Max Ze for TT system

[Engineer54]

It basically comes down to, ....those that will make an effort to install a ''Working'' TT system or those that have no intention of making any effort and taking that 200 ohm value as a lame excuse to do virtually nothing, because they are in there mind, complying. Of course stability would then indeed have to be overrated wouldn't it, regardless of what any of the multitude of papers written on the subject have to say!!

 

[Engineer54]

Can you get 30mA time delayed RCDs?:devilish:

Yes, more than a few well know manufactures provide them...

 

[Deleted member 9648]

It basically comes down to, ....those that will make an effort to install a ''Working'' TT system or those that have no intention of making any effort and taking that 200 ohm value as a lame excuse to do virtually nothing, because they are in there mind, complying. Of course stability would then indeed have to be overrated wouldn't it, regardless of what any of the multitude of papers written on the subject have to say!!

In the highly unlikely event that I ever again have to install a TT to either a commercial or large residential then yes...I would be making an effort to get a TN value.I say highly unlikely because these days TNCS is almost always available in my area. I still do a lot of TT's,but small scale. The most recent being a small unit supplying a few sockets for small fairground/entertainment use on a playing field,and temporary civil engineering supplies on a sea front site.For those I believe the standard UK sub 200 ohm and RCD arrangement is perfectly adequate,and if it was 150 ohms at the time of installation and when I came back for a 3 month re-test it had risen to 160 ohms it wouldnt worry me in the least.
That said as Skelton stated in a previous post....I regularly go back to TT's I have installed over the years and cant ever remember initial readings varying to any great degree.

 

[Engineer54]

In the highly unlikely event that I ever again have to install a TT to either a commercial or large residential then yes...I would be making an effort to get a TN value.I say highly unlikely because these days TNCS is almost always available in my area. I still do a lot of TT's,but small scale. The most recent being a small unit supplying a few sockets for small fairground/entertainment use on a playing field,and temporary civil engineering supplies on a sea front site.For those I believe the standard UK sub 200 ohm and RCD arrangement is perfectly adequate,and if it was 150 ohms at the time of installation and when I came back for a 3 month re-test it had risen to 160 ohms it wouldnt worry me in the least.
That said as Skelton stated in a previous post....I regularly go back to TT's I have installed over the years and cant ever remember initial readings varying to any great degree.

You have often stated in your posts, that soil/ground conditions in you're particular area are not good, and that's fair enough as far as i'm concerned. But you can't go making the same assumptions to those posters that work in and around pretty decent areas, where in some cases i personally know near TN values CAN be attained, in some cases pretty easily too.

Personally i would endeavour to initially treat domestics as i would any other type of installation, only backing off, to let's call it the fall back position, when costs are going to be a major factor.

 

[sparks1234]

We know what it say's, but i'll guarantee you, that virtually every poster that comes on this and other forums, that isn't knowledgeable on TT systems, take that figure in BS 7671 as being the stated maximum and that's what they inevitably will work too!! ...And why i always Poo it off!! lol!!

The whole section on TT earthing needs a thorough sorting out and a bit more guidance wouldn't go amiss either!!

I'm going home (Cyprus) for Xmas this year, and while home, i'll be checking my own TT system. Earlier this year (early summer) it was around 0.93 ohms which has been steadily dropping year on year from around 4'ish ohms.

Here on site, our earth fields were tested middle of last month and recorded 0.17 ohms and 0.21 on the other. The highest value recorded this year was 0.28 and 0.30 respectively, which corresponds to similar test results conducted last year.

It's surprising what can be achieved when you know what you're doing!! lol!!

So that's what you do with your christmas

think I'll eat turkey and have a good time, knickers to the earth rods

 

[Engineer54]

I think i can find the time to check my TT system Ra value, it's not as if i'm not home just for the one day like!! I'm sure i'm going to find a lot more maintenance issues that need attending too while home. It's always the same when a house is left unattended for long periods of time!! lol!!

