Earth electrode tester or not?

[D Skelton]

I don't get paid good money to run multi million dollar projects by spouting rubbish!! I'll leave all the rubbish spouting, to the clever but lazy buggers that openly wouldn't even try to install a decent TT system, and fall back on the crap that written in the BGB...

There are plenty of people earning good money and running large projects who know sweet FA! I'm not implying that's you, but you can't use the fact that you run big projects to make your views any more worthy than anyone elses. I run big projects, but according to you I'm one of the 'lazy buggers'.

You talk of 'decent' TT systems, but what EXACTLY is the difference between how a stable 10ohms and a stable 200ohms protects an installation? Both RELY on RCDs!!!!!

When it comes to a gardn shed, I'll happily rely on a couple of RCDs, when it comes to a larger commercial/agricultural installation I will keep banging rods in until I get a TN value. I choose to install my rods in both of these ways not because I'm happy with what the BGB is telling me, I couldn't give a monkeys. I choose to install in this way because I am happy to rely on the science and principles of electrical installation work and very simple maths, this doesn't make me lazy in any shape or form, nor does the instances where I am happy to rely on RCDS make my work any less worthy than yours, it simply makes me cost effective!

Mrs Jones isn't paying for 'multi million dollar' protection on her shed, she is paying for something that works and that is perfectly safe. (And before you say it won't cost a million dollars to achieve sub 10 ohms, I know, but time IS money).

 

[Silly Sausage]

I'm not going to question E54's credentials for a second, but I wish he'd backup some of his statements sometimes.
Just a link to a reference would do, I don't expect a thesis posting on a topic!

 

[Engineer54]

There are plenty of people earning good money and running large projects who know sweet FA! I'm not implying that's you, but you can't use the fact that you run big projects to make your views any more worthy than anyone elses. I run big projects, but according to you I'm one of the 'lazy buggers'.

You talk of 'decent' TT systems, but what EXACTLY is the difference between how a stable 10ohms and a stable 200ohms protects an installation? Both RELY on RCDs!!!!!

When it comes to a gardn shed, I'll happily rely on a couple of RCDs, when it comes to a larger commercial/agricultural installation I will keep banging rods in until I get a TN value. I choose to install my rods in both of these ways not because I'm happy with what the BGB is telling me, I couldn't give a monkeys. I choose to install in this way because I am happy to rely on the science and principles of electrical installation work and very simple maths, this doesn't make me lazy in any shape or form, nor does the instances where I am happy to rely on RCDS make my work any less worthy than yours, it simply makes me cost effective!

Mrs Jones isn't paying for 'multi million dollar' protection on her shed, she is paying for something that works and that is perfectly safe. (And before you say it won't cost a million dollars to achieve sub 10 ohms, I know, but time IS money).

Really, well i haven't come across Any, you don't get to be running large projects by knowing FA, you'd be found out in very quick order!!

Now no-one has stated, including myself, that this could well be the case. What i've always stood up to on these threads, are those that tend to poo, poo anything that involves a little work in actually trying to achieve those ''not impossible'' sub-1 ohm TT systems. Then try to distort anything that's been said, that doesn't suit their lazy attitude in support of the crap quoted in the BGB/OSG!! As far as where sheds and garages are concerned, ..there would have to be a dammed good reason, why i would TT them in the first place, leaving a perfectly good TN earth behind!!

So what's your problem with stipulating 2 X 5/8'' or a single 2.4m 5/8'' rods as the minimum length and size of rod to be used in creating a TT system?? You keep going on about the ohm values achieved, when in actual fact it's the stability of the system that should be considered initially, the usually lower ohm value associated with this set-up, is a welcome plus or bonus!! Now when you think about it, the overall length and size of the above rods is very close to those earth rods (10') that were once considered ''the standard'' in the UK!!

Now, having said that, if i saw a value of say 10 ohms after driving in those 2 X rods, it would be a no-brainer for me too attach a third rod and drive that in. Then i would be looking/interested at the ohmic value of the completed installation, as my stability would have been substantially achieved with the initial 2 X rods, and i'd know that my Ra would initially be, in the very low single figures or better, and which, will continue improving over the next 12/18 months or so as the soil consolidates around the upper 2 rods!! But that's me, and it's not going to cost a fortune either. Now tell me that isn't worthwhile!!

