On Friday, April 17, 2020 at 3:42:51 AM UTC-5, micky wrote:
Do copper or copper-clad steel ground rods disappear with time?

After 37 years, does mine need replacing?

When I put in my first burglar alarm, 37 years ago, I put in a ground
rod to ground the system, and iiuc reduce the chance of lightening
damage. (Nonetheless, after about 20 years, when I was leaving for
work, there were wisps of smoke coming from the keypad/control usit, and
it never worked again. ;-) I have a new alarm now, grounded to the same
rod, but something told me the rod was gone. The top of it is still
there so maybe I dreamed it, but is it likely that the part above ground
is there but most of it below ground is gone, and needs replacing?

Well, it might not be too difficult to dig down a foot or two next to
the rod to inspect it that far. You can always add another rod next to
the first one, and many people have several rods. The more the better.