Earthing Problems

[Onoff]

Looking to improve the TT arangement at my house. 6A prospective fault current to earth isn't the best!

There was a 4' 3/8" rod in the ground. Changed that to a 4' 5/8" rod, made no difference. Added another 4' 5/8" rod, spaced > one rod's length from the first. Still no better.

The ground here is thin soil, clay then chalk.

Next step is to couple another rod on and try and go 8' deep. Not expecting much if I even manage to get it in

I was thinking maybe an earth mat.

It's £138 for a ready made 900x900 one. Or an old, flattened, copper HW cylinder.....

 

[dobbslc]

I've used old galvanized Hiras fence panels on site in a pinch where some retard has dug up the rods and they do give a vastly improved earth electrode reading, these are temporary installations though

In poor soil conditions you can use Bentonite compound to improve the moisture content of the local area. https://www.powerandcables.com/product/earth-tapes-rods-bars-copper/bentonite/
On chalk soil you're always going to struggle though.

 

[Onoff]

Half mulled flattening some 22mm copper pipe with a digger and making my own mat with copper rivets.....not worth thd effort I don't think.

If deeper/more rods don't work I'll probably stump up for this:

Electric Vehicle Charging Point Earth Mat Kit – Churchill Specialist Contracting

www.churchillsc.co.uk

As an aside I've a reel of 9x1mm copper tape, have wondered in the past about laying that all the way down the garden in my yet to be filled, water main trench then back filling. I got as far as laying the new 20mm MDPE main in a gravel bed. It's in it's own (blue) corrugated duct too. The intent was to run a green corrugated duct for CCTV at the boundary. Never happened of course and nature has filled thdvtrench in a bit of it's own accord. Will need clearing out at some time I guess!

Said trench:

https://flic.kr/p/MLjmNj

Roadside water meter:

https://flic.kr/p/NF4s5d

 

[gaz1]

you dont need that

use a galvanised pipe and poor water into it

Grounding Installation (Step by Step Guide)...

What is Grounding or Earthing? To connect the metallic (conductive) Parts of an Electric appliance or installations to the earth (groun...

onebyzeroelectronics.blogspot.com

 

[Onoff]

I've used old galvanized Hiras fence panels on site in a pinch

Seem to recall that at Dungeness nuclear plant they excavated the beach shingle and laid one great big mat!

 

[Onoff]

you dont need that

use a galvanised pipe and poor water into it

Grounding Installation (Step by Step Guide)...

What is Grounding or Earthing? To connect the metallic (conductive) Parts of an Electric appliance or installations to the earth (groun...

onebyzeroelectronics.blogspot.com

Like my BiLs garage earth, scaffold pipe with the earth wire attached by mole grips!

 

[dobbslc]

The copper tape will work, surface area is king here but the soil drying out near the surface is a problem.

 

[gaz1]

Like my BiLs garage earth, scaffold pipe with the earth wire attached by mole grips!

whilst many look at it, as being stupid it has more area to ground than your silly bar that your using

whilst the water inside of the tube adds moisture it also upgrades the earthing capacity of the pole rather than your bar that your using

 

[Onoff]

The copper tape will work, surface area is king here but the soil drying out near the surface is a problem.

You can just see where the two earth rods are. As temporary "pits" I cut some grey, 200mm dia pvc pipe. I'll make it all neat and tidy once (if) I get the readings down.

The rod nearest the house, I've damaged the 5/8" BSW thread on top so can't get a coupler on to add another rod. Have ordered a die nut. Second rod I found some 5/8" full nuts to beat down on!

Original rod position near house:

Second rod:

This is what I have at the moment:

 

[Onoff]

The copper tape will work, surface area is king here but the soil drying out near the surface is a problem.

It's pretty shaded by trees and one section likely kept wet by the leaky old cess pool!

 

[Onoff]

Tonight I'll attempt to add another 4' rod to the furthest one away.

 

[Dee J]

Looking to improve the TT arangement at my house. 6A prospective fault current to earth isn't the best!

There was a 4' 3/8" rod in the ground. Changed that to a 4' 5/8" rod, made no difference. Added another 4' 5/8" rod, spaced > one rod's length from the first. Still no better.

The ground here is thin soil, clay then chalk.

Next step is to couple another rod on and try and go 8' deep. Not expecting much if I even manage to get it in

I was thinking maybe an earth mat.

It's £138 for a ready made 900x900 one. Or an old, flattened, copper HW cylinder.....

6 amp prospective fault current... But what does your protective device need to trip? 100mA? What sort of figure are you aiming for?

 

[dobbslc]

100ma will be an RCD, an RCD won't trip with an overload fault like a short between live and neutral on a final circuit or a fault between live to neutral within the dist board where you'd want the service cutout fuse to blow.
I'm on an earth rod and will have a look at the test I did from a couple years ago to see what I've have recorded. The earth electrode varies between about 17-21 ohms here depending on time of year.

 

[brightspark]

100ma will be an RCD, an RCD won't trip with an overload fault like a short between live and neutral on a final circuit or a fault between live to neutral within the dist board where you'd want the service cutout fuse to blow.
I'm on an earth rod and will have a look at the test I did from a couple years ago to see what I've have recorded. The earth electrode varies between about 17-21 ohms here depending on time of year.

thats decent as long as his rod readings are under 100 ohms thats well acceptable on

 

[Onoff]

Got home and coupled another 5/8" rod to the rod furthest away from the house. Tried hammering it in. Went a few inches and stopped. Tried a blunt ended SDS on it with the drill on hammer. Wouldn't have it. Presume I've hit a bfo flint or the chalk layer!

Put a 3rd rod in greater than one rod's length from the second. Seemed to go in easier than the first two so thinking the ground is a bit wetter as it's further away from the house.

Three rods:

Middle rod, damn thing is a bit too far in now, this the one that hit something:

Rush job as getting dark, it's thrown in pretty much. On the last rod I had no 16/10 uninsulated ring crimps so it's got a 50/10 hammered on!

Then had a brand new, unopened bag of 16/8 ring crimps, opened them up and they're 10/8!

Little video of the earth loop impedance testing:

https://flic.kr/p/2omXNVm

 

[Onoff]

I might try and add another 4' rod to rod No.3...

 

[Dee J]

100ma will be an RCD, an RCD won't trip with an overload fault like a short between live and neutral on a final circuit or a fault between live to neutral within the dist board where you'd want the service cutout fuse to blow.
I'm on an earth rod and will have a look at the test I did from a couple years ago to see what I've have recorded. The earth electrode varies between about 17-21 ohms here depending on time of year.

Hmmm. Don't quite get you. The earth rod is only relevant in earth fault situations, not L-N overload. And any TT install should have an RCD for earth fault and mcb for overload.

 

[Onoff]

6 amp prospective fault current... But what does your protective device need to trip? 100mA? What sort of figure are you aiming for?

All my breakers btw are Type 1 & 2 Crabtree C50s. Well old! I haven't got tables for those. The circuit I'm testing on, the kitchen ring, is on a 30A C50 breaker but I've no idea if it's Type 1, 2 etc without taking it out.

 

[brightspark]

All my breakers btw are Type 1 & 2 Crabtree C50s. Well old! I haven't got tables for those. The circuit I'm testing on, the kitchen ring, is on a 30A C50 breaker but I've no idea if it's Type 1, 2 etc without taking it out.

have you the 30ma rcd fitted though if its a tt system .it should have on a domestic property

 

[Onoff]

have you the 30ma rcd fitted though if its a tt system .it should have on a domestic property

Yes, there's an upfront 30mA RCD protecting all 9 circuits. I keep meaning to change the cu but want to put a new, all (double pole) RCBO one inside. At the moment it's in the open porch where it sits tight up against the ceiling.

I'll have to fit a switch fuse as I'd need to extend the tails from that REC2 beyond 3m.

https://flic.kr/p/2omWzpB

Of course SWMBO and I have different ideas as to where the new cu should go! My way means moving an internal doorway.