People are quite right about my reluctance to rely on the reliability of RCD devices, i have good reason too!! Which is why i have always recommended, (because of the reliability problems associated with single RCD's set-ups), that an up-front 100/300mA S type device be installed to give at decent degree of back up protection, if and when the normal 30mA fails to operate under fault conditions....

Now it seems that a few are very quick in coming up with arguments for not making an effort, maybe it may time to start thinking of arguments for making a bit of an effort, when it comes to creating a TT system... Some maybe pleasantly surprised, that it doesn't take that much of an effort, than they thought!!

 

[D Skelton]

I would never 'poo poo' anyone for trying to achieve a sub 1ohm TT, what I will poo poo is anyone who says 10/20/30/40ohms is better than 200! I keep saying time and time again, there is NO inbetween! Either rely on a RCD (quite rightly backed up with a type-s), or, get a sub 1ohm value and use that as your back up! Depending on the circumstances, I have done both and will continue to do so. I also maintain that I have never left a TN connection behind unless exporting has not been permitted.

I have no argument against stability, however the value in the regs of 200 ohms is seen to be the absolute maximum value to work to to guarantee that system won't go over 1.6kohms. That value is there for a reason and I'm sure various tests have been conducted to confirm this. I can see how you think every ohm under 200 is a bonus, and in a way, I would have to agree, but in the same way that if you were diagnosed with a terminal illness, every second you lived from that moment on would be a bonus, but at the end of the day the same thing is going to happen!

What I don't get is this notion that if you achieve a value of 200 ohms or less and it is STABLE, as it most likely will be! The OP is testament to this! That it is still somehow a crap value when in reality it will achieve exactly the same function as a value of 10ohms!

If you're happy to rely on two RCDs (a normal and a type-s) with a value of 200 ohms then I cannot see for the life of me how this would make someone lazy!?!

What makes someone lazy (and dangerous) in my opinion is the idiot that comes along with a complete lack of understanding in how a TT system operates and whacks in a new CU, no type-s in sight and leaves their meter long twig sticking half out of the ground. Myself, WP and anyone else for that matter who sees a TT system like we do isn't lazy, nor are we dangerous, because (contrary to what you might THINK) we do hold a fundamental understanding of how TT systems work and are more than prepared to adapt our working practices inline with the regulations and in line with our understanding of electrical theory to suit each individual set of circumstanses.

Edit: I might add also that just because I disagree with some of what you say on this subject, it doesn't mean that I don't respect or value your opinion. I would hope that the same would be true of you.

 

[Jay Sparks]

I would never 'poo poo' anyone for trying to achieve a sub 1ohm TT, what I will poo poo is anyone who says 10/20/30/40ohms is better than 200! I keep saying time and time again, there is NO inbetween! Either rely on a RCD (quite rightly backed up with a type-s), or, get a sub 1ohm value and use that as your back up! Depending on the circumstances, I have done both and will continue to do so. I also maintain that I have never left a TN connection behind unless exporting has not been permitted.

I have no argument against stability, however the value in the regs of 200 ohms is seen to be the absolute maximum value to work to to guarantee that system won't go over 1.6kohms. That value is there for a reason and I'm sure various tests have been conducted to confirm this. I can see how you think every ohm under 200 is a bonus, and in a way, I would have to agree, but in the same way that if you were diagnosed with a terminal illness, every second you lived from that moment on would be a bonus, but at the end of the day the same thing is going to happen!

What I don't get is this notion that if you achieve a value of 200 ohms or less and it is STABLE, as it most likely will be! The OP is testament to this! That it is still somehow a crap value when in reality it will achieve exactly the same function as a value of 10ohms!

If you're happy to rely on two RCDs (a normal and a type-s) with a value of 200 ohms then I cannot see for the life of me how this would make someone lazy!?!

What makes someone lazy (and dangerous) in my opinion is the idiot that comes along with a complete lack of understanding in how a TT system operates and whacks in a new CU, no type-s in sight and leaves their meter long twig sticking half out of the ground. Myself, WP and anyone else for that matter who sees a TT system like we do isn't lazy, nor are we dangerous, because (contrary to what you might THINK) we do hold a fundamental understanding of how TT systems work and are more than prepared to adapt our working practices inline with the regulations and in line with our understanding of electrical theory to suit each individual set of circumstances.

Edit: I might add also that just because I disagree with some of what you say on this subject, it doesn't mean that I don't respect or value your opinion. I would hope that the same would be true of you.

