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Author Topic: Ground bonding options  (Read 5133 times)
NC5T
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Posts: 39




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« on: October 11, 2011, 11:20:46 AM »

Hello,

  I am looking at moving my shack but I have, what might be, a serious issue with the new location and I am looking for some advice.

  The new location is on the opposite side of the house from where I am now which will cut down my feedline runs by about 115 ft and will be much quieter and out of the way than the setup I have now.

  The issue I can't seem to work out is ground bonding for safety/lightning protection.  I have a window pass through entrance panel for my feedlines I have connected to the ground rod right below the window which ties into the mains entrance about 10ft away.  Works great and everything as it should be.

  The problem with the new location I would have to run 200+ feet of wire, and a bunch of ground rods, to make it to the mains entrance as I need to go around the back patio and pool to get to it. This would also put the ground bonding loop out in the yard 50ft or so away from the house so I am not sure how effective it would be.

  The other possible option I have come up with, and my main question, is about using the water lines for bonding two separate ground systems together. I have an outside spigot that will be 3 ft away from the entrance panel ground rods, and another one 5 ft away from the mains entrance. Would it be possible/ safe to connect the ground rods to the pipe at each end and use that to bond the ground rods together? I have done a lot of research on grounding and lightning protection and other than making sure water pipes are bonded into the overall system, I could not find anything on using them for the bonding connection.

  The plan would be 4 ground rods, one every 16 feet, bonded together with #6 wire from the antenna mast to the shack entrance panel, #6 wire running 3ft from the last ground rod to the spigot and then a another ground rod between the spigot and the mains.   I have checked and there is continuity between the two spigots so that would not be an issue.  This would put ground rods on each side of the house bonded together by the copper water pipes in the slab with a lot shorter run than going around the patio/pool.

  There was another similar thread on here about using water pipes, but the issues seemed to revolve around using the pipes as the ground, not using them to bond separate ground systems together.
 

  Thanks in advance for any assistance or any other options anyone could think of.

73,

Bob
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WX7G
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Posts: 6327




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« Reply #1 on: October 11, 2011, 11:23:56 AM »

If you expect a direct lightning strike the coaxial cables should be routed to the AC power ground first and then to the shack. This keeps lightning charge from flowing in the house AC wiring.

It looks like your new shack location makes this difficult to do.
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K9KJM
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« Reply #2 on: October 11, 2011, 10:42:45 PM »

All ground systems need to go to their own ground rod(s) first, THEN be bonded with the other grounds.
It is fine to use your plumbing as a ground conductor only IF it is copper, AND you have visually inspected it along it's entire length  to make sure there are no non conductor parts in the system. I would NOT rely on a simple ohmeter test. There could be things that are poor conductors in the direct path, Yet you could get a low resistance reading with a meter.

Soft drawn copper tube in a roll can be a low cost effective bonding conductor IF you are careful to not kink it. Available at discount home supply type stores at low cost.   1/4 or 3/8" works well.
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NC5T
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« Reply #3 on: October 13, 2011, 07:39:23 AM »

Gentlemen,

Thanks for the replies.  With the steel mast for the dipoles and verticals being the highest points on my property, I am definitely concerned with the lightning threat.

  I think I am going to keep the shack where it is or maybe give remote operations from the other room a try. 

73,

Bob
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K1CJS
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« Reply #4 on: October 13, 2011, 01:41:44 PM »

If you install a good grounding system for your station, you need not be worried about the excess cable run to bond the station ground and the electrical service ground together.  The one purpose for the bonding of the two grounds is to eliminate the possibility of current flowing through your station equipment into your house electrical ground, possibly damaging your equipment--and possibly hurting or killing anyone who may be using your station.

If you have a good station ground system and a good electrical mains ground, a simple run of number six cable between the two will suffice--no further ground rods needed.
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W6RMK
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« Reply #5 on: October 13, 2011, 04:50:11 PM »

and you can run that AWG6 right along the base of the wall, so maybe you don't have to go out and around? I've done stuff like put it on top of the expansion joint between slab and wall. Nothing says the bonding conductor has to be outside, if you're doing it for NEC bonding (as opposed to lightning protection). You can run up and over, for instance (imagine if you're on the third floor of a building..)

