Grounding rod question 15/45A PEA

[MJCM]

We are "modernising" the house next door we have bought several years ago.

 

One of the changes is redoing ALL the old electrics to include RCBO's etc etc/

 

The Old grounding rod was placed directly next to the wall of the house and then covered in concrete leaving only a small "stump" uncovered.

 

Now we want to place another grounding rod on the other side of the wall (approx 100cm from the wall). This side is close to where the CU will live.

 

The OLD grounding rod will not be connected up.

 

Is there an issue with leaving the old grounding rod in place or not. Removing the OLD one will be a "big" task as we have to break away all the concrete etc etc.

And another question, we will connect 10mm² copper to the grounding rod is that sufficient or should we go bigger (Supply is 15/45A)

 

TiA

 

[Crossy]

No issue leaving the old rod in place.

 

If there's a metre or so between the rods why not hook them together directly rod to rod (not via your CU)?

 

Multiple rods can be an issue if they are far enough apart for significant ground potentials but a metre or so would work like one rod.

 

I'd make the cable to the rod the same size as your incoming supply cable since we are TNC-S (UK would say 16mm²), bigger never hurt

[MJCM]

My bad, that I wasn't clear enough.

 

The other (old) rod is on the other side of the house next to the wall (direct distance between them is around 10 meters (with walls in between them)) (So "old" rod is located on the left side of the House, new rod right side of the house)

 

[Crossy]

Just now, MJCM said:

My bad, that I wasn't clear enough.

 

The other (old) rod is on the other side of the house next to the wall (direct distance between them is around 10 meters (with walls in between them)) (So "old" rod is located on the left side of the House, new rod right side of the house)

 

 

OK, then don't connect it, but there's definitely no issue with leaving it in

[MJCM]

6 minutes ago, Crossy said:

I'd make the cable to the rod the same size as your incoming supply cable since we are TNC-S (UK would say 16mm²), bigger never hurt

 

I still have some lengths of 25mm² NYY Copper left from the install of our current house, will use that.

 

The Grounding Rod is approx 2,20m+ long is that enough?

[Crossy]

2 minutes ago, MJCM said:

I still have some lengths of 25mm² NYY Copper left from the install of our current house, will use that.

The Grounding Rod is approx 2,20m+ long is that enough?

 

PEA say >=2.4m but who will know once it's in the ground

 

[MJCM]

Wow thx for the pic.

 

Will show this to the sparky tmrw and PEA when they come to inspect :

[Crossy]

13 minutes ago, MJCM said:

Wow thx for the pic.

 

The rest of the PEA document, always handy to have: -

 

Groundwire Mk2 book-Manual.pdf

 

The important diagram, my translations.

 

 

[Morch]

@Crossy

 

Our 'electricians' (semi-retired absent minded father, and his textile-college graduate son) hated you. Every argument we had ended up with 'Crossy said!' (in English). Heard them muttering about it, trying to figure what it meant.

 

The elder was actually into most 'upgrades', as he didn't do much of the hard labor. Junior wasn't appreciative of the 2.4 pole, though.

[Crossy]

1 minute ago, Morch said:

Every argument we had ended up with 'Crossy said!' (in English). Heard them muttering about it, trying to figure what it meant.

 

I'd better watch my back for paid assassins then

[MJCM]

4 minutes ago, Morch said:

@Crossy

 

Our 'electricians' (semi-retired absent minded father, and his textile-college graduate son) hated you. Every argument we had ended up with 'Crossy said!' (in English). Heard them muttering about it, trying to figure what it meant.

 

The elder was actually into most 'upgrades', as he didn't do much of the hard labor. Junior wasn't appreciative of the 2.4 pole, though.

 

555555555555555

 

My argument with them ends with "the guy that works for the BTS and takes care of all their electrics" and that usual shuts them up (with that I also mean @Crossy of course 555555) (I also mention he is a Farang, which adds a extra weight around "Baan Nork")

[Crossy]

2 minutes ago, Morch said:

Junior wasn't appreciative of the 2.4 pole, though.

 

This is where an SDS rotary hammer and our home-made adaptor came in handy. I made the adaptor from a cheap SDS chisel, 10 minutes on the lathe

 

[brianthainess]

33 minutes ago, MJCM said:

 

I still have some lengths of 25mm² NYY Copper left from the install of our current house, will use that.

 

The Grounding Rod is approx 2,20m+ long is that enough?

 

26 minutes ago, MJCM said:

Wow thx for the pic.

 

Will show this to the sparky tmrw and PEA when they come to inspect :

PEA must be able to read the stamp on the new rod, just saying as I'm not quite sure what you mean by NYY copper left over.

[Morch]

5 minutes ago, Crossy said:

 

I'd better watch my back for paid assassins then

 

If they are as good assassins as they were good electricians, nothing to worry about.

Guy across the street is a pretty senior PEA official (runs three amphurs), should have asked him for a guy before relations soured.

