Date: Tue, 6 Nov 2001 22:16:20 -0800 From: "Ted Mittelstaedt" <tedm@toybox.placo.com> To: "Bill Moran" <wmoran@potentialtech.com>, <questions@FreeBSD.ORG> Subject: RE: Welders causing dial-out to fail Message-ID: <000501c16753$b7bc4500$1401a8c0@tedm.placo.com> In-Reply-To: <3BE81735.7020302@potentialtech.com>
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>-----Original Message----- >From: owner-freebsd-questions@FreeBSD.ORG >[mailto:owner-freebsd-questions@FreeBSD.ORG]On Behalf Of Bill Moran >Sent: Tuesday, November 06, 2001 9:01 AM >To: questions@FreeBSD.ORG >Subject: Welders causing dial-out to fail > >We're searching a few avenues for a solution, one being the >manufacturers of the welding machines, but I thought I'd put the >question out to this list and see if anyone else has worked through >and found a solution for a problem like this. > I would suggest that you look at your grounds first. It really takes a lot of close physical proximity for appreciable interference to be induced through the air onto communications cables. However, if the "ring" side of the phone line has bad coupling to true earth ground, then all hell breaks loose. The National Electric Code mandates that all lines (power, phone, cable, TV, etc) must be grounded together before entering a building. This is usually done with a steel cable that runs down the side of the telephone pole into a stake into the ground. If the ground is dry and the stake is corroded and you get a few milliohms of resistance there, this creates a path for RFI to be coupled directly from the power lines that are operating the welders right into your phone lines. It's the utilities responsibility to correctly ground, call them up and get them out there. All the shielding in the world won't be worth a damn if you don't have a single reference ground for everything in the building. All shielding has to be bonded to this ground to be any good. Ted Mittelstaedt tedm@toybox.placo.com Author of: The FreeBSD Corporate Networker's Guide Book website: http://www.freebsd-corp-net-guide.com >TIA >-- >Bill Moran >Potential Technology >http://www.potentialtech.com > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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