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Author Topic: Insulators on ground bonding wire?  (Read 3721 times)
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K6JEK
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RF in the shack


« on: July 01, 2022, 01:21:42 AM »

How should I secure the #6 bonding wire from the antenna entrance panel to the service entrance panel? It runs in the house crawl space. Does this need to be insulated from the various wooden joists and such under there? I didn't see anything in the NEC code about this but admit I just perused it.

A little detail: Aluminum panel on the outside of the house with Alpha Delta static discharge units serving as bulkhead connectors. Ground rod right there connected to the panel and bonded to the service entrance ground with a run of #6. Do I need to do anything special as I secure this wire/

Thanks,

Jon
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K9MB
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« Reply #1 on: July 01, 2022, 10:44:34 AM »

I worry about this myself. A surge can lift a ground wire pretty high on a big discharge. Of course, a direct lightning strike will vaporize the wire and everything around it will be charred or worse.
I have run everything in Schedule 40PVC conduit. That should contain a lot of chaos,amd last tome I checked it was not too expensive compared to burned down house replacement…😉😂
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K6JEK
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« Reply #2 on: July 01, 2022, 01:10:47 PM »

I worry about this myself. A surge can lift a ground wire pretty high on a big discharge. Of course, a direct lightning strike will vaporize the wire and everything around it will be charred or worse.
I have run everything in Schedule 40PVC conduit. That should contain a lot of chaos,amd last tome I checked it was not too expensive compared to burned down house replacement…😉😂
Good idea and thanks for the price check on PVC.

I just thought of electric fence insulators. I may try these. At a buck thirty each they are still cheaper than a new house.  They are glass filled nylon.

https://www.zarebasystems.com/electrobraid-black-heavy-duty-line-post-insulators-20-pack-iwhdclawb-eb?SID=bd9272ad5393d2e281597ea4c2a30ac3
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W1ITT
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« Reply #3 on: July 01, 2022, 02:55:02 PM »

Jon... I'm curious as to why you run the ground bond inside the crawl space.  Is there something that constrains you from running it outside, along the edge of the foundation, or under the drips from the roof?  My inclination is to keep this bond wire outside of the building in the rare case that it might have to carry lots of current from a nearby strike.  It would be easy enough to bond at each end.  And if it were very long, I might even put at least one ground rod along the way.
The ground bond, if it is uninsulated could end up having lots of copper-to-soil contact along the way, which translates to a bit better coupling to "ground", at least during the wetter seasons.
A number of years ago I was involved in a grounding program at many of Uncle's worldwide HF sites and, besides copious rods in the ground, we interconnected all the rods with lots of 2/0 bare copper a couple feet down. The crew had great fun setting off all the CadWeld fireworks.     Of course, that was all done on the Taxpayers' credit card, but the point is that the interconnection can be your friend if you are on a tighter budget than our Uncle.  And you might have better luck keeping all those discharges out of the house.
73 de Norm W1ITT
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W1RKW
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« Reply #4 on: July 01, 2022, 04:01:54 PM »

Sched 40 PVC ain't cheap right now.  Nearly $50 for a 10ft length of 3 inch at Homies.
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Bob
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His fear was when I turned it on for the first time life on earth would come to a stand still.
K6JEK
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« Reply #5 on: July 01, 2022, 05:38:53 PM »

Jon... I'm curious as to why you run the ground bond inside the crawl space.  Is there something that constrains you from running it outside, along the edge of the foundation, or under the drips from the roof?  My inclination is to keep this bond wire outside of the building in the rare case that it might have to carry lots of current from a nearby strike.  It would be easy enough to bond at each end.  And if it were very long, I might even put at least one ground rod along the way.
The ground bond, if it is uninsulated could end up having lots of copper-to-soil contact along the way, which translates to a bit better coupling to "ground", at least during the wetter seasons.
A number of years ago I was involved in a grounding program at many of Uncle's worldwide HF sites and, besides copious rods in the ground, we interconnected all the rods with lots of 2/0 bare copper a couple feet down. The crew had great fun setting off all the CadWeld fireworks.     Of course, that was all done on the Taxpayers' credit card, but the point is that the interconnection can be your friend if you are on a tighter budget than our Uncle.  And you might have better luck keeping all those discharges out of the house.
73 de Norm W1ITT
That's an interesting idea, running it outside. I planned to put it in the crawl space because it's a straight shot while outside there is a lot of house in the way so it would be considerably longer with patios and such in between. But not crawling under the house has some real appeal.

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KD6VXI
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« Reply #6 on: July 02, 2022, 06:57:14 AM »

My two cents, as an electrician.

I put it outside.

