Members Deeprig9 Posted April 1, 2009 Members Share Posted April 1, 2009 This should be in classifieds perhaps, but it's such a random specific thing. If any of you have some spare bonding/grounding rack screws I would love to buy some from you, I need at least 4 and 16 at the most. All morning I can only find packs of 100 and they are very expensive through Panduit. I even called up my old buddy in South Carolina who is in the fastener business and he can't help me either. I have a paypal account I can pay you with. Certainly one of you purchased a pack of a hundred and have 80 of them laying around in a drawer next to a pack of rubber bands and an incomplete deck of cards. Please let me buy them off you. Thanks! Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted April 1, 2009 Author Members Share Posted April 1, 2009 By the way, this is related to recording because these screws bond the rack equipment to the rack, and with a grounded rack, your equipment is theoretically safe from surges and lightning, also grounds shielded panels, which is my purpose, that eliminates noise and EMI... Link to comment Share on other sites More sharing options...
Members IsildursBane Posted April 1, 2009 Members Share Posted April 1, 2009 By the way, this is related to recording because these screws bond the rack equipment to the rack, and with a grounded rack, your equipment is theoretically safe from surges and lightning No... no.... no, it is not. Ground connections are supposed to provide a safe path for faulty equipment to discharge to the earth. By "safe" I mean not through you. Surges can still cook equipment and lightning will go wherever the hell it pleases. It passed through 1-2 miles of highly resistive air before it hit your gear; nothing in your rack is beefy enough to protect you or the other sensitive bits. -Dan. Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted April 1, 2009 Author Members Share Posted April 1, 2009 No... no.... no, it is not. Ground connections are supposed to provide a safe path for faulty equipment to discharge to the earth. By "safe" I mean not through you. Surges can still cook equipment and lightning will go wherever the hell it pleases. It passed through 1-2 miles of highly resistive air before it hit your gear; nothing in your rack is beefy enough to protect you or the other sensitive bits.-Dan. That's why I used the word "theoretically"... "Theoretically" electricity takes the path of least resistance. Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted April 1, 2009 Author Members Share Posted April 1, 2009 No... no.... no, it is not. Ground connections are supposed to provide a safe path for faulty equipment to discharge to the earth. By "safe" I mean not through you. Surges can still cook equipment and lightning will go wherever the hell it pleases. It passed through 1-2 miles of highly resistive air before it hit your gear; nothing in your rack is beefy enough to protect you or the other sensitive bits.-Dan. You sound pretty knowledgable, let me ask you a question. This rack I'm bonding to the ground is for a shielded patch panel, specifically to drain interference from the 120 cables. The ground wire I'm tapping onto (installed by someone else) goes up and bonds to the ceiling joist in the ceiling, not an earth rod. What risk exists that when lightning strikes this building, it's going to earth itself into my equipment>? Link to comment Share on other sites More sharing options...
Members MrJoshua Posted April 1, 2009 Members Share Posted April 1, 2009 Article 250 of the NEC covers grounding. Article 640 covers specific requirements for audio equipment. Reading through it would be a good idea. Practically speaking, though, I'd try to find a different ground wire - one that you know has a good connection to ground and preferably one that doesn't look like it's intended to be a direct path in case of lightning strike. Although if this is a wooden ceiling joist, which I'm assuming it is, I have no idea what they'd be trying to accomplish by attaching a ground wire to it anyway. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted April 1, 2009 Members Share Posted April 1, 2009 The ground wire on AC outlets and the metal box around it are supposed to go to an earth rod. I say supposed because wires in the box use screw on wire lugs to connect them which over time can corrode and cause poor connections. There may be some resistance involved with the distance the wire travels through the building. If this is a case of lightening protection, buildings that may get struck usually have lightening rods but these are in no way connected to any electronic devices and are completely independant. If a ground is needed because of faulty wiring you can install your own two ways. One would be either drive your own rod and run a wire or connect a ground to a copper water pipe that will go directly to ground. In your case it sounds like you're trying to ground patchbays for stray EMF, Patchbay casings are often built with a floating ground and can hum if they arent properly grounded. If theres equipment involved recieveing AC current then obviously a proper AC filter or isolation transformer may be the best solution. If they are patchbays an independant ground for them is a must and connecting a wire to a cieling joice sounds like some idiot was on drugs. Maybe he was trying to recieve radio stations? Link to comment Share on other sites More sharing options...