[MJCM]

11 minutes ago, brianthainess said:

I'm not quite sure what you mean by NYY copper left over.

 

We live in the House next door and when we build this house we pulled 25mm² NYY Copper from the Meter to the House and from the 200M (2 rolls) I bought back then I still have some considerable (pricey I believe)) lengths available, did not use them all. So that is what we are going to use

 

Edit: To avoid confusing (we are doing the house next door and using left over cable (NYY) from the house we live in

[Crossy]

25 minutes ago, brianthainess said:

just saying as I'm not quite sure what you mean by NYY copper left over.

 

This: -

 

https://www.bangkokcable.com/system/product/file_upload/211102_450!750V 70C NYY_1-4core_Rev04.pdf

 

 

[Crossy]

25 minutes ago, brianthainess said:

PEA must be able to read the stamp on the new rod, j

 

Sorry Mr PEA, the required exothermic weld melted the stamp

 

Our man didn't get close enough to the rod to see anything other than it being a copper-clad steel rod.

[MJCM]

7 minutes ago, Crossy said:

 

Sorry Mr PEA, the required exothermic weld melted the stamp

 

Our man didn't get close enough to the rod to see anything other than it being a copper-clad steel rod.

 

55555555555555555

 

In our old house, the PEA guy (same guy who did the inspection on our current house) just looked at the "isolator", safety cut , and CU and just nodded his head and signed off on it. (This is approx 8 years ago). He didn't even bother to look at the rods etc or ask any questions.

 

It was even worse (If I can say that) at our current house, he didn't even come inside, he just connected the "permanent" meter up (we were using the construction meter with the increased rates) up on the road and just was chit chatting away with with Sparky and SWMBO and did NOT bother to come in and check.

 

Baan Nork springs to mind

[bluejets]

13 hours ago, Crossy said:

If there's a metre or so between the rods why not hook them together directly rod to rod

Would be frowned upon in many countries due to requirements for one main earth point only.

Would interfere with certain test proceedures and leave the test technician scratching their head.

A big no-no down under and probably many other places as well.

 

A bit like the "manual" float switch we had as temporary during a PLC fitout on the Dawson River pump station a few years ago.

Old German programmer was about to begin to re-write all his software thinking there was an error.

 

As for main earth cabling size, it is regulated the size of the mains.

So if copper and 16 square mm , earth would be 6 square mm.

I very much doubt any domestic install would need to be any larger than that.

After all, in the MEN system, it's a means of pegging the supply to ground potential.

The portion between the n/l and the ground rod, as long as no sub circuit earths are connected between, carries no fault current.

[Crossy]

9 minutes ago, bluejets said:

Would be frowned upon in many countries due to requirements for one main earth point only.

 

Yeah, this is where the regs around the world can differ.

 

Multiple rods are fine under UK regs (with certain constraints) if needed to get the earth resistance down to an acceptable level, the interconnect from the CU to the array of rods being treated as the main earth point. We tend only to have rods on TT installations anyway, relying on the PEN or PE (if it's TNS) conductor.

 

You are of course only permitted one Main Earth Terminal (MET) where all your installation earths go. 

[Sophon]

14 hours ago, brianthainess said:

 

PEA must be able to read the stamp on the new rod, just saying as I'm not quite sure what you mean by NYY copper left over.

 

The stamp on the ground rods here (maybe surprisingly) doesn't necessarily indicate the exact length of the rod.

 

Stamp on a 2.4m ground rod:

 

Stamp on a 2m ground rod:

[bluejets]

23 hours ago, Crossy said:

Multiple rods are fine under UK regs (with certain constraints) if needed to get the earth resistance down to an acceptable level, the interconnect from the CU to the array of rods being treated as the main earth point. We tend only to have rods on TT installations anyway, relying on the PEN or PE (if it's TNS) conductor.

 

You are of course only permitted one Main Earth Terminal (MET) where all your installation earths go. 

Yes, to be fair and clear in the description, earth grids are used here as well BUT not in what would be considered "standard" installations, be it domestic, commercial or industrial.

Grids, as you point out, only have the one MEN connection but are largely confined to supply authority HV transformer yards.

There is no need or requirement to have ground resistance included in any installation inspection etc. 

Bit off subject but only variation on that was the install of a lighting protection system with isolated earths at a local hospital.

Interesting to note that this was 20 years ago and checking the strike counter some weeks ago has revealed a zero strike count.

I think it was more related to the architect trying to score brownie points with design.

I have seen/installed earth grids in coal mining situations where the ground resistance is upta crap........they are restricted to mine systems which are not connected to what is normally considered the supply authority grid, usually at punch mine with generator supply but this has more to do with coal mine strict requirements regarding any above earth voltage rise (for obvious reasons).

[MJCM]

On 12/9/2023 at 6:17 AM, bluejets said:

As for main earth cabling size, it is regulated the size of the mains.