I think if any one with has read any of the posts between E54, wirepuller and yourself on this subject over the last few months, they would have a better understanding of TT systems now!!lol. I don't have the privelage of working on them....there's not a lot of em round here on these council estates..lol But after reading some of the stuff between you more learnered guys, I have a better understanding of them. This place really is good for expanding your knowledge....and I believe you would of probably helped numerous people on here, without even knowing!!

Keep it coming guys....knowledge is power!!lol

 

[Engineer54]

Edit: I might add also that just because I disagree with some of what you say on this subject, it doesn't mean that I don't respect or value your opinion. I would hope that the same would be true of you.

I don't hold or bare any grudges at all DS, against you or anyone. i like a good argument the same as the next man ...so the answer is YES!!

Don't jump to conclusions about the OP's statement, those steel bars may well be as long or longer than 2 X 5/8'' rods.
Also without taking seasonal readings, it can't be confirmed one way or the other. If they are around a metre, then as sure as eggs are eggs, they are not going to be stable, not from the heat of summer to freezing snow of winter, and you can take that to the bank!!

You would need to be in extraordinary a bad soil/ground conditions to have a stable 200 ohm value, if your using 2 X 5/8'' rods. In such unusual conditions, there is very little you can do, without spending time and money, but i can assure you, that 200 ohms can be substantially reduced if it was needed, and i don't mean by just banging in rod after rod. Using the 200 ohm minimal value, is totally barmy for general terms, end of!!

I'm not going to carry on making my point on this matter, i can't be any clearer than what i have already posted. Your clearly going to try and pick at every last detail going by the above post, and frankly i just can't be arsed at this time. I'll just firmly stand-by with what i've posted, as to people making an effort and those that don't or won't.

 

[Outspoken]

With all due respect to anyone here, regardless of anyone's position on this, a reading of 10Ω/20Ω/30Ω/40Ω is vastly superior to 200Ω, whether it is acceptable or not is a wholly different point, but to state lower values are not better is a statement that has the potential of making you look daft.

In reality I think we all know enough to know that the reading should be substantially lower than the quoted 200Ω values stated by the BGB, and a decent engineer or spark will aim as far as is practical for a sub 1Ω reading, so a lot of the arguments are largely moot here and people are simply talking around in circles.

Oh, and discussions about who does the bigger Jobs or has the most responsibility are rather Juvenile

 

[Engineer54]

Oh, and discussions about who does the bigger Jobs or has the most responsibility are rather Juvenile

True, but sometimes it can be very relevant, depending on what it is being related too!!

I'll leave you to now argue with the disbelievers, i need a break!! lol!!

 

[Outspoken]

True, but sometimes it can be very relevant, depending on what it is being related too!!

True, but my comment was in respect of the conversation on this thread about EE's and RCD's

 

[Deleted member 9648]

With all due respect to anyone here, regardless of anyone's position on this, a reading of 10Ω/20Ω/30Ω/40Ω is vastly superior to 200Ω, whether it is acceptable or not is a wholly different point, but to state lower values are not better is a statement that has the potential of making you look daft.It's not about the value obtained that is really the argument,it's the point that any value exceeding TN values relies on RCD protection.All of the above figures you have quoted rely on RCDs for earth fault protection,of course if you compare 10/20 ohms to 200 ohms it would appear the former is 'vastly superior' as you put it. But in practice in the event of an earth fault on a system with RCD's there will be no difference in disconnection time,suddenly 10/20 ohms doesnt look 'vastly superior' after all.

In reality I think we all know enough to know that the reading should be substantially lower than the quoted 200Ω values stated by the BGB, and a decent engineer or spark will aim as far as is practical for a sub 1Ω reading, so a lot of the arguments are largely moot here and people are simply talking around in circles. I do come across quite a few TT systems,as previously stated mostly small,up to single dwellings or farm outbuildings etc,and I cant ever remember coming across a sub 1 ohm value. It is an indisputable fact in the south east UK where I work that nearly all TT's of the type I describe are not built/designed around TN sub 1 ohm values ,but values which rely on RCD protection.I have no doubt whatsoever that DS,who also operates in this neck of the woods ,would confirm what I have stated.

Oh, and discussions about who does the bigger Jobs or has the most responsibility are rather Juvenile

.............

 

[D Skelton]

but to state lower values are not better is a statement that has the potential of making you look daft.