Besides, 15 or so minutes to check the safety of an earthing system, isn't the end of the world, well not mine anyway!!

 

[D Skelton]

I can just imagine you Eng, the missus inside calling you outside "Sweetheart! The turkey needs carving!", "Just a minute dear, it's of upmost importance that I check the condition of my rod first!", "But you did that yesterday dear, and the day before... And the day before that as well?", "Erm, err, no dear, I don't think I did *chuckle chuckle*, what are you like hey dear? *whilst muttering to yourself>>>* crazy old bat, thinks I'm going senile! Tut".

 

[Guest 004]

15 mins to check your rods? Why?

I suppose you want your ra values.

You would have checked them before? Why don't you just plug in a metre into a socket and loop it, then do your rcd tests?

2 mins max. Which leaves you 13 mins dig your metre out.

 

[Guest 004]

Insanity: doing the same thing over and over again and expecting different results.
Albert Einstein

 

[wersolaruk]

Engineer54 a "working" earth what the hell is that? Us electricians call it a stable or un stable earth.

 

[sparks1234]

Engineer54 a "working" earth what the hell is that? Us electricians call it a stable or un stable earth.

He likes a laugh doesn't he
i think that's the difference between an engineer and a sparky though, we live in the real world.

 

[i=p/u]

E54 is a qualified part p,pat tester .. Ho ho ho

 

[Clive P]

Hi,

How do you PAT test an Earth Rod? Is it done in increments from 0 to 200 ohms?

Regards.

 

[i=p/u]

Just a visual will do

 

[MDJ]

You will all regret your comments when he is here later lol

 

[D Skelton]

You will all regret your comments when he is here later lol

I think Eng will regret telling us all that the first thing he does on Christmas morning, even prior to opening his stocking from Santa, is to test his earth rod!

 

[Silly Sausage]

He must have very long legs.
It's what he gets every year, a bundle of 2.4m rods in his stocking.

And instead of a Christmas card, he gets a brand new Cal Cert for his Earth Tester.

 

[SPARTYKUS]

I'm waiting for the thunder clap when the time zone in China or Cyprus comes round.....

- - - Updated - - -

Popcorn ready, blanket on knees.

ok go.

 

[spark 68]

Nah! E54s bark is worse than his bite lol, he is just a big ol' ----- cat lol

He won't be bothered about us p*** taking about his "rod measuring activities" ooer missus lol , whether over Christmas or not.

If you really want to make him bite, try telling him a 200 ohm rod is just as good as a sub 20 or less ohms one lol, better still a ''twig' is just as good as well

 

[Silly Sausage]

Where's wirepuller?

or is that chainpuller?

 

[Guest 004]

To measure an earth rod, you need a 3 or 4 lead tester, depending on the make, one lead is attached to the rod, then the other leads are attached to twigs, er sorry probes which are then placed in the ground at given distances from the rod. Any connection's to installation would need to be disconnected.

 

[spark 68]

We can use an EFLI tester, this gives enough accuracy on the side of caution to measure this.

Granted you may need a proper tester for the installations of generators and the like on some larger industrial sites, you can also use stakeless testers now as well.

 

[Guest 004]

Indeed, quite a few methods to measure, and if the rod has already been tested, then a loop at a socket with a calculation is fine.

 

[Engineer54]

15 mins to check your rods? Why?

I suppose you want your ra values.

You would have checked them before? Why don't you just plug in a metre into a socket and loop it, then do your rcd tests?

2 mins max. Which leaves you 13 mins dig your metre out.


Maybe in you're world everything is prepared and all you do is push the button, doesn't quite work like that in the real world though!!


Insanity: doing the same thing over and over again and expecting different results.
Albert Einstein


Which all goes to show, just how little you know about TT systems!!