So if copper and 16 square mm , earth would be 6 square mm.

 

The Mains cable (coming from the meter) is 25mm² ALU so what would then be the earth size be?

 

And another question, is in this case the bigger the cable the better?

[bluejets]

On 12/11/2023 at 9:34 AM, MJCM said:

The Mains cable (coming from the meter) is 25mm² ALU so what would then be the earth size be?

6 square mm copper.

[Crossy]

1 hour ago, bluejets said:

6 square mm copper.

 

That would satisfy Aussie regulations.

 

BUT.

 

Thai regulations require a minimum of 10mm² to your rod.

 

UK regs actually want a (way over-sized in reality) minimum of 16mm² to the rod (BS7671 18th edition, Regulations 543.1.2 - 543.1.5) as does the US NEC.

 

It's always best to verify with local regulations., usually our Western/Aussie regs easily satisfy or exceed the local ones but ...

 

From this PEA document Groundwire Mk2 book-Manual.pdf

Page 7 of the .pdf, clause 2

 

 

Groundwire Mk2 boo

 

 

 

 

[MJCM]

Oke but the second question I asked, is the bigger the better (in square mm) in this case better or not?

[digbeth]

On 12/8/2023 at 4:56 PM, Crossy said:

 

PEA say >=2.4m but who will know once it's in the ground

 

 

The Thai wording specify that copper rod, copper clad iron/steel rod or zinc plated steel rods are acceptable, 

but in the end they say they don't allow iron sheathed steel rods due to the possibility of the copper riding up against the dirt exposing the core resulting in corrosion.

 

What exactly is the difference between copper clad or sheathed are they talking about? most of the ground rods I see in homepros has exposed steel heads you can drive in the ground, but I have seen case when hammering the rod down and the side were against some concrete in the ground that tore the copper and bunch up the copper up the rod which is why the regulation is trying to guard against here... 

[Crossy]

3 hours ago, MJCM said:

Oke but the second question I asked, is the bigger the better (in square mm) in this case better or not?

 

Bigger never hurts

[Crossy]

4 hours ago, digbeth said:

 

The Thai wording specify that copper rod, copper clad iron/steel rod or zinc plated steel rods are acceptable, 

but in the end they say they don't allow iron sheathed steel rods due to the possibility of the copper riding up against the dirt exposing the core resulting in corrosion.

 

What exactly is the difference between copper clad or sheathed are they talking about? most of the ground rods I see in homepros has exposed steel heads you can drive in the ground, but I have seen case when hammering the rod down and the side were against some concrete in the ground that tore the copper and bunch up the copper up the rod which is why the regulation is trying to guard against here... 

 

A good question which I admit I had never thought about, just assumed (always a bad idea) that "copper clad" and "copper sheathed" were synonymous.

 

This is what Bard AI has to say on the subject: -

 

=================================================

 

While the terms "copper clad steel" and "copper sheathed steel" are sometimes used interchangeably, there are subtle differences between the two. Here's a breakdown:

Copper Clad Steel:

• Bonding method: The copper layer is mechanically bonded to the steel core using heat and pressure. This creates a tight bond, but it can be susceptible to cracking or peeling if subjected to high stress or extreme temperatures.
• Copper thickness: The copper layer is typically thinner than in copper-bonded steel. This allows for greater flexibility but reduces conductivity.
• Applications: Copper clad steel is commonly used in stranded conductors, wire mesh, and applications where flexibility is important.

Copper Bonded Steel:

• Bonding method: The copper layer is bonded to the steel core through an electroplating process. This results in a more uniform and corrosion-resistant bond than in copper-clad steel.
• Copper thickness: The copper layer is thicker than in copper-clad steel, which improves conductivity. However, this can make the rod less flexible.
• Applications: Copper-bonded steel is primarily used in ground rods, solid wire, and applications where high conductivity and corrosion resistance are critical.

Here's a table summarizing the key differences:

Feature	Copper Clad Steel	Copper Bonded Steel
Bonding method	Mechanical	Electroplating
Copper thickness	Thinner	Thicker
Flexibility	More flexible	Less flexible
Conductivity	Lower	Higher
Corrosion resistance	Good	Excellent
Applications	Stranded conductors, wire mesh	Ground rods, solid wire

Ultimately, the best choice for your application will depend on your specific needs. If you need a flexible conductor with good conductivity, copper clad steel may be a good option. However, if you need a high-conductivity and corrosion-resistant ground rod, copper-bonded steel is the better choice.

[bluejets]

On 12/14/2023 at 9:58 AM, Crossy said:

That would satisfy Aussie regulations.

 

BUT.

 

Thai regulations require a minimum of 10mm² to your rod.

Possibly due to their using solid rather than the more flexible, stranded conductors we use in Aus.

Either way, 6mm square is the Aus standard as you say, but take a look around you at the rest of Thai wiring.

I wouldn't be too quick to condem Aus regs.