If you're looking at lightning grounds, then bear in mind that the majority of the lightning current is hopefully going into the ground at the base of whatever got struck by lightning.  A bonding wire that is 10s of meters long is going have a huge inductance, (200 ft is something like 60-70 microhenries... at 1 MHz that's hundreds of ohms impedance, and hopefully, even a lame ground rod will be lower than that by an order of magnitude)
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W6WRT
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« Reply #6 on: October 17, 2011, 01:30:25 AM »

Remember one basic thing about lightning: Lightning does not want to go into your shack and destroy your equipment. Lightning really just wants to go to ground. Your job is twofold: Give it a short, easy path from your antenna and tower to ground and at the same time  make sure there is NO path into your shack. 

There is only one absolutely guaranteed way to protect your equipment from lightning strikes and that is to completely disconnect all your cables when lightning is near. And don't just unplug them and leave the plugs a few inches apart. The lightning has already traveled a few thousand feet and a couple more inches is nothing. Unplug the cables and move them far, far apart. Don't waste your money on lightning arresters and such stuff. Distance is your friend.

I know it's a nuisance but lightning is nothing to mess with. Do it right.

73, Bill W6WRT
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AA4PB
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« Reply #7 on: October 17, 2011, 05:58:58 AM »

Yes, having your antenna/control cables disconnected and left far out in the yard away from the house is a good bet. The problem is that lightning strikes can precede an actual storm by some distance. Can you absolutely guarantee that you will NEVER have any cables connected during a lightning event?

A proper single point grounding system can protect your equipment at all times. That requires that all antenna cables, control cables, phone cables, TV cables - any copper that leaves the house - exits at ground level near the power entrance. That is often next to impossible (or very expensive) to accomplish on an existing home so we usually end up with compromises.

By the way, the #6 conductor bonding required by the NEC is not for lightning protection. It is to ensure that all ground points are at the same potential for personnel safety reasons. A 200-foot run of #6 around the house works fine for the NEC requirements but can look like a big inductor to a lightning strike.
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BOOTYMONSTER
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« Reply #8 on: October 17, 2011, 09:00:29 PM »

referring back to the OP .....
if the water pipe is connected to the antenna systems ground and lightning strikes the antenna ..... since water is conductive wouldn't that be a huge hazard to anyone in the house taking a shower or washing their hand/dishes or even taking a leak ? wouldn't it also be another connection point to possibly fail ?

http://www.iceradioproducts.com/32.htm
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K9KJM
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« Reply #9 on: October 17, 2011, 10:13:55 PM »

referring back to the OP .....
if the water pipe is connected to the antenna systems ground and lightning strikes the antenna ..... since water is conductive wouldn't that be a huge hazard to anyone in the house taking a shower or washing their hand/dishes or even taking a leak ? wouldn't it also be another connection point to possibly fail ?

http://www.iceradioproducts.com/32.htm

No, Fresh water is NOT conductive.    Anyhow, All portions of the ground system need to go to decent grounds FIRST (Ground rod(s)  Before they are bonded together, And it is a UL lightning protection standard to bond to all metal bodies within 6 feet of other grounds, Since the direct lightning strike will arc over to them anyhow.

All of the metalic plumbing pipes in my home are bonded with the grounding system, And my towers take direct lightning strikes most every storm. 

It is when ground systems are not bonded together that bad things happen........   And you sure want your plumbing system grounded.
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K1CJS
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« Reply #10 on: October 18, 2011, 01:33:23 PM »

Removed by the writer--after a flash of insight!   Roll Eyes
« Last Edit: October 22, 2011, 02:44:21 PM by K1CJS » Logged
W5LZ
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Posts: 477




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« Reply #11 on: October 27, 2011, 01:53:16 AM »

FWIW
Water is a variable conductor depending on what's dissolved (or suspended) in that water.  Distilled water doesn't conduct, but a typical water system is far from being distilled.  It's a very good idea to NOT count on water being an insulator.  It depends on the amount of voltage/current applied too.  It's a pretty safe bet that lightning will supply more than enough voltage/current to make almost anything arc, right?  A properly installed and grounded -metal- water system is safe, and so is a properly installed -plastic- water system.  Neither are a "sure fire" bet for 'grounding'.  Oh well...
 - 'Doc
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K1CJS
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« Reply #12 on: November 08, 2011, 12:31:14 PM »

The only reason that water supply systems aren't required to be grounded today is that today, most construction is using plastic (pvc) water piping.  The requirement of having all metallic water supply systems grounded hasn't been taken off the books--as a matter of fact, it is just as important today as it used to be.
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