Xref: utzoo misc.consumers:4908 misc.consumers.house:2232 sci.electronics:2951 Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!decwrl!labrea!glacier!jbn From: jbn@glacier.STANFORD.EDU (John B. Nagle) Newsgroups: misc.consumers,misc.consumers.house,sci.electronics Subject: Re: the truth about GFCI's Keywords: GFCI, RFI, noise Message-ID: <17444@glacier.STANFORD.EDU> Date: 12 May 88 16:00:56 GMT References: <2005@hou2d.UUCP> Reply-To: jbn@glacier.UUCP (John B. Nagle) Distribution: na Organization: Stanford University Lines: 19 We've now established that one cannot entirely rely on the protective ground pin as a path to ground. The GFCI handles the safety aspect, but what about the use of protective ground as part of shielding in electronic equipment? Open grounds can cause hum, noise, and weak reception of RF signals. They also can eliminate one of the defenses of electronic equipment vulnerable to static charges. When you walk across the carpet and build up a big static charge, then touch your computer, where does the charge go? Ungrounded GFCIs are rare, fortunately. But it is worth thinking about this if, say, you had a GFCI outlet installed in a house with older wiring because you needed a 3-prong outlet for a computer. It is probably not a good thing to plug elaborate electronics with interconnects to other units, such as computers and sound systems, into such an outlet. On many such units, logic ground is tied to protective ground and the cabinet, so an ungrounded outlet results in a direct connection from the case and cables to the system's ground reference. John Nagle