USB negative lead and ground shield - can/should they be linked?

Thread Starter


Joined Oct 10, 2014
It's been awhile since I've taken apart some USB cables but IIRC they often have the negative/black USB lead tied to the ground or cable shield. Since this is the case I'm wondering if it is possible to use 4 conductors for a USB cable. I've tried this and it seems to work but I'm wondering if it is because the device I'm plugging it into doesn't have it's own power source, as it is powered through the USB power. I've never tried this with a device that has it's own power source and thought that it might make a difference.

The reason I ask is I'm trying an experiment using larger gauge twisted pair wire to see if the distance can be increased without an amplifier or repeater. I was able to use a 50ft cable plus ~8-10ft of internal cables/wires (from the motherboard pinout to the keyboard circuit board connector) with no problem at all and the keyboard has a powered hub which seemed to work fine for a wireless mouse receiver and USB thumb drive. I didn't test transfer speeds but there seemed to be no problem with transfer.

My cable only has 4 conductors so I can't include a ground/shield, otherwise I would. I just want to know if I am risking damaging something by trying this.


Joined Jun 22, 2012
The Usb has 4 wires, +/- 5V, data, clk, the Screen is connected to the ground usually Earth or Battery Negative is the same..