Re: [Repeater-Builder] Lightning Protection
Daron, You have done all the right things, so far. Since your antenna is very likely to suffer a direct strike at some point in time, you may want to plan for the worst-case scenario. Heavy-Duty is the name of the game. First and foremost, make certain that the tower itself has the best possible connection to Mother Earth. If one of your antennas is going to take a strike, the stroke current should see a straight, direct, low-impedance path to a good ground. That means that your antenna clamps should have good metal-to-metal contact between the antenna sleeve and the tower member, with some sort of zinc-based contact enhancement compound smeared around the contact areas. If the tower grounding system is not good, the stroke current will take alternate paths through the equipment building- and that means major damage. Next, your equipment cabinet needs to act like a Faraday Cage, so that everything inside is protected from voltage differentials. Your feedline should enter this cabinet through a very robust surge arrestor that is solidly bonded to the cabinet sheet metal. I prefer Huber+Suhner gas tube arrestors, but the best Polyphaser arrestors are okay. The top of the cabinet should be bonded to any overhead trays with #4 copper wire, and the bottom of the cabinet should be bonded to any metal conduits penetrating the slab at floor level, again with #4 copper wire. Do not depend on the equipment grounding conductor bringing 120 VAC to the cabinet, to perform lightning surge grounding duties as well. Of course, the 120 VAC power supply should be protected with a full-wave surge arrestor before it enters the cabinet, and again before the power is distributed within the cabinet. Finally, any telephone autopatch or alarm lines should be fully protected both before and after they enter the cabinet, which entry should be through metal conduit grounded at both ends. Does all of this effort seem excessive? To some people, yes. However, it is grounding and protection techniques like these that have kept my UHF repeater on the air after at least four direct strikes in as many years, when most of the other radios at the same site were seriously damaged or destroyed. Choose wisely 73, Eric Lemmon WB6FLY Daron J. Wilson wrote: Installing VHF and UHF antennas on some towers in locations where the whip may extend above the highest point of the tower, essentially becoming the lightning rod makes me wonder if I'm doing all I can. Currently my plan is a good DC grounded antenna, grounding kit bonding the heliax to the tower just below the antenna and again where it leaves the tower headed into the building. Grounding kit bonded to the grounding bus bar on the exterior of the building where it enters, polyphaser lightning arrestor inside the building grounded to the inside bus bar. Am I missing anything obvious? The polyphaser seems rather small, but they must be able to do the job. Just trying to do all I can to protect the equipment. Thanks in advance Daron J. Wilson, RCDD ) ) Telecom Manager ( ( LH Morris Electric, Inc. ) ) (541) 265-8067 office _|| mmm! (541) 265-7652 fax ( || coffee! (541) 270-5886 cellular \|| [EMAIL PROTECTED]|| Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Lightning Protection
As I recall,they want the polyphaser at the cable entry to the building and grounding kits on the hardline every so many feet.Been a while since I saw a spec sheet. Google search will bring up tons of info... - Original Message - From: Daron J. Wilson [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Thursday, April 08, 2004 12:06 PM Subject: [Repeater-Builder] Lightning Protection Installing VHF and UHF antennas on some towers in locations where the whip may extend above the highest point of the tower, essentially becoming the lightning rod makes me wonder if I'm doing all I can. Currently my plan is a good DC grounded antenna, grounding kit bonding the heliax to the tower just below the antenna and again where it leaves the tower headed into the building. Grounding kit bonded to the grounding bus bar on the exterior of the building where it enters, polyphaser lightning arrestor inside the building grounded to the inside bus bar. Am I missing anything obvious? The polyphaser seems rather small, but they must be able to do the job. Just trying to do all I can to protect the equipment. Thanks in advance Daron J. Wilson, RCDD ) ) Telecom Manager ( ( LH Morris Electric, Inc. ) ) (541) 265-8067 office _|| mmm! (541) 265-7652 fax ( || coffee! (541) 270-5886 cellular \|| [EMAIL PROTECTED]|| Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Lightning Protection
