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USB-Based Ground Loops

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  • Answered

Hi, I would like to ask about ground loops. Since you sell this product below in preventing ground loops for ethernet,

Do ground loops also exist in USB cables? For example, you have a printer connected to the computer via USB and that both devices get their power from a 3-prong power cord in each. From my view, it seems they're being double-grounded.

If so, is there a way to prevent these USB-based ground loops the same way as the Shielded Ethernet Ground Loop Isolator? Please let me know. Thanks.

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Satisfaction mark by Eri Turalo 2 years ago

Thank you for the simple answer.

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Shaun A Kranish Principal
  • Answered

If your printer has a 3-prong plug, and it is hooked up to your computer via USB, then chances are you are correct - you would be double-grounded.  You would have a ground loop there.  It's best to test - because we still want everything to be grounded.  Use a multimeter like the one in our Body Voltage Kit and test resistance.

If you do, indeed, have a ground loop (I would recommend testing the USB cord from the computer, and then also the USB port on the printer), here is what to do...Get a 2-to-3 prong outlet adapter.  The kind they make to plug into 2-prong outlets that do not have a ground hole and allow you to plug a 3-prong cord into it.

That will eliminate the ground from one device and eliminate your ground loop.  But only use this product if there is, indeed, a ground loop.  Test and verify first before assuming.  It would be bad to unground your printer cord if its USB port is not grounded to its own cord as well.

ElectraHealth Principal

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