Earth Rod - Advice please!

[alasdairp]

PME already has an earth rod installed along the distributing main every 40m or less, and at the end of the main. How would an earth rod connected to an installation's MET create a problem that all those other earth rods don't?
Not to mention the bonding of extraneous parts which could be connecting a much bigger earth electrode to the installation.

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. I have found places (commercial installations) where more than 350 amps are flowing though earth, old gas pipes, old water pipes because of this problem. When it happens, without PME, the 3-phases become unblanced and one may get 150 volts and another 350 volts rms. So customers equipment dies - and there are quite a few case studies of this happening - hundreds of homes with damaged equipment. PME tends to hold Neutral fairly well when this happens; some people get a little too high a voltage and some get dim bulbs, etc., that flags a fault without doing much damage.

The problem if you put and Earth rod in and bond it to metal water and gas pipes (ok, older houses with metal supply pipes) then stray current (mostly due to PME!) that has coupled onto those pipes can flow through the bonding and into the ground at your house. It does not matter much if all 3 services enter the house at the same place and are bonded there - but I have visited houses (especially council and ex-ones) where the water and sewage go along the back gardens but the electricity and gas come in at the front. I have measured 37 Amps flowing throug the bonding conductor from back to front of a terraced house (with a child who developed leukaemia) due to this problem - creating enormous magnetic fields (20 microteslas when UK average is 0.04 microtesla) inside the house as the go and return currents are taking completely different routes.

Easy way to tell if there is a problem is (always!) to put a clamp meter around the bonding conductors (in every installation!) and measure the current. It should be zero. If it more than an amp, I believe it should be rectified. Usual way is to insert a piece of insulating pastic pipe in the gas or water pipe wehere it enters the building to break the stray current path.

 

[alasdairp]

PME already has an earth rod installed along the distributing main every 40m or less, and at the end of the main. How would an earth rod connected to an installation's MET create a problem that all those other earth rods don't?
Not to mention the bonding of extraneous parts which could be connecting a much bigger earth electrode to the installation.

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. I have found places (commercial installations) where more than 350 amps are flowing though earth, old gas pipes, old water pipes because of this problem. When it happens, without PME, the 3-phases become unblanced and one may get 150 volts and another 350 volts rms. So customers equipment dies - and there are quite a few case studies of this happening - hundreds of homes with damaged equipment. PME tends to hold Neutral fairly well when this happens; some people get a little too high a voltage and some get dim bulbs, etc., that flags a fault without doing much damage.

The problem if you put and Earth rod in and bond it to metal water and gas pipes (ok, older houses with metal supply pipes) then stray current (mostly due to PME!) that has coupled onto those pipes can flow through the bonding and into the ground at your house. It does not matter much if all 3 services enter the house at the same place and are bonded there - but I have visited houses (especially council and ex-ones) where the water and sewage go along the back gardens but the electricