fluctuating readings on a tt rod

[Gavin John Hyde]

Been at a rural cottage today doing a pre install survey for a EV charger,
House is 400 and something years old and situated on a hill with lots of rocky ground, mainly limestone based rocks. Owner tells me the rod is in his own words ' two joined together to make a long one' as he helped bang it in.
The following are taken from certs they have from previous work
Jan 17 - 140 ohms
July 17 - 274 ohms
Dec 17 - 128 ohms
3rd Feb 18 - 112 ohms - Measured by myself
Today 355 ohms!!!
The ground is very dry and even digging down a foot quickly with a spade the ground is dry. little if any damp. Any moisture quickly goes down the hill the property is situated on. the ground is hard rocky and little actual soil.
Certainly fluctuates with the seasons.. can't help but think this prolonged dry spell has impacted the reading..
its got me thinking about whether to put another rod in as we are told anything above 200 ohms is 'unstable'
Down side is not sure how on earth I get a rod in when the ground has so little soil etc... might be spending some time playing with the SDS!
What would you guys do? earth plate or tape? as this reading is not ideal

 

[Wilko]

In college i was told the rods had to be a minimum of 1 metre from the dwelling. What is the reasoning for this as that was never actually explained

Interesting ... Maybe it's to ensure the rod is away from any gravelly backfill around the foundations (?).

 

[Strima]

Interesting ... Maybe it's to ensure the rod is away from any gravelly backfill around the foundations (?).

Foundations won't help maintain a good sphere of influence: Grounding Electrode Sphere of Influence - E&S Grounding - http://www.esgroundingsolutions.com/grounding-electrode-sphere-of-influence/

 

[Gavin John Hyde]

I take it DNO can’t provide a PME connection?

No, It wouldn't help me in any case as i am installing a EV charger so would still have to put a rod or two in as I would be exporting the PME outside. Pretty much all of the village is TT or at one end near a main road they are TNS. never come across PME around there.