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I have an old power supply that I am going to use to power some fans. Does the power cord that connects to the power supply need to be grounded? I have an extension cable with no ground and I'm wondering if it is safe to plug a power supply into it.

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migrated from Oct 12 '10 at 17:32

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up vote 6 down vote accepted

While it will likely be fine (I've run many computers in old houses that had no grounding), it's not advised. A static charge will build up, and depending on where it discharges may cause damage to the electronics.

Annoyingly this damage is usually hard to pinpoint, because it can show itself after a while or lead to only intermittent failure. Not fun to troubleshoot, so if possible put a ground lead on a heating-pipe or other grounded object in your house.

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Does it work; yes. If your in North America, the power system is ground/neutral and a single hot wire (for 120v). That said it's "less safe" without that ground pin explicitly grounding the case to earth ground. I wouldn't do it and I would recommend you do the same.

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It is of course better/safer to have it grounded, but not really necessary. All my power outlets are without a "ground-pin" (except one in the kitchen and one in the bathroom) and I have had (2-4) computers connected without issue for about 12 years.

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The earth is used as part of the safety barrier between input and output. If you operate a power supply that is intended to be earthed without it's earth connection then you can no longer rely on that safety barrier.

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