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Author Topic: 18 Gauge Copper Wire Good for Grounding?  (Read 18438 times)
LA9XNA
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Posts: 107




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« Reply #30 on: August 20, 2014, 04:41:35 AM »

I would recommend you to use the braid from a RG213 or RG214 (slightly thicker)  as a bounding strap form your radio gear to a ground bar.
Use 16 srq-mm lugs(Gauge 5). Borrow or buy a crimptool for the lugs.
They go for as low as 22$ on Ebay.
http://www.ebay.com/itm/0-5-16-mm2-Crimper-for-Insulated-Terminals-lugs-Crimp-Pliers-Crimping-Tool-/360750712270?pt=AU_Hand_Tools&hash=item53fe6b05ce

To protect your equipment from a direct lightning strike is almost impossible because of the high current from the lighting strike.
If you want to protect form low frequency charges it is enough to tie your ground bar into the house earth system (preferably tie into the building main grounding point with a heavy gauge wire). Use Miltie stranded wire similar to auto cable.

If the grounding is to help on RFI and be a Reground you will have to make an under ground grid in your yard.
To obtain the lowest resistance on your earthing system the simplest way is to install one or several main feeders with branches have about 1m (3 ft) between the branches.
The grounding wire have to be covered with 1-3 ft of earth to ensure that the wire is kept moist at all times. To get a very low resistance it is possible to put a hygroscopic material on top of the wire. Bentolit (cat-sand) is a good hygroscopic material.

The underground connections should  be crimp or weld not clamp connections (split bolt) because of corrosion. Use silicone sealant or similar to corrosion protect the joints.

Stay away from copper-weld grounding it is cheep but will not last.

PS!
There is a lit of information about grounding systems on the internet.
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K5TED
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Posts: 728




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« Reply #31 on: August 20, 2014, 03:28:22 PM »

18 ga is definitely too small http://k5ted.net/slide_show.html?picture=picture1.jpg&show=Earthing
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KD0SFY
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Posts: 298




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« Reply #32 on: August 20, 2014, 04:18:21 PM »

 Roll Eyes

The ground from the radio to the grounding buss bar should be standard stranded copper wire at least the same gauge as the power wire.  The wire from the bar to the grounding rod should be at least 6 AWG. 

Just use regular stranded wire.  It is less expensive and a heck of a lot easier than stripping the shield out of RG213/214.  And it doesn't have the common pitfalls associated with braid, nor do you need the extra flexibility of braid. 

If you are putting in a ground for lightning suppression, ideally that should occur outside the house.  Regardless, you need to bond the shield of the coax to ground at the entrance to the building.  There are several ways to do this: 1) use a grounded bulkhead and bulkhead feed thru connector, 2)  use a grounded lightning suppressor, 3) remove the outer insulation from the coax and use a special strap. 

Building a grid under your yard does nothing for RFI. 

If you do put in supplemental grounding rods, they need to be 8 ft long and 5/8ths of an inch in diameter.  They should be spaced at least twice the driven depth from other ground rods, so for rods driving til the head is just above the dirt, they should be at least 16 ft apart, though code allows them to be a minimum of 6 ft apart if more separation is not possible.  They should be interconnected with at least 6 AWG stranded wire.  People usually use uninsulated wire for this and bury it, but you can use insulated wire or even above ground wiring if soil conditions warrant, and it is NOT NECESSARY to keep the ground around the wire moist.

If the connection is to be below ground, use an inspection well if possible.  Do NOT use silicone or RTV sealant on joints.  The chemicals released in the curing process can corrode the metal.  Use the appropriate "Penetrox" in the joint and if desired, coat with a non-conductive grease (aka battery grease). 

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KT4WO
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Posts: 150


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« Reply #33 on: August 27, 2014, 08:24:59 AM »

re:"I told you previously that inspectors would fail any ground connection that is purely soldered -- "

As a former electrical inspector....your right....I would also fail it if it was stranded wire.
(to the ground rod..that is----on single fam. homes)

When you get into com/indust installs...lots of stuff changes(hell of alot bigger wire!!)


Motorola has a great paper/book on grounding TX sites....use this and
you can "sometimes" take a direct hit.

I inspected a cell site ....now you wana talk about copper in the ground!!!...
They do it right.....lol

KT4WO


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KD0SFY
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Posts: 298




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« Reply #34 on: August 27, 2014, 12:02:16 PM »

re:"I told you previously that inspectors would fail any ground connection that is purely soldered -- "

As a former electrical inspector....your right....I would also fail it if it was stranded wire.
(to the ground rod..that is----on single fam. homes)


I am unaware of any requirement in the NEC to use solid wire for the grounding electrode conductor.

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KT4WO
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Posts: 150


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« Reply #35 on: August 27, 2014, 02:04:29 PM »

I reviewed my post as I didn't recall saying it was in the NEC...because it's not.

But I would still "fail" it....Just as I would if the smoke det's were not on a bedroom
branch.(or any branch that you can't live without)(so when the battery died they just didn't kill the power on them)
If u take issue with that...join the local VFD and go into granny and paws house to recover
the bodys after the fire only to find the smokes had been turned off....I HAVE.


I know, I know....I'm sure you would have fought me on it....but are you really
gona hold up your house for weeks to fight that?Huh....99.9% won't. And it WOULD have held it up while
you appeal to the state.


The NEC is a good start....but remember....it's a minimum.

KT4WO



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KD0SFY
Member

Posts: 298




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« Reply #36 on: August 27, 2014, 02:16:05 PM »

I reviewed my post as I didn't recall saying it was in the NEC...because it's not.

But I would still "fail" it....Just as I would if the smoke det's were not on a bedroom
branch.(or any branch that you can't live without)(so when the battery died they just didn't kill the power on them)
If u take issue with that...join the local VFD and go into granny and paws house to recover
the bodys after the fire only to find the smokes had been turned off....I HAVE.


I know, I know....I'm sure you would have fought me on it....but are you really
gona hold up your house for weeks to fight that?Huh....99.9% won't. And it WOULD have held it up while
you appeal to the state.


The NEC is a good start....but remember....it's a minimum.

KT4WO





Considering that stranded wire is normally rated for higher current than the same gauge solid wire, I would think that you would be more likely to fail solid ground wire than stranded.  The norm for nearly all installations I have ever worked on is stranded and according to my on-staff master electrician and RCDD is the preferred type of ground wire both from a current handling aspect and from a bonding aspect -- it being much easier to get a good bond with stranded than with solid.  And if I recall correctly, solid is forbidden for lightning aerial systems, though I'd have to dig back through the standards to be certain. 
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KT4WO
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Posts: 150


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« Reply #37 on: August 27, 2014, 06:11:11 PM »

Re:"Considering that stranded wire is normally rated for higher current than the same gauge solid wire"


Hmm..thought it was the other way around??....I could be wrong.
I know stranded is better for RF...but for power(120/12volts) it was solid.

Been out of that field for 10+ years.
Maybe it's just cheaper???(solid)

I have a 6ga solid ring around my house, 18 inches deep, with 7 ground rods that have 6" concrete on
the bottom 4 feet. I have never had a direct hit to test it, and hope I never do.
It is also bonded to the power co. (could be a mistake...but NEC says to)
I  DO NOT ground ANY of my ham equip. directly(coax/ground buss at tower)....EVERYTHING is outside....I don't
want it to come into the house.

And yes....all my connectors are crimped(then)soldered....if it melts the solder...the crimp will(may)hold.Huh

KT4WO

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KT4WO
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« Reply #38 on: August 27, 2014, 06:15:04 PM »

BTW....NEVER have inspected ANYTHING(ground) on a single or multi family home that had stranded.

Only commercial and up.

And that was BIG stuff that was bonded to a bunch of rods/ring.

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K1CJS
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Posts: 6034




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« Reply #39 on: August 28, 2014, 06:20:59 AM »

Re:"Considering that stranded wire is normally rated for higher current than the same gauge solid wire"

Hmm..thought it was the other way around??....I could be wrong.
I know stranded is better for RF...but for power(120/12volts) it was solid....

No, stranded is considered better for higher current.  It has to do with surface area of the wire, stranded wire supposedly has more surface area than the same gauge solid.
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K5TED
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Posts: 728




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« Reply #40 on: August 28, 2014, 02:24:38 PM »

The cross section area of stranded is equivalent to a solid conductor for the same designated wire size.

10AWG stranded will actually be slightly larger diameter than 10AWG solid wire because of the air spaces.

Since the strands actually touch each other, there is no "skin effect" advantage for the individual conductors surface area, but, as the stranded cable is actually slighter thicker than the same gauge solid wire, there is a slight increase in overall "skin" perimeter, therefore, a practically insignificant "advantage" at high frequency AC.

Skin effect is only relevant at high frequency AC, not DC grounding levels.

When using Litz wire, as the individual strands are insulated from each other, so the actual combined surface area is larger, there is a significant advantage over solid wire when used for high frequency AC. Litz wire is not a practical grounding solution.

Flat copper conductor is the good practice general RF grounding conductor of choice, with the exception of lightning arrestor (lightning rod) cabling, which by application needs to be braided to allow enormous instantaneous voltage and current conduction of both DC and high frequency AC.

Stranded wire of a given gauge is not a better conductor of current than a solid wire of same gauge, for all practical purposes.
« Last Edit: August 28, 2014, 02:26:46 PM by K5TED » Logged
KD0SFY
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Posts: 298




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« Reply #41 on: August 28, 2014, 05:58:06 PM »

The skin effect can exist within the air gaps of the wire, as well as on the extra surface area presented by the convoluted surface of stranded wire.

Much of the time grounding is not dealing with DC, but rather with various and sometimes complex wave forms, many of which can be higher frequencies.
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K5TED
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Posts: 728




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« Reply #42 on: August 28, 2014, 06:26:08 PM »

The skin effect can exist within the air gaps of the wire, as well as on the extra surface area presented by the convoluted surface of stranded wire.

Much of the time grounding is not dealing with DC, but rather with various and sometimes complex wave forms, many of which can be higher frequencies.


Facts and physics trumps lore every time.
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KD0SFY
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Posts: 298




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« Reply #43 on: August 28, 2014, 07:09:56 PM »

The skin effect can exist within the air gaps of the wire, as well as on the extra surface area presented by the convoluted surface of stranded wire.

Much of the time grounding is not dealing with DC, but rather with various and sometimes complex wave forms, many of which can be higher frequencies.


Facts and physics trumps lore every time.

Yes, they do. 
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K5TED
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Posts: 728




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« Reply #44 on: August 28, 2014, 07:23:55 PM »

so, either we squat around the eham campfire in our loincloths, peering fearfully into the surrounding darkness, muttering mostly incoherent and incongruous stories of the evil unknowns waiting to spring forth from the convolutions in the copper serpent's tail?

Or, do we admit all this faldera is for naught, wire behavior is a known quantity, grounding is straightforward and this discussion is about the correct wire gauge for station grounding, and not to dredge up fallacies, misconstructions, falsehoods and factually incorrect assertions?
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