To measure an earth rod, you need a 3 or 4 lead tester, depending on the make, one lead is attached to the rod, then the other leads are attached to twigs, er sorry probes which are then placed in the ground at given distances from the rod. Any connection's to installation would need to be disconnected. ​

And is exactly the method i use as i have an open field to the back of my property, so i have the distance to obtain accurate measurements... I'd like to see you hook that little lot up and conduct the tests in 3 mins!! ...lol!!

Engineer54 a "working" earth what the hell is that? Us electricians call it a stable or un stable earth.

Stability is an important factor, but a working TT system (earth) is one that is as near TN values as you can possibly get, and not one, that you'd probably be happy with, by following the BGB!!

I think most Engineers, especially those that are site based HAVE to live in the real world, and probably more so than the average jobbing electrician. Responsibility comes with a price when you get it Wrong, as even some small errors, can end up costing the client or the contractor (or both)some pretty serious money!!

 

[Guest 004]

I think a serious waste of money is trying to acheive TN values on a TT system.

 

[D Skelton]

It is often the opposite though. What would you do if you had a 200A supply or more?

 

[spark 68]

I think a serious waste of money is trying to acheive TN values on a TT system.

Depends entirely on the site, it may be well be cost effective and desirable on large projects to achieve TN values from a TT system, the cost savings of not needing RCDs alone would make it worth while (not talking about final circuits here), using TNC-S and PMEing such a large project may also have massive cost implications, and may not be an option based on cost grounds, this could be down to the size of the bonding conductors, or it may simply be not allowed at all for one reason or another, likewise TN-S may also have huge costs attached.

This is where E54 is perfectly correct, but I also tend to fit in the other camp where domestic is concerned, that is I try to get it as low as is reasonably practicable, but see little point in over engineering it past say two rods driven deeply, if I can get it reasonably low (below tens of ohms) and stable I am usually happy.

 

[Guest 004]

Which all goes to show, just how little you know about TT systems!!

I have worked extensively on TT systems and tested them, both in the UK (LUL) and South East Asia

 

[D Skelton]

Very confused as to why Eng isn't biting anymore?! Has the wriggler stopped wriggling? Is he just chilling with the rest of the fish?

 

[pepparz]

hes probably had enough, gone insane and been sectioned.

 

[Engineer54]

I have worked extensively on TT systems and tested them, both in the UK (LUL) and South East Asia
[/COLOR]

You could have fooled me with the statements you come out with above!!!

 

[Engineer54]

Very confused as to why Eng isn't biting anymore?! Has the wriggler stopped wriggling? Is he just chilling with the rest of the fish?

Can't be asrsed basically, too busy clearing up my desk and looking forward to my vacation!! lol!!

 

[Engineer54]

hes probably had enough, gone insane and been sectioned.

Can't leave it alone can you!! One thing i can assre you of, and that's, that you'll be sanctioned long before it's my turn!!

 

[Guest 004]

Can't be asrsed basically, too busy clearing up my desk and looking forward to my vacation!! lol!!

Still at your desk, cleared mine last Friday , and not going back for 6 weeks. Now enjoying glorious sunshine in my TT abode in SE Asia.

Sorry couldn't resist.

 

[sparks1234]

Can't be asrsed basically, too busy clearing up my desk and looking forward to my vacation!! lol!!

Ahha, so there we have it E54 is a paper shuffler and not in the real world….LOL

 

[Engineer54]

Still at your desk, cleared mine last Friday , and not going back for 6 weeks. Now enjoying glorious sunshine in my TT abode in SE Asia.

Sorry couldn't resist.

And i hope you enjoy youre 6 weeks off too...

 

[Engineer54]

Ahha, so there we have it E54 is a paper shuffler and not in the real world….LOL

It comes with the territory i'm afraid, but it's never stopped me getting my hands dirty, so i don't have to make stuff up either!! lol!! Think the new word for it these days is, being able to multi-task!!

 

[Guest 004]

And i hope you enjoy youre 6 weeks off too...

Thank you very much sir, hope you enjoy yours as well.