How so? They both achieve exactly the same thing!

What makes people look daft to me is when they say a stable 10/20/30/40ohms is better than a stable 200ohms. Your 40ohms is just as useless as 200 of them!!!

 

[1Justin]

- Phew..Thanks to all.

OP - now with just a little more insight.

I emerge relatively pleased that I put 2 years inspection in his EIC. I may also invite myself back in the winter to check it again.

As there are some opinions here, would you do more (ie go to install new electrode) - Probably at your own expense? (Yes/No).
1960's house, TT in a village on sandy soil, 2 young children, 30mA RCD and PV on separate 100mA RCD, 198 Ohm Rs, Earth electrode is steel and somewhat rusty, no change in Rs (to nearest 1 ohm) since Autumn 2010.

Rgds

1Justin.

 

[Engineer54]

- Phew..Thanks to all.

OP - now with just a little more insight.

I emerge relatively pleased that I put 2 years inspection in his EIC. I may also invite myself back in the winter to check it again.

As there are some opinions here, would you do more (ie go to install new electrode) - Probably at your own expense? (Yes/No).
1960's house, TT in a village on sandy soil, 2 young children, 30mA RCD and PV on separate 100mA RCD, 198 Ohm Rs, Earth electrode is steel and somewhat rusty, no change in Rs (to nearest 1 ohm) since Autumn 2010.

Rgds

1Justin.

Would i do the work at my expense ...NO!!

But you tell us, ...What would you do if it were your house, and your two young children??

What do you mean by Rs, ...Zs?? If so, then your stability can be accounted for, by any main bonding connections and possibly your Ra could be a lot higher than the 198 ohms you have stated!!

 

[Engineer54]

Outspoken, perhaps you can see what i mean now?? lol!!

 

[Rockingit]

I normally keep out of the great rod debate, but DS makes a very good point which I've yet to see anyone give a direct answer to.... if anywhere between 200 ohms and TN ohms requires additional RCD protection, then it is largely irrelevant what that number is. Its a bit like trying to say that getting caught speeding at 100mph is less illegal than getting caught at 120mph.

 

[Deleted member 9648]

I normally keep out of the great rod debate, but DS makes a very good point which I've yet to see anyone give a direct answer to.... if anywhere between 200 ohms and TN ohms requires additional RCD protection, then it is largely irrelevant what that number is. Its a bit like trying to say that getting caught speeding at 100mph is less illegal than getting caught at 120mph.

That is the issue in essence....how is accepting Ra's of 10-15 ohms and not accepting 100-200 logical when in the next breath you are scorning reliance on RCD's?

Perfect analogy.

 

[Deleted member 9648]

- Phew..Thanks to all.

OP - now with just a little more insight.

I emerge relatively pleased that I put 2 years inspection in his EIC. I may also invite myself back in the winter to check it again.

As there are some opinions here, would you do more (ie go to install new electrode) - Probably at your own expense? (Yes/No).
1960's house, TT in a village on sandy soil, 2 young children, 30mA RCD and PV on separate 100mA RCD, 198 Ohm Rs, Earth electrode is steel and somewhat rusty, no change in Rs (to nearest 1 ohm) since Autumn 2010.

Rgds

1Justin.

No. It complies with the regs.If you go down the route of adding more rods how far do you go if it's not coming down to TN values,? if (say) 3 rods gets it to 15 ohms then you are no better off than you were before, so you have to keep going or you've wasted your time.
But I would advise the client of the safety advantages of a 100ma S type upstream of the 30ma on the domestic DB.

 

[GLENNSPARK]

No. It complies with the regs.If you go down the route of adding more rods how far do you go if it's not coming down to TN values,? if (say) 3 rods gets it to 15 ohms then you are no better off than you were before, so you have to keep going or you've wasted your time.
But I would advise the client of the safety advantages of a 100ma S type upstream of the 30ma on the domestic DB.

then the way forward (after your satisfied the 15 ohms will remain stable) would be to site another rod/s nearby...and link it all up....

 

[D Skelton]

then the way forward (after your satisfied the 15 ohms will remain stable) would be to site another rod/s nearby...and link it all up....

And then before you know it you've whacked in 20 rods and you're still not under an ohm. Hmm, what then?

 

[Engineer54]

And then before you know it you've whacked in 20 rods and you're still not under an ohm. Hmm, what then?

Only to those that know no different!!