In message , Gareth's Downstairs Computer
writes
On 06/09/2018 13:59, Rambo wrote:
On Thu, 6 Sep 2018 11:46:55 +0100, Gareth's Downstairs Computer
wrote:

Unearthed the previous fan of plumbers' copper microbore tubes
and associated ground rod to find a corroded and non conductive
mess and raised the question of how to protect underground
junctions from the worst that nature could throw at them?

Firstly, resurrecting a technique from school metalwork lessons
from 53 years ago when brazing things together, dig out the
gas torch, soldering flux***** and solder and connect all together
electrically.

Secondly, to protect the now-relatively-massive joint, smear with
petroleum grease. Was this a good idea, and is there something better?

***** Curious as to whether could be combined with one's radio
interest to nake a flux capacitor to go time travellingg :-)


cathodic protection?


Interesting because between the house TT earth, a steel rod and the
copper RF earth is now about 0.4 volts, making the ohmmeter go haywire
trying to measure the resistance between them.

One way of assessing the effectiveness of an earth rod is to apply (from
a transformer) an isolated low AC voltage between it and (say) the mains
earth - and measure the current. Obviously, you've got to take into
account the resistance of the connecting wires.
--
Ian