Pi aside, and try using it again in a few hours, or tomorrow even.

Google "Raspberry Pi polyfuse" for more info.

  • Possibly an issue in some case but it broke a few days ago and still only getting a red light.
    – X0r0N
    Sep 17, 2015 at 22:03

My personal recommendation is to always power the Pi using an official Raspberry Pi power supply. Yes you can power the Pi using USB ports on computers and USB phone chargers, but your asking for trouble.

In your case you connected the Pi to a powered USB hub, and also an external HD. Yes I suppose that setup should work in theory. However it really is not a good one. When the product description said the USB hub was recommended for the Raspberry Pi, they did not mean it was recommended for powering it.

The answer to your problem is if you really have killed your Pi, well its not the end of the world, we've all done it at some point. If you do get a new one be sure to use an official Raspberry Pi power supply.

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