Earth Rod - Advice please!

[Midwest]

Neutral to avoid the problem. I have come across hundreds of examples in my working life.

Shocking spelling lets you down.

 

[freddo]

This reminds me of a discussion a while back in another forum about ring finals and magnetic fields...

 

[davesparks]

The armouring is tinned steel. The tinning was often poor, the plastic outer gets damaged, water gets in and the steel rusts through. All the RECs/DNOs know this is a significant problem with ealry XPLE 3 core three phase U/G cables. Modern ones are better, but many now use 4-core cables with a separate Neutral to avoid the problem. I have come across hundreds of examples in my workig life.

Im struggling to find any reference to this cable at the moment, it doesn't appear in any of ukpn's documents on legacy equipment or jointing manuals as far a separate I can see.
Does this cable have a unique name or identifying acronym I can search for?

Also do you have any answer to my other questions?

 

[alasdairp]

Im struggling to find any reference to this cable at the moment, it doesn't appear in any of ukpn's documents on legacy equipment or jointing manuals as far a separate I can see.
Does this cable have a unique name or identifying acronym I can search for?

Also do you have any answer to my other questions?

XPLE stands for Cross-Linked Polyethylene which is now commonly used for SWA cables.
PVC SWA vs XPLE SWA? - http://www.electriciansforums.co.uk/threads/pvc-swa-vs-xple-swa.53841/
Early versions were not very reliable as they were susceptible to mechanical damage and water got in to the armouring. The steel was not stainless nor adequately plated and the water causes it to rust through, removing both the Neutral and Earth connections as the 3-core cable does not have a separate Neutral conductor.

The higher harmonic frequencies (not just 100 and 150 Hz) become a higher % of the total current when the three-phase currents are unbalanced and there is no Neutral. In fact the current usually becomes very noisey with lots of semi-random noise as well. That is also partly due to the large number of switched-mode power supplies now used in most consumer equipment instead of transformers.

p.s. I like your photo - I have been a "landy" man since 1971...

 

[davesparks]

XPLE stands for Cross-Linked Polyethylene which is now commonly used for SWA cables.
PVC SWA vs XPLE SWA? - http://www.electriciansforums.co.uk/threads/pvc-swa-vs-xple-swa.53841/
Early versions were not very reliable as they were susceptible to mechanical damage and water got in to the armouring. The steel was not stainless nor adequately plated and the water causes it to rust through, removing both the Neutral and Earth connections as the 3-core cable does not have a separate Neutral conductor.

The higher harmonic frequencies (not just 100 and 150 Hz) become a higher % of the total current when the three-phase currents are unbalanced and there is no Neutral. In fact the current usually becomes very noisey with lots of semi-random noise as well. That is also partly due to the large number of switched-mode power supplies now used in most consumer equipment instead of transformers.

p.s. I like your photo - I have been a "landy" man since 1971...

I am well aware of what XLPE stands for (not XPLE) and it's applications in modern cables. What I'm asking for is some sort of reference to the actual type of cable you are describing as I can't find any reference to it, or the problems, in any of the documents I have from a DNO regarding problems with legacy equipment or jointing instructions for legacy cables.

Harmonics in the neutral conductor are a problem which is well known about yes, particularly third order harmonics which don't cancel out in the neutral conductor. SMPS and other electronics are a cause of this.
But you said that PME is a cause of 100 and 150Hz magnetic fields, the harmonics you are describing are not unique to PME and don't explain these elevated magnetic fields you describe. How is PME causing this?

And my third question was regarding the timeline. You stated that PME was done in the 70's and 80's to failures of early 3core XLPE cables, yet multiple earthing has been detailed in regulations and reference books since the 50's. Also if it was 3core cable then it would have been installed as PME from the outset and so to say that PME had been later applied to the failing cables just doesn't make sense.

I am open minded on the subject and and happy to be proved wrong in my current understanding and belief, but I will do my own research to find before changing my mind. At the moment there are too many apparent holes in your statements.

I have no problem with the idea that magnetic fields could have an effect on living tissue and organisms, but I have yet to see any believable way that this could extend to causing specific cancers in young humans.

 

[Midwest]

I can see this continuing for a while. I have no idea what is being talked about, but I do totally agree with your last paragraph davesparks.

 

[seltechpc]

This topic of electromagnetic waves causing illness, such as cancer, has been going on for at least 50 years to my personal knowledge. It seems to get a burst of popularity every time a new generation of people suddenly find out about it and think they have stumbled on a major issue.
After my student apprenticeship in the CEGB (to become National Grid in 1990) I not only worked in live 400/275kV substations but my office was also surrounded by overhead droppers just outside the window 5 days a week for more than 30 years and after that probably at least twice a week for another 20. I do not think it has caused me any illness that I know of, nor many of my hundreds of colleagues over the years caught cancer in any greater ratio than the general public.