Members IsildursBane Posted April 1, 2009 Members Share Posted April 1, 2009 That's why I used the word "theoretically"... "Theoretically" electricity takes the path of least resistance. Actually, if you look at something as simple as Ohm's Law for a parallel circuit, it implies that electricity follows every path, with the amount of current through that path inversely proportional to its resistance. In the majority of electrical circuits, the resistance of the air between conductors is so great as to make the amount of current inconsequential. And "in theory" the lightning is trying to go to the ground - "in theory" having it electrically grounded should make it more susceptible to lightning strikes. It's a lot more complicated when you're dealing w/ extremely high voltages, static buildups on uneven surfaces, and a variety of other things, but don't ever assume that having your gear grounded or ungrounded (or wearing rubber-soled shoes) is going to save you from a lightning strike. -Dan. Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted April 1, 2009 Author Members Share Posted April 1, 2009 I have a low voltage license. And I'm on Harmony Central looking for grounding advice. Is that scary? Nay... it's a testament to the amazing base of knowledge contained herein. Link to comment Share on other sites More sharing options...
Members grantlack Posted April 1, 2009 Members Share Posted April 1, 2009 The ground wire on AC outlets and the metal box around it are supposed to go to an earth rod. I say supposed because wires in the box use screw on wire lugs to connect them which over time can corrode and cause poor connections. There may be some resistance involved with the distance the wire travels through the building.If this is a case of lightening protection, buildings that may get struck usually have lightening rods but these are in no way connected to any electronic devices and are completely independant. If a ground is needed because of faulty wiring you can install your own two ways. One would be either drive your own rod and run a wire or connect a ground to a copper water pipe that will go directly to ground. In your case it sounds like you're trying to ground patchbays for stray EMF, Patchbay casings are often built with a floating ground and can hum if they arent properly grounded. If theres equipment involved recieveing AC current then obviously a proper AC filter or isolation transformer may be the best solution. If they are patchbays an independant ground for them is a must and connecting a wire to a cieling joice sounds like some idiot was on drugs. Maybe he was trying to recieve radio stations? bolded the vitals, this about does it in my estimation. as far as the current... no pun intended... setup, i'm assuming (hoping) by ceiling joist you mean either a) you have metal joists or b) referring to a metal support beam. whoever did it might be able to get away with the logic of steel i-beam-> steel supporting pole-> maybe passing into ground through foundation if that's indeed the case. bad idea either way as the conductivity is going to be poor compared to copper piping. if you actually mean wood ceiling joists... well wood is an insulator. nuff said. Link to comment Share on other sites More sharing options...
Members MrJoshua Posted April 1, 2009 Members Share Posted April 1, 2009 bolded the vitals, this about does it in my estimation.as far as the current... no pun intended... setup, i'm assuming (hoping) by ceiling joist you mean either a) you have metal joists or b) referring to a metal support beam. whoever did it might be able to get away with the logic of steel i-beam-> steel supporting pole-> maybe passing into ground through foundation if that's indeed the case. bad idea either way as the conductivity is going to be poor compared to copper piping. if you actually mean wood ceiling joists... well wood is an insulator. nuff said. If it's actually a steel-framed building, the frame should be properly grounded anyway. If that's the case, using the frame to ground other equipment would be fine. It takes an awfully long run of steel I-beams to develop any noticeable resistance as far as grounding is concerned. Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted April 1, 2009 Author Members Share Posted April 1, 2009 If it's actually a steel-framed building, the frame should be properly grounded anyway. If that's the case, using the frame to ground other equipment would be fine. It takes an awfully long run of steel I-beams to develop any noticeable resistance as far as grounding is concerned. Yes, it's steel. Link to comment Share on other sites More sharing options...
Members Deeprig9 Posted April 1, 2009 Author Members Share Posted April 1, 2009 And the 2008 NEC is in the trunk of my car which is at AAMCO right now being repaired. And I've found that the NEC book falls short compared to Bicsi in it's literature to help people looking for answers in the application of electrical principles in method and practice. Link to comment Share on other sites More sharing options...
Members sharnrock Posted April 1, 2009 Members Share Posted April 1, 2009 The NEC is not designed to help you wire stuff. It is just a book of rules. And that bitch is confusing. Are you talking about the green anodized 10-32 screws? You can pick those up at home depot for a few bucks. To be honest they don't even have to be green, as long as their sole function is to ground the equipment. Link to comment Share on other sites More sharing options...
Members sharnrock Posted April 1, 2009 Members Share Posted April 1, 2009 also, your rack is metal, your rack gear is metal, and it's being supported by 4 10-32s. I'd say it's grounded plenty as long as it's plugged in. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted April 1, 2009 Members Share Posted April 1, 2009 Steel building you're OK. Home depots fine. Just take along what you got and find a close match. Link to comment Share on other sites More sharing options...
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