TN-C-S or TT?

[Edd]

Well that's not completely true at all. So what do you think happens when a TN-S supply is converted to TNC-S/PME??
They will only use crimped connections when a joint is replaced, they certainly aren't going to replace every joint on the distribution supply run before converting a households service head. It maybe several years before a converted distribution cable is fully PME'd, and is more likely than not, supplying both TN-S and TNC-S during that period.

By the way, there is nothing wrong at all, with soldered joint connections, they have been around long, long before crimped connections, they are as sound as any crimp connection too. There are very few circumstances where soldered terminations are not advised or permitted...

Funny thing was I was also told that Only crimped distributions systems would be converted to PME. From EEB (as you know), was quite a few years ago though!!
Also every 3rd or 4th pole as you said in a previous post to be staked. If they are working on an area and having to fit all these stakes at the poles, It would make sence to sort the joints out at the same time. Saying that I have seen many soldered overhead PME systems, so maybe they have changed their rules or its been converted DIY.

Edit,, I think it was the old U bolt type joints they were more on about

 

[Engineer54]

Funny thing was I was also told that Only crimped distributions systems would be converted to PME. From EEB (as you know), was quite a few years ago though!!
Also every 3rd or 4th pole as you said in a previous post to be staked. If they are working on an area and having to fit all these stakes at the poles, It would make sence to sort the joints out at the same time. Saying that I have seen many soldered overhead PME systems, so maybe they have changed their rules or its been converted DIY.

Edit,, I think it was the old U bolt type joints they were more on about

Can't say i've seen a soldered joint on an overhead system. All the joint's connections i've seen on such installations have been via multiple clamp connectors. On some of the very old overheads it was by means of splicing (a lost art form) and clamps.

Sorry if it wasn't too clear, but I was talking about underground cables (PILC and the like) that are being converted from TN-S to TNC-S/PME Where every joint will most certainly be soldered connections unless it's been repaired/replaced in recent years. Now converting every joint at the same time in those circumstances, would be both time consuming, very costly and be an intolerable inconvenience for those customers connected to that distribution line...

 

[Geordie Spark]

Well that's not completely true at all. So what do you think happens when a TN-S supply is converted to TNC-S/PME??
They will only use crimped connections when a joint is replaced, they certainly aren't going to replace every joint on the distribution supply run before converting a households service head. It maybe several years before a converted distribution cable is fully PME'd, and is more likely than not, supplying both TN-S and TNC-S during that period.

By the way, there is nothing wrong at all, with soldered joint connections, they have been around long, long before crimped connections, they are as sound as any crimp connection too. There are very few circumstances where soldered terminations are not advised or permitted...

Thank you !!!

 

[Edd]

My typo above,, I did try edit it... One too many beers I think! Yep Beer and the Electricians forum makes for intresting reading

 

[SPARTYKUS]

Edd tried to Ed it it

 

[somersetsparks]

The dno will usually replace the main distribution cable under a street and rejoin all the other cables to properties etc. to it and leave them as TNS, You can usually tell this has been done as the Ze readings will be very low!
If you then have the cut-out replaced, they will have no problems connecting it as a PME supply, In fact if you ring in our area, they will tell you whether you are allowed to connect it PME, especially if the earth clamp is missing from a TNS cable.
In our area, there is virtually no 'true' underground TNS systems left

 

[Engineer54]

The dno will usually replace the main distribution cable under a street and rejoin all the other cables to properties etc. to it and leave them as TNS, You can usually tell this has been done as the Ze readings will be very low!
If you then have the cut-out replaced, they will have no problems connecting it as a PME supply, In fact if you ring in our area, they will tell you whether you are allowed to connect it PME, especially if the earth clamp is missing from a TNS cable.
In our area, there is virtually no 'true' underground TNS systems left

Your living in cloud cuckoo land if you think the DNO is going to replace a serviceable cable that still has many years of life in it, in TNC-S form. Apart from that, do you have any idea how much it would cost, to say dig-up/trench just a half kilometre of residential road lay a new cable and then joint for every house/dwelling, ...let alone how long it will take and the inconvenience to it's customers from having daily power outages while the work continues?? I can assure you, they wouldn't even think about such work, unless it was absolutely 200% necessary.... and even then they will be looking for other ways to get past the problem... lol!!!

Many under ground cables are in the process of being PME'd, which means that the distribution cable in question will in all likelihood be supplying both TN-S and TNC-S. Which is another reason why DIY N-E connections at a service head can be extremely dangerous. Only the DNO will know what section(s) of that distribution cable has been converted to TNC-S.

 

[somersetsparks]

Your living in cloud cuckoo land if you think the DNO is going to replace a serviceable cable that still has many years of life in it, in TNC-S form. Apart from that, do you have any idea how much it would cost, to say dig-up/trench just a half kilometre of residential road lay a new cable and then joint for every house/dwelling, ...let alone how long it will take and the inconvenience to it's customers from having daily power outages while the work continues?? I can assure you, they wouldn't even think about such work, unless it was absolutely 200% necessary.... and even then they will be looking for other ways to get past the problem... lol!!!

