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I have a USB cable that I plug my iPhone into while I'm at my desk. Often when I reach to plug it in, there is a small electric shock (especially during winter).

Will this damage anything? I know that electrical equipment can be damaged by small electric discharges. Are USB ports grounded or anything that would protect them?

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up vote 2 down vote accepted

Yes, USB cables are grounded, provided your computer itself is grounded. The external shield for the connection pins is required to connect to the ground wire that runs through the cable. (Source: USB 2.0 Specification)

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It sounds like you are experiencing a discharge of static electricity built up by walking on the carpet etc.

The short answer is that unprotected electronic equipment can be damaged or distroyed by static electricity. That is why when you buy memory or other chips they are in special static safe packages and require special handling during installation.

Most all of the top quality devices and most average devices will include ESD protection on the USB and other connectors to protect against static.

Cheap imported electronics like USB hubs for $5 probably don't include such protection so it is always a good idea to be careful.

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