It would be smart to run a awg4 solid/bare copper wire to the top from a wide spread grounding rod array and use this with split bolts along the way for your antenna/s for grounding, the flange or slip joints don't really do well after 5-8 years of oxidation and mechanical coating/paint decay. You can be assured of a good system ground by following NEC article 250, one thing that is tough to understand about the code is the adding of grounding spurs using split bolts to other racks along the way down or up depending on which side you are looking from - the grounding of the service entrance and grid must be exothermic meaning crimps tubes which can not be backed off with wrenches, extension of the grid may be done any way fashionable with 250, meaning fence doorways can be made flexible as desired but the main ground for the load center and the top of the tower must never be allowed any adjustments or changes except for additional conductor taps as needed. Daron J. Wilson wrote: Installing VHF and UHF antennas on some towers in locations where the whip may extend above the highest point of the tower, essentially becoming the lightning rod makes me wonder if I'm doing all I can. Currently my plan is a good DC grounded antenna, grounding kit bonding the heliax to the tower just below the antenna and again where it leaves the tower headed into the building. Grounding kit bonded to the grounding bus bar on the exterior of the building where it enters, polyphaser lightning arrestor inside the building grounded to the inside bus bar. Am I missing anything obvious? The polyphaser seems rather small, but they must be able to do the job. Just trying to do all I can to protect the equipment. Thanks in advance Daron J. Wilson, RCDD ) ) Telecom Manager ( ( LH Morris Electric, Inc. ) ) (541) 265-8067 office _|| mmm! (541) 265-7652 fax ( || coffee! (541) 270-5886 cellular \|| [EMAIL PROTECTED]|| -- 73...Clark Beckman N8PZD Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] Lightning Protection
It would be smart to run a awg4 solid/bare copper wire to the top from a wide spread grounding rod array and use this with split bolts along the way for your antenna/s for grounding, the flange or slip joints don't really do well after 5-8 years of oxidation and mechanical coating/paint decay. You can be assured of a good system ground by following NEC article 250, one thing that is tough to understand about the code is the adding of grounding spurs using split bolts to other racks along the way down or up depending on which side you are looking from - the grounding of the service entrance and grid must be exothermic meaning crimps tubes which can not be backed off with wrenches, extension of the grid may be done any way fashionable with 250, meaning fence doorways can be made flexible as desired but the main ground for the load center and the top of the tower must never be allowed any adjustments or changes except for additional conductor taps as needed. Thanks, that is a good idea. Just to clarify though, exothermic requirements refer to cadweld type connections, the other requirements are 'irreversible crimp' which refer to the sleeve or tube that is crimped and cannot be taken off. Daron J. Wilson, RCDD ) ) Telecom Manager ( ( LH Morris Electric, Inc. ) ) (541) 265-8067 office _|| mmm! (541) 265-7652 fax ( || coffee! (541) 270-5886 cellular \|| [EMAIL PROTECTED]|| Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Lightning Protection
According to PolyPhaser, the best grounding material is copper strap, then solid copper (or copper clad) wire. They don't recommend using stranded wire due to increasing inductance as the strands start to weather and corrode between each conductor. Chuck WB2EDV - Original Message - From: KD5SFA [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Friday, April 09, 2004 9:51 AM Subject: RE: [Repeater-Builder] Lightning Protection Wouldn't a stranded copper wire do better in the event of a strike ? If I recall correctly, lightning has a fairly large AC component and likes to travel on the surface of the wire (Skin effect). Thus by having stranded wire, it could carry a larger current to the ground because you would have more surface area for it to run along. A number of people I know run 2/0 and 4/0 stranded copper from their tower legs to their grounding systems for that reason. 73, Jon KD5SFA Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] Lightning Protection
Chuck is exactly correct. Before I retired I owned multiple towers and we used PolyPhaser and copper strapping at all the sites. I can send you pics of my ham tower (Rohn 55) with the PolyPhaser entrance. It's grounded using 6 copper strap and then 3 strap going to the operating positions. I've got about 12 different coaxes coming in with Polyphasers on them on the entrance panelincluding my Sat dish, TV antenna, repeater, HF, VHF, UHF antennas. Gregg R. Lengling, W9DHI, Retired Administrator http://www.milwaukeehdtv.org K2/100 S#3075 KX1 S# 57 Politics is the art of appearing candid and completely open, while concealing as much as possible. -States: The Bene Gesserit View -Original Message- From: Chuck Kelsey [mailto:[EMAIL PROTECTED] Sent: Friday, April 09, 2004 10:19 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Lightning Protection According to PolyPhaser, the best grounding material is copper strap, then solid copper (or copper clad) wire. They don't recommend using stranded wire due to increasing inductance as the strands start to weather and corrode between each conductor. Chuck WB2EDV - Original Message - From: KD5SFA [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Friday, April 09, 2004 9:51 AM Subject: RE: [Repeater-Builder] Lightning Protection Wouldn't a stranded copper wire do better in the event of a strike ? If I recall correctly, lightning has a fairly large AC component and likes to travel on the surface of the wire (Skin effect). Thus by having stranded wire, it could carry a larger current to the ground because you would have more surface area for it to run along. A number of people I know run 2/0 and 4/0 stranded copper from their tower legs to their grounding systems for that reason. 73, Jon KD5SFA Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Lightning Protection