Many under ground cables are in the process of being PME'd, which means that the distribution cable in question will in all likelihood be supplying both TN-S and TNC-S. Which is another reason why DIY N-E connections at a service head can be extremely dangerous. Only the DNO will know what section(s) of that distribution cable has been converted to TNC-S.

No I'm not living in cloud cuckoo land, and no I'm not sure of the cost but.... I do work for a DNO, I'm not gonna say which one, and I can tell you in our area, a lot of the main distribution cables have been replaced and yes it was a hell of a lot of work, on the other hand you are correct, the other remaining TNS cables have all been PME'd, so in our area PME is 99.9% available.
Please stop being so patronising.

 

[Engineer54]

Patronising i'm not!! You must work for the only DNO in the country that strips out complete local network distribution cables and replaces with new, along with all the branch lines joints off to the householders service cut-out. And if they Do, ....not to the point, where 99.9% of the area's LV network distribution cables have been replaced, or have been fully PME'd....

 

[Jimmy Boy]

That's basically a very good standard to have, it's very much the same in most Western European countries too. Shame they don't insist on the same in the UK.

To EN54 and Guitarists posts I also considered doing this on my overhead tncs/pme but would like your comments on the potential danger that may arise under broken neutral scenario, as i understand it as rare as it is, all metal will rise to 230v, now if i have the 'best' or lowest path of resistance to a secondary earth rod in my block of dwellings isn't all or the majority of the fault going to head my way ?

J

 

[somersetsparks]

Patronising i'm not!! You must work for the only DNO in the country that strips out complete local network distribution cables and replaces with new, along with all the branch lines joints off to the householders service cut-out. And if they Do, ....not to the point, where 99.9% of the area's LV network distribution cables have been replaced, or have been fully PME'd....

Patronising you are i'm afraid, although you have a huge knowledge, the way you deliver it is very argumentitive and egotistical IMO
Well in built up areas, PME is 99.9% available, In fact in the large town I live in, there is barely a property were it isnt available, millions have been spent in the last 10 years doing service renewals, there are still paper leads around but almost all have been PME'd. There was a huge program to upgrade the overloaded network which is now essentially complete.

 

[Engineer54]

Patronising you are i'm afraid, although you have a huge knowledge, the way you deliver it is very argumentitive and egotistical IMO
Well in built up areas, PME is 99.9% available, In fact in the large town I live in, there is barely a property were it isnt available, millions have been spent in the last 10 years doing service renewals, there are still paper leads around but almost all have been PME'd. There was a huge program to upgrade the overloaded network which is now essentially complete.

You can read into, what and how i deliver my posts anyway you like, i have no control at all on that score!!

But i will say it again, your DNO must be the ONLY one in the country digging up street by street to replace/renew existing PILC cables, in order to have PME distribution...

I wonder if anyone else here, knows of any such DNO programme that is going on, or has been completed in there neck of the woods??

 

[somersetsparks]

You can read into, what and how i deliver my posts anyway you like, i have no control at all on that score!!

But i will say it again, your DNO must be the ONLY one in the country digging up street by street to replace/renew existing PILC cables, in order to have PME distribution...

I wonder if anyone else here, knows of any such DNO programme that is going on, or has been completed in there neck of the woods??

Well I only no what goes on in our area, I'm guessing you have checked with all the other DNO's in the country, so I won't bother to argue the fact.

 

[Engineer54]

Well I only no what goes on in our area, I'm guessing you have checked with all the other DNO's in the country, so I won't bother to argue the fact.

You may think i'm having a pop at you, but i'm not!!

What i do know, is that what your describing makes for economic nonsense. Even the cost of PME'ing every joint on an existing street distribution cable, would be prohibitive, against a zero monetary return, to what are now all private companies, that has shareholders. All they will want to see, is their shares increase in value and dividends increase.... I can understand PME'ing overhead LV distribution lines, as they are relatively cheap to convert, compared to underground street network distribution systems.

If as you say, this has been done by your area DNO, then the residents and businesses should consider themselves very lucky indeed....

 

[somersetsparks]

You may think i'm having a pop at you, but i'm not!!

What i do know, is that what your describing makes for economic nonsense. Even the cost of PME'ing every joint on an existing street distribution cable, would be prohibitive, against a zero monetary return, to what are now all private companies, that has shareholders. All they will want to see, is their shares increase in value and dividends increase.... I can understand PME'ing overhead LV distribution lines, as they are relatively cheap to convert, compared to underground street network distribution systems.

If as you say, this has been done by your area DNO, then the residents and businesses should consider themselves very lucky indeed....

You are right, they won't just decide to rip out a whole towns PILC cables but after numerous faults in particular streets etc. and the need for extra capacity for the fast growing town (doubled in last 40 years), I suppose it became necessary to do? Not all streets are done obviously and even where they are any branches etc. have usually been left. I can only speak for the town I work in and its immediate area and I'm certainly not in a management role, more of a grunt on the ground, always found it fascinating to watch the jointers joint to PILC though, such a skill.