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Author Topic: Copper Strap Bonding  (Read 1038 times)
WX7K
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Posts: 45




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« on: April 28, 2008, 09:10:47 AM »

I just got this reply back from the sales rep at Georgia Copper when I asked about bonding copper strap to the ground rod.  My question is:  is there enough surface area at the physical connection to safely dissipate a lightening strike or do you need to bond the full width of the strap to the rod?

"Yes, silver brazing rod requires more heat than a regular propane torch can provide.  I have not personally used a mapp torch, but it is supposed to provide sufficient heat for silver brazing.  I have always used an oxyacetylene torch.
 
Here are a couple of ideas on connecting to the ground rods....  
 
You can cut about halfway across the width of the strap with sheet metal shears.  Then, cut out a circle in the middle of the strap about the diameter of the ground rod (or a little smaller).  Or instead of a circle in the middle of the strap, you can cut an asterisk shape.  Then work that hole around the ground rod and braze it to the rod.  The end result is a strap laying flat on the ground with a little bit of rod sticking up in the middle of the strap.  And of course everything is brazed together.
 
Another method I have used is easier, and probably just as good.  Let the strap lay right beside the ground rod (strap is laying flat on the ground, and a little bit of ground rod is sticking up out of the ground right beside the strap - edge of strap touching the rod).  Bend a piece of solid, bare copper wire, about a #6 or #4 awg into a U shape so that the bend of the U fits snuggly around the rod and then let the straight parts of the U lay on the strap.  Braze that all together.  
 
Wire, of course, has higher inductance than strap, but that tiny bit from the rod to the strap is so short it should be fairly insignificant..... besides, there are two wires in parallel (both straight parts of the U shape)"
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K9KJM
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Posts: 2416




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« Reply #1 on: April 29, 2008, 01:32:29 AM »

A small hand held torch with MAPP gas produces plenty of heat to flow the hard silver/copper/nickel rod when working with the copper strap, Or wire up to about #4 gauge......... However,
Trying to weld to a ground rod, especially when the rod has already been driven into the ground will require the oxyacetylene torch.

I have used the trick of pre welding #6 solid wire to the rods in the shop with the oxyacetylene torch, Then when the rods are driven in the ground out in the field, The little hand held MAPP gas torch will weld the #6 to the copper strap no problem. I agree that is a good way to do it.

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