Exothermic is a connection not soldered, could be crimp tubes or cad welded as used on the tops of the ground rods. It is dangerous to cad weld up in the air - the discharge could start roofing on fire or cause other cables and site personel trouble, I always pack around the holes with thumb gum used as the seal between building penetrations and in/out bound lines, it is available in a number of styles which all have equal integrity but the point I am trying to make is even when the wires are wrapped with something around the mold body the sparks and discharged copper spread wide and hot causing what looks like fireworks show. If you have ever been near a shorted primary feeder and had your skin filled with small copper balls you will know why not to do cadwelding very far above grade, if anything goes astray it burns right thru face sheilds, conventional clothing, needless to say skin, hair and eyes. Daron J. Wilson wrote: It would be smart to run a awg4 solid/bare copper wire to the top from a wide spread grounding rod array and use this with split bolts along the way for your antenna/s for grounding, the flange or slip joints don't really do well after 5-8 years of oxidation and mechanical coating/paint decay. You can be assured of a good system ground by following NEC article 250, one thing that is tough to understand about the code is the adding of grounding spurs using split bolts to other racks along the way down or up depending on which side you are looking from - the grounding of the service entrance and grid must be exothermic meaning crimps tubes which can not be backed off with wrenches, extension of the grid may be done any way fashionable with 250, meaning fence doorways can be made flexible as desired but the main ground for the load center and the top of the tower must never be allowed any adjustments or changes except for additional conductor taps as needed. Thanks, that is a good idea. Just to clarify though, exothermic requirements refer to cadweld type connections, the other requirements are 'irreversible crimp' which refer to the sleeve or tube that is crimped and cannot be taken off. Daron J. Wilson, RCDD ) ) Telecom Manager ( ( LH Morris Electric, Inc. ) ) (541) 265-8067 office _|| mmm! (541) 265-7652 fax ( || coffee! (541) 270-5886 cellular \|| [EMAIL PROTECTED]|| -- 73...Clark Beckman N8PZD Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] Lightning Protection
Exothermic is a connection not soldered, could be crimp tubes or cad welded as used on the tops of the ground rods. It is dangerous to cad weld up in the air - the discharge could start roofing on fire or cause other cables and site personel trouble, I always pack around the holes with thumb gum used as the seal between building penetrations and in/out bound lines, it is available in a number of styles which all have equal integrity but the point I am trying to make is even when the wires are wrapped with something around the mold body the sparks and discharged copper spread wide and hot causing what looks like fireworks show. If you have ever been near a shorted primary feeder and had your skin filled with small copper balls you will know why not to do cadwelding very far above grade, if anything goes astray it burns right thru face sheilds, conventional clothing, needless to say skin, hair and eyes. Can't argue with you about the hazards, I'm quite aware of that. However, Exothermic (by definition) is a process in which heat is given off to the surroundings. Exo- is out side, -thermic is heat. An irreversible crimp sleeve in no way qualifies as Exothermic, though soldering could certainly qualify to the broad definition since heat is given off to the surrounding during the process. Daron J. Wilson, RCDD ) ) Telecom Manager ( ( LH Morris Electric, Inc. ) ) (541) 265-8067 office _|| mmm! (541) 265-7652 fax ( || coffee! (541) 270-5886 cellular \|| [EMAIL PROTECTED]|| Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Lightning Protection
Put Polyphasers on the AC power lines and phone lines? Al N8ARO - Original Message - From: Daron J. Wilson [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Thursday, April 08, 2004 12:06 PM Subject: [Repeater-Builder] Lightning Protection Installing VHF and UHF antennas on some towers in locations where the whip may extend above the highest point of the tower, essentially becoming the lightning rod makes me wonder if I'm doing all I can. Currently my plan is a good DC grounded antenna, grounding kit bonding the heliax to the tower just below the antenna and again where it leaves the tower headed into the building. Grounding kit bonded to the grounding bus bar on the exterior of the building where it enters, polyphaser lightning arrestor inside the building grounded to the inside bus bar. Am I missing anything obvious? The polyphaser seems rather small, but they must be able to do the job. Just trying to do all I can to protect the equipment. Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