These small meters that measure magnetic levels are a joke. A contractor arrived at a large 400kV substation to do a small job, his company had given him one of these devices and was told to not work in any area where the reading was in the red .The reading was in the red permanently after he came in the main gate. The level in a substation is many 1000's times that which would be found anywhere else in the country and if there was to be any long term effect on human beings then it would have been picked up by the statistics of people working in substations.

The CEGB and latterly the National Grid clearly have an interest in the safety of people who work in the substations. Many studies have been carried out by experts in their field but no proof has ever been published to prove magnetic fields cause human beings problems. I believe it to be wrong to keep pushing the fact that it is harmful as it causes people to worry about their loved ones safety needlessly.

 

[telectrix]

you are wrong. these magnetic fields are incredibly dangerous to humankind. alien spacecraft home in on them and seek to take over the planet. ain't you seen "war of the worlds", "independence day", "day of the triffids"?

 

[seltechpc]

Wow Tel, we never thought of that at the time, I guess we had a lucky escape

 

[Dave OCD]

I am well aware of what XLPE stands for (not XPLE) and it's applications in modern cables. What I'm asking for is some sort of reference to the actual type of cable you are describing as I can't find any reference to it, or the problems, in any of the documents I have from a DNO regarding problems with legacy equipment or jointing instructions for legacy cables.

Harmonics in the neutral conductor are a problem which is well known about yes, particularly third order harmonics which don't cancel out in the neutral conductor. SMPS and other electronics are a cause of this.
But you said that PME is a cause of 100 and 150Hz magnetic fields, the harmonics you are describing are not unique to PME and don't explain these elevated magnetic fields you describe. How is PME causing this?

And my third question was regarding the timeline. You stated that PME was done in the 70's and 80's to failures of early 3core XLPE cables, yet multiple earthing has been detailed in regulations and reference books since the 50's. Also if it was 3core cable then it would have been installed as PME from the outset and so to say that PME had been later applied to the failing cables just doesn't make sense.

I am open minded on the subject and and happy to be proved wrong in my current understanding and belief, but I will do my own research to find before changing my mind. At the moment there are too many apparent holes in your statements.

I have no problem with the idea that magnetic fields could have an effect on living tissue and organisms, but I have yet to see any believable way that this could extend to causing specific cancers in young humans.

I can't provide any back up info right now Dave but I'd say the problematic network cabling would have been far more likely to be aluminium that caused problems in the 70s and 80s ?

 

[davesparks]

I can't provide any back up info right now Dave but I'd say the problematic network cabling would have been far more likely to be aluminium that caused problems in the 70s and 80s ?

I would have thought the same, I didn't think steel had ever been used for a live conductor in underground LV mains.
I think there was an aluminium sheathed cable similar in construction to PILC cables used at one point.

 

[freddo]

I didn't think steel had ever been used for a live conductor in underground LV mains.

It would be a rather silly arrangement, not one I've ever seen or heard about.

 

[FatAlan]

Isn't planet earth one dirty great big magnet? Funnily enough they reckon it's in a state of flux at the moment and it's about to swap poles!
What I like to know is... if the earth flips poles does that mean all the penguins will have to swim north?

 

[telectrix]

Isn't planet earth one dirty great big magnet? Funnily enough they reckon it's in a state of flux at the moment and it's about to swap poles!
What I like to know is... if the earth flips poles does that mean all the penguins will have to swim north?

they won't go till all the polar bears have gone south.

 

[Jurassic Sparks]

I am slightly surprised that near Gloucester city centre the electricity distribution network is not PME (T-N-C-S) with the Earth connection being supplied with the network supply to the house. I wonder if there was a problem with that and the Earth Rod was a dodgy relatively quick fix to lower Ze rather than getting the DNO in to sort their problem. Check if your neighbours all have Earth Rods. If you need one, they will also need one. If they don't have them, then I would ask for a second opinion. You could check with Western Power Distribution on 0845 601 5972 and ask them if your house should need a separate earth rod. If there is a PME system then you should normally not also have an Earth rod as it can lead to stray currents in the network and elevated magnetic fields in your house.

I live and work in that area
many of the houses I visit are TT systems
I have also seen chumps fitting a BS951 earth clamp onto the old lead sheathed oil filled cables ( unsafe practice) to get an earth rather than fitting an external electrode

 

[Midwest]

Isn't planet earth one dirty great big magnet? Funnily enough they reckon it's in a state of flux at the moment and it's about to swap poles!
QUOTE]

QUOTE]

?

Swapping Poles, is that the immigration plane that flies back Polish Criminals, only for them to arrive back a few weeks later

 

[David M]

My understanding is that the low frequency electromagnetic waves produced from power lines/stations is well below what would be required to cause serious damaging effects to cellular life. In fact much higher frequency electromagnetism is often used to treat certain medical conditions.

 

[FatAlan]

It would mean that Poland would become South Poland and Pete999 would technically be living in Southampton