Earth Rod - Advice please!

[Kaydee]

Hi, I am not an electrician, but need some advice from one, if you wouldn't mind helping, please?
We've just paid £3,500.00 to have a 3-bed semi completely rewired and are told the job is now finished. (We paid half up front, they now want the other half).
Outside the front of the property, they've installed what they've told us is an 'earth rod'. There's a long piece of thick, black, plastic tubing, leading to a unit that is fixed to the ground.
It comes almost onto the driveway, right in front of an attractive bush to the side of the front door and looks really unsightly.
We questioned them about it and were told it was 'regulation' that it had to be installed that way, a metre from the house, in a straight line.
I haven't seen anything like this in front of any other property, including ones that have been recently rewired, but want to check my facts before challenging them on this.
Is this normal? Can it/should it be buried underground?

 

[davesparks]

PME is a major cause of elevated 50 - 100 - 150 Hz magnetic fields in the UK. The multiple Earthing should be good - but why was it done. It was primarily done due to failures in the 1970s and 1980s (and later!) of early three-phase el-cheapo 3 core XPLE cable that used the armouring for Neutral/Earth. Unfortuntely when water gets into those it eats through the poorly plated armouring and bothe Neutral and Earth are lost.

50Hz I can almost possibly believe, but where do you get the 100 and 150 from?
If it was done as a reaction to failures in the 1970's and 80's then why does it feature in the 1955 wiring regulations?
Can you specify exactly what type of cable this was and roughly when it was installed? I wasn't aware that a metal which is so readily 'eaten' by water has ever been used for a CNE conductor, what was it?

 

[alasdairp]

Hi - sorry, I probably misread your post. I thought you were comparing the Earth's magnetic field to that generated by AC in an earthing rod. Can I ask what is / how is it measured the "UK average 0.04 micro Tesla" ? Thanks.

National Grid and the ENA now say 0.05 uT. The level is from hundred of studies (many, many, thousands of measurements including data-logging) across the UK over the past 40 years. See that National Grid / ENA info at:
Field levels and exposures | EMFs.info - http://www.emfs.info/sources/levels/
If people are interested we should start another discussion thread. I can point people at loads of evidence if they are interested. Actually, measuring magnetic fields with and without a single load like a fan heater or kettle, is the quickest way to determine if a ring circuit is in good health - MUCH quicker (almost instant) as a 'look-see' than measuring the detailed circuit parameters.
There are many AC magnetic field meters on the market.

 

[DPG]

National Grid and the ENA now say 0.05 uT. The level is from hundred of studies (many, many, thousands of measurements including data-logging) across the UK over the past 40 years. See that National Grid / ENA info at:
Field levels and exposures | EMFs.info - http://www.emfs.info/sources/levels/
If people are interested we should start another discussion thread. I can point people at loads of evidence if they are interested. Actually, measuring magnetic fields with and without a single load like a fan heater or kettle, is the quickest way to determine if a ring circuit is in good health - MUCH quicker (almost instant) as a 'look-see' than measuring the detailed circuit parameters.
There are many AC magnetic field meters on the market.

I'm not convinced this is going to prove that the Zs of the circuit is sufficient to ensure operation of the OCPD,

 

[alasdairp]

Hi - sorry, I probably misread your post. I thought you were comparing the Earth's magnetic field to that generated by AC in an earthing rod. Can I ask what is / how is it measured the "UK average 0.04 micro Tesla" ? Thanks.

National Grid and the ENA now say 0.05 uT. The level is from hundred of studies (many, many, thousands of measurements including data-logging) across the UK over the past 40 years. See that National Grid / ENA info at:
Field levels and exposures | EMFs.info - http://www.emfs.info/sources/levels/
If people are interested we should start another discussion thread. I can point people at loads of evidence if they are interested. Actually, measuring magnetic fields with and without a single load like a fan heater or kettle, is the quickest way to determine if a ring circuit is in good health - MUCH quicker (almost instant) as a 'look-see' than measuring the detailed circuit parameters.
There are many AC magnetic field meters on the market.

50Hz I can almost possibly believe, but where do you get the 100 and 150 from?
If it was done as a reaction to failures in the 1970's and 80's then why does it feature in the 1955 wiring regulations?
Can you specify exactly what type of cable this was and roughly when it was installed? I wasn't aware that a metal which is so readily 'eaten' by water has ever been used for a CNE conductor, what was it?

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.

 

[Midwest]

I can see conspiracy theories abound on this for many more posts & threads in the future

 

[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 ?