The only connection that can be considered interior (on newi-sh homes) is where we bond for a Ufer.  And the concrete guys will look at the plans and see where we are putting the panel and bring a piece of rebar up in the wall at that location.  We have to put an access cover so the connection can be inspected and tightened up as needed.  This inspection hole is needed even on larger custom homes where cadwelds are used.

If water is iron pipe coming in we put that connection  outside as well.

Depending on your main breaker size #6 may or may not be sized large enough.

Where there is the possibility of damage you need to protect the ground electrode wire.  This can be as simple as some 3/8 MC cable sheath repurposed, some sealtite flex (pvc exterior, metal flex interior) or my favorite:  Some half inch PVC.

PVC is no longer 'cheap'.  I get, cheap is relative....  But it's no longer inexpensive in my book. On government installations I was working on back in the states we started dropping pvc pipe and going to fiberglass!  Stuff sucked as far as cutting it, but it was cheaper (by the foot.  I think it wqs a wash as it's a lot more labor intensive to install).

That ground wire has a tendency to vaporize if you have a very near or direct stroke hit.  That can cause nasties if your insulation in the attic is flammable.

An inspector may or may not approve.  An insurance inspector is sure to not approve.

All in all, a bad idea.

If you bury your copper make sure your soil isn't going to eat it up if it's non insulated wire.

--Shane
WP2ASS / ex KD6VXI
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Patrick J. / KD5OEI
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« Reply #7 on: July 02, 2022, 11:56:43 AM »

The spectacle of vaporization..   tables of interest:

AWG table includes 10s, 1s, and 32ms fusing currents for Copper wire.
https://en.wikibooks.org/wiki/Engineering_Tables/American_Wire_Gauge

fusing current (use as common electrical fuses) for Copper, Aluminum, Iron, and Tin.
https://www.powerstream.com/wire-fusing-currents.htm

In some countries there are renewable mains fuses for home and business, called Kit Kat fuses. One simply goes into the store and buys a card or a spool wrapped in a generous length of fuse wire, the rating of which is stated on said packaging, and replaces the wire in the fuse. A gentleman in India demonstrates the repair of such a fuse with un-sanctioned wire and with an approved fuse wire.
https://www.youtube.com/watch?v=025TZExHca4

I am not an electrician and this is not presented as electrical advice.
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Radio Candelstein - Flagship Station of the NRK Radio Network.
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« Reply #8 on: July 05, 2022, 12:13:55 PM »

the number 6 bonding wire doesn't need to be insulated from the wood beams  keep it away from water pipes.  the purpose of the wire is to reduce the voltage gradient between two sets of ground rods in the ground at different locations  run the ground wire by the most direct route  lightning doesn't like to go around corners  the wire can be bare or with an insulation cover

fred
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K6JEK
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« Reply #9 on: July 08, 2022, 01:59:10 PM »

Lightning is rare here in Santa Clara County, CA. How rare? I haven't had much luck finding historical strike data. Does anyone know a good source?
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WB6NVH
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« Reply #10 on: July 11, 2022, 10:04:22 PM »

I was just going to say that.  Lightning, rain, snow, what are those when you live in Santa Clara, Santa Cruz and Monterey Counties.  We did have heat lightning strikes one July a couple of years ago taht started forest fires but they were above the 4000 foot level.
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Geoff Fors
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« Reply #11 on: July 12, 2022, 06:50:32 AM »

I went to high school in Santa Cruz.  Class of 1990.

We had lightning.

Maybe not as often as we did when I lived in the Mojave desert area, but lightning was a fact of life there too.

May e it has changed some?  I lived in Boulder Creek for a few years in the early 2000s, I don't seem to remember as much then.

The complex fires would beg to differ that lightning isn't an issue in the area though.

As well as Big Sur.

Only takes one stroke and it's all over.


--Shane
WP2ASS / ex KD6VXI
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K9MB
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« Reply #12 on: July 12, 2022, 10:56:39 AM »

A direct strike is a different animal from a spark or surge on the grid.
My nephew had a nice house on a hill and one day, it suffered a direct hit that blew a large hole in the roof and instantaneously ignited the roof and house frame and fused all the wiring and the house burned down.
If one of those hits you, just ne grateful you get out alive. Thankfully, they are not common…
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K6JEK
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RF in the shack


« Reply #13 on: July 13, 2022, 11:34:39 AM »

A direct strike is a different animal from a spark or surge on the grid.
My nephew had a nice house on a hill and one day, it suffered a direct hit that blew a large hole in the roof and instantaneously ignited the roof and house frame and fused all the wiring and the house burned down.
If one of those hits you, just be grateful you get out alive. Thankfully, they are not common…
Yikes.

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