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Author Topic: Shack grounding system  (Read 1119 times)
KEVH53
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Posts: 8




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« on: May 06, 2009, 07:09:40 PM »

Hi, brand new to the site today. I have a question about the feasability of using a 1/2" copper alloy (not pure copper) pipe salvaged from an industrial hot water boiler for a grounding system. If I CAN use this pipe in place of a solid rod, should I include some rock salt when backfilling or driving the pipe for better conductivity? I will of course use the accepted formulas for the number of ground rods used, spacing etc. I have a gravel/clay soil to deal with.
I have been into SWL, but at some point want to become a HAM operator.

Equipment on hand: Drake R8, MFJ Versa Tuner 3 1.5 KW, inverted L end fed, Kaito 1102, Grunding S350.

Location: Rocky Mountain West.
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K9KJM
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« Reply #1 on: May 06, 2009, 10:20:09 PM »

The main reason for a "regular" ground rod being heavy copperclad steel is for mechanical strength so it can be driven deep in the ground.

Depending on your soil type, You may or may not be able to drive your tube very deep. (Standard rods are 8 feet deep)  At about only 10 bucks each brand new at most home supply stores, The nice heavy copperclad 5/8"X 8 foot rod is cheap.

The "best" method installing rods is to drive them in. Either by hand (A fence post driver helps get them started) Or by using a powered "Jackhammer" of some type. You want the firm contact with the soil.
Do NOT listen to anyone who advises they be "washed" in with water. The water method may get them into the ground, But the rod will not have good firm contact with the soil.

Should you have something like close bedrock where nothing can be driven deep, An alternative is to dig a trench and fill with some type of enhancement (Like your rock salt) and backfill. But that is no where near as good as a driven rod, You just have no choice in such a case.

Most all types of copper alloy tubes I have seen will work fine for conductivity.
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KEVH53
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« Reply #2 on: May 07, 2009, 03:11:26 PM »

Thank you for your reply, K9KJM. I had not checked the local hardware store for copper clad rods yet, but I remember the last house I built here in Idaho the code demanded an 8' solid copper rod for the mains, and wow they are pricey! Good to know the recommended ground rods in this case are inexpensive, so I'll just go pick up a few and forget the scrap pipe for now, heheh. I have a wind generator on a 40' mast as well, (at my cabin where my radio equip. is) so I really do have to go the extra mile for lightning protection.
Thanks again..
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K9KJM
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« Reply #3 on: May 07, 2009, 11:36:04 PM »

Don't toss the copper tube in the scrap heap however!

It can be used as a nice low inductance conductor between your rods if nothing else.

Most all codes call for the heavy copperCLAD steel rods, Most home supply stores sell them in 1/2" X 8 feet deep, Or 5/8" diameter X 8 feet deep.  As there is only  a few pennies difference in cost, I usually get the 5/8" rods.
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K1DA
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« Reply #4 on: May 14, 2009, 12:36:15 PM »

   I have been using copper pipe in sandy soil for years. I use water pressure and the sand settles around the pipe quickly -- hard to pull it out after
a couple of weeks.  Copper water pipe comes in different wall thickness and the thickest stuff can be driven with percussion into most soils.  Want more than 8 feet-- solder in a union.  
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WW5AA
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« Reply #5 on: May 15, 2009, 12:12:05 PM »

A better choice for backfill if needed is bentonite (clumping cat litter). It is just as good as rock salt and is non-corrosive.

73 de Lindy
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KEVH53
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« Reply #6 on: May 16, 2009, 04:11:36 PM »

Thank you, WW5AA . Great advice on using bentonite. That reminded me that when my water well was installed a couple years ago the operator told me he had used 'quite a bit' of bentonite to seal the well against ground water contamination. This leads me to another idea... should I include my well casing (60 feet) in my grounding system? I'm thinking it might be one hell of a ground rod. Thanks again, Lindy.

Kevin
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W6EM
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« Reply #7 on: May 16, 2009, 06:41:16 PM »

Kevin:  If the well casing is steel and its galvanized, go for it.  However, many domestic wells these days use pvc.  The argument against it would be running substantial copper wire underground to it to preserve a very low ground resistance path.  If it happens to be the best ground around, a close in lightning strike will find it, and your submersible pump may be part of the discharge path.

The main thing to keep in mind is bonding every ground together.

I've seen plenty of lightning strike locations where the ground rod is ignored and the lightning follows a metal water pipe.  That's why its important to tie everything together.  If the ground resistance is just half an Ohm, lightning currents of 50,000 to 100,000 Amperes can, well, raise things tied to a half Ohm ground to between 25 and 50KV!!

