Electronic – Stripping USB Cable – What to do with shielding

usbwiring

I'm new to electronics so please bear with me.

I'm stripping a USB cable that I want to connect to another component – a 5V fan for example.

On the side pictured, i'm connecting up to a 5V fan. And on the other side is a regular USB connector which will plug in to a 5V DC power supply.

After stripping, I have noticed there is a outer wire running along the cable. On the left of the picture:

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From my searching i've found this is a shielding wire. Is this correct?
In the case where i'm not looking to shield and only provide power supply (not even use the data wires) what should I do with this extra wiring of the shield? I have heard that shield should be grounded. So should I:

  1. Combine shield and ground wire
  2. Ground shield wire separately
  3. Leave shield wire floating

Best Answer

Both options 1 and 3 are perfectly acceptable for power-only. If you want less noise on the power supply you should probably go with option 1 - tying the shield pins to the ground pin of the USB port. For signalling as well, 1 is the better option.

For power only, bear in mind you should not try to draw more than 100mA without negotiating with the USB host for more. Be sure to factor that in when deciding if the load can be driven by a USB port.

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