I thought we all had a long conversation not too long ago and was determined that Lightning CAN NOT cause E.M.P.
Michael ----- Original Message ----- From: "Nish Park" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Sunday, June 29, 2003 9:45 AM Subject: RE: [smartBridges] Grounding?! > Wow. This are nice tips John. We will make sure to include them in our > product documentation to help others. Thanks. > > Nish > > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of John Hokenson > Sent: Sunday, June 29, 2003 3:01 PM > To: '[EMAIL PROTECTED]' > Subject: Re: [smartBridges] Grounding?! > > I've been involved with designing and installing communications systems > for > over thirty years, are here is my take on the proper installlation and > grounding of the SmartBridge units (and WISP equipment in general).... > > TOWER TOP ACCESS POINTS/BRIDGES > > 1. In any area that is prone to lightning, grounding and protection > of > the antenna port is a must. With the units that are fed from the ground > with PoE (power over ethernet) and an antenna jack, first--screw a high > quality lightning supressor on the N-female jack on the radio--the > Polyphaser PSX-ME is what I prefer. It has a male connector to screw > onto > the radio and a female for attachment of the antenna cable. Since the > case > of the radio is plastic and does not ground to the tower (not really a > good > idea in my opinion but we're stuck with it), use a grounding kit to > securely > bond the body of the protector to the metal leg of the tower. > 2. I am suspecting that many of the radio failures are due to induced > emp > from nearby lightning strikes on the ethernet cable itself which is > acting > as an antenna to pick up the pulse. For this reason I suggest the use > of > outdoor shielded cat5--the kind with icky pick embedded in the inner > layer > among the pairs, a first pvc insulation layer, an aluminum jacket with > additional icky pick and finally an outer PVC jacket. At the radio end, > terminate the connection as close as you can get it to the radio--the > new > style radios I would terminate it in the weatherproof splice box. You > will > need a bonding kit to attach a ground wire to the aluminuum > jacket--these > are commonly made by 3M and available from Graybar. Using a #10 or > larger > wire attached to the stud on the grounding kit, bond the shield to the > leg > of the tower, keeping the ground wire as short as possible. The best > way I > have found to do this is to assemble the grounding kit to the shield > about > 6" from the end of the cable where the pairs will be attached, then > slide > some Panduit DB shrink with hot glue sealant inside over the splice and > shrink it down to weather seal the bond. Since you also need the ground > for > the antenna protector, you can clamp a phospher bronze ground clamp to > the > leg of the tower directly below the radio and attach both the ground > from > the antenna protector and the cat5 ground to the same point. Graybar > has > the Panduit shrink and ground clamps as well. > 3. Install another bonding kit on the cat5 where it leaves the tower, > again you can seal it with Panduit DB shrink. > 4. If the run up the tower is more than 150' (50M) or so, I would > probably bond the shield in the middle of the run as well. > 5. Where the cat5 terminates, again bond the shield to a ground....#8 > or > larger copper wire back to the tower ground is preferable, lacking that > the > building ground....and make sure someone has bonded that to the tower > ground > with #6 or larger copper. > 6. Lastly, between the end of the shielded cat5 and the PoE injector, > install a good quality PoE surge suppressor--Motorola makes a nice one > for > their Canopy products and is available from Tessco for about $40. Make > sure > the ground stud on it is tied to the same ground feeding the end of the > cat5 > shield. > 7. Code generally requires that the protector beinstalled where the > cat5 > enters the building, so the place to terminate the shielded cat5 and > install > the Motorola cat5 protector is on the outside of the wall, and > transition > there to normal cat5 in to your power injector. > > ROOFTOP ACCESS POINTS/BRIDGES > > 1. Many times either an access point or cpe radio will be installed > on > the top of a commercial building or home. The same rules apply with > some > modifications because of the installation. > 2. If it is a customer radio that is not as critical as an access > point, > you may choose to dispense with the lightning supressor on the > antenna--but > DO at the minimum bond the shield of the coax to the galvanized metal > support mast or support structure or DSS mount. One option for this > would > be to loosen the lock nut for the N female connector on the radio and > install a piece of sheet metal under the nut to attach a ground > wire--we've > done this and it works well. > 3. You still need to use shielded cat5 and bond the shield to the > common > antenna ground point as described in the previous section on tower > grounding. > 4. Since the antenna support is most likely not grounded in this > instance, you need to attach a #6 copper wire to the support stucture > (the > 5/16 bolts securing the tripod to the mast is a good spot) and bring it > down > along with the cat 5 to where things enter the building. > 5. Attach the #6 wire to the ground lug on the cat5 protector, along > with > the cat5 shield, then continue to the closest attachment point to the > building system ground. > > INDOOR ACCESS POINTS AND BRIDGES > > 1. In those cases where the installation is using an indoor unit with > coax out to an outdoor antenna, I would direct you to a typical > installation > of a certified SmartBridge CPE: > http://www.vircom.net/pictures/res-install/res-install.htm > 2. In the case of an indoor access point, the only change I would > suggest > is installation of a Polyphaser PSX instead of simply a bulkhead ground > at > the entrance point. > > Hope this helps a few of you out there avoid unnecessary failures. > > ========================================== > John Hokenson, Operations Manager > VIRCOM.NET > reply to: [EMAIL PROTECTED] > 425-558-0674 bellevue > 425-432-8172 king county > 206-341-9421 seattle > 800-806-7446 toll-free > 425-432-8173 fax > WWW.VIRCOM.NET > giving you the world since 1994 > ========================================== > ----- Original Message ----- > From: "David Berndt" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Saturday, June 28, 2003 9:50 PM > Subject: [smartBridges] Grounding?! > > > > A bit of a mid-night rant here. > > > > I've been thinking on a lot of the failures we hear talked about here > on > > the list, the quesitons about lightning, potential lightning strikes, > > lightning striking near by. Alot of the answers seem to be a > combination > of > > finger crossing and some black magic. > > > > So what I'd like to see to rectify some of these issues is smartbridge > > publish a document about proper grounding. Where do we need > grounds/surge > > protectors/lightning arrestors, the differences between them, etc. > > > > I know these things are all dictated by the local building code and > the > > like wherever you happen to be using the product. But how about some > sort > > of a document that is intended as a bare minimum/recommended practices > > document to get all the installs to be put together in a fairly > similar > way > > and help correct some of the new newbie mistakes and take a bit of the > > black magic out of this. > > > > This could be a fairly simple diagram of a few different sample setups > of > > the outdoor equipment. I am especially interested in the total > equipment, > > is there a polyphaser in there? Should the cat5 be grounded when using > > sheilded cat5, otherwise? Surge protector on the cat5? before/after > the > POE > > device? etc etc. > > > > A recommended parts list wouldnt be horrible either. I do not want to > see > > this enforced, but more documentation and standardization would make > things > > clearer for everyone, provide a quick way to answer peoples questions > and > > maybe make everyones systems a bit more stable. > > > > Hope that made some degree of sense. > > > > Dave > > > > The PART-15.ORG smartBridges Discussion List > > To Join: mailto:[EMAIL PROTECTED] (in the body type subscribe > smartBridges <yournickname> > > To Remove: mailto:[EMAIL PROTECTED] (in the body type unsubscribe > smartBridges) > > Archives: http://archives.part-15.org > > The PART-15.ORG smartBridges Discussion List > To Join: mailto:[EMAIL PROTECTED] (in the body type subscribe > smartBridges <yournickname> > To Remove: mailto:[EMAIL PROTECTED] (in the body type unsubscribe > smartBridges) > Archives: http://archives.part-15.org > > > The PART-15.ORG smartBridges Discussion List > To Join: mailto:[EMAIL PROTECTED] (in the body type subscribe smartBridges <yournickname> > To Remove: mailto:[EMAIL PROTECTED] (in the body type unsubscribe smartBridges) > Archives: http://archives.part-15.org > > The PART-15.ORG smartBridges Discussion List To Join: mailto:[EMAIL PROTECTED] (in the body type subscribe smartBridges <yournickname> To Remove: mailto:[EMAIL PROTECTED] (in the body type unsubscribe smartBridges) Archives: http://archives.part-15.org