As to the comment against "burying" a ground rod in an augered hole, well, power utilities install ground grids inside substations by laying copper wire in open trenches and then backfilling.  And, like I witnessed above, the trenched and backfilled metal water pipe was a much better ground than was the single 8 foot ground rod.

Oh, almost forgot.  If your local authority insists on a solid copper ground rod, take them to task.  Why? Well, the National Electric Code seems to think an AWG No. 6 copper grounding electrode conductor is all that's needed in many service entrance situations involving residences.  Since UL listed ground rods only have to have a .010 inch thick coating of copper over the underlying steel rod, and the combination of the steel and copper plating has a lower resistance per unit length than does an AWG No. 6 copper conductor, ask them WHY!!!

Good luck.

Lee
W6EM



 
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KEVH53
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« Reply #8 on: May 17, 2009, 04:10:03 PM »

Lee, the case is steel, but not galvanized. The DC submersible pump is also grounded via 6 ga. copper. I will defininatly have everything bonded to ground. The Idaho code I cited is years old. I'm sure that copper clad ground rods are accepted now. Maybe my inspector was invested in copper...  I'll check my current code book just to be sure. I've decided that I will go with the 5/8" copper clad rod that K9KJM had also suggested. I'm still eyeing my well casing and getting nervous about the submersible DC pump (damn! those are expensive!!) but in the last two years it has either sucked up lightning strikes or has escaped them altogether?!

Thanks to everyone that has offered so many great suggestions/comments on this newbie's desire to get grounded! I'm all ears..

Kevin
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K9KJM
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« Reply #9 on: May 17, 2009, 10:10:24 PM »

DO bond to the well case.  (Also make sure your entire electric system is properly bonded and you have a "whole house" surge suppressor in your panel)

(You will want your electric service entrance panel ground also bonded to that well case.)

I have a tower about 6 feet from my well case, And one of the first things I did was bond to the well case.
That tower has taken a number of direct lightning strikes over the years with no problems to the pump.

It is when things are not properly bonded together that stuff gets damaged.

http://members.cox.net/pc-usa/station/ground3.htm

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KEVH53
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« Reply #10 on: May 21, 2009, 04:35:13 PM »

Thanks K9KJM. I would also like to know more about 'the whole house' surge protector. Does anyone have brand name recommendations?

Kevin
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K9KJM
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« Reply #11 on: May 22, 2009, 12:05:30 AM »

One of the best low cost deals I have seen is for a Delta right on Ebay: http://cgi.ebay.com/Delta-Lightning-Arrestor-AC-Surge-Protector-LA302-DC_W0QQitemZ400037330945QQihZ027QQcategoryZ41981QQssPageNameZWD1VQQrdZ1QQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247

35 bucks plus shipping. (Do make sure you are getting the AC version, This company sells both DC and AC)

Many companies sell them, Home supply stores around here sell the Square D whole house protector for close to 100 bucks, General Electric made them a few years ago (I used lots of those in Cable TV systems at each power supply with great results)

ICE sells them for 60 some bucks
http://www.iceradioproducts.com/impulse2.html#6

Polyphaser has them, So do lots of other companies.

They can get more expensive (And more complicated)
Leviton has a slightly better model:
http://www.smarthome.com/4860/Leviton-Whole-House-Surge-Suppressor-Surge-Protector-51120-1/p.aspx

Transtector sells some really good ones that are used at major commercial tower sites, (But they are also quite expensive!)
http://electronic-components.globalspec.com/datasheets/175/TranstectorSystems


I consider a surge protector like the fairly low cost Delta a MUST at any average hams home (Or for that matter, ANY home!)    And I look at those really expensive ones as overkill.   If you have money burning a hole in your pocket fine. Otherwise stick to the lower cost versions.
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KEVH53
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« Reply #12 on: May 24, 2009, 03:38:29 PM »

Thanks for your reply K9KJM. I think I will check out the Delta. I'm glad I asked about the 'whole house surge protector'. I've never really felt like the dept. store version surge protector (a million varieties!) between the recepticle and my vulnerable electronics was sufficient! In this case I believe more IS better! Thanks again.

Kevin

p.s. Just had a HUGE lightning storm here in S.E. Idaho... nice reminder to have the BEST ground system!
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WB2WIK
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« Reply #13 on: May 24, 2009, 07:31:35 PM »

Good insurance is also a great idea.

Most insurance policies cover "acts of God" pretty well, but there can be disclaimers...read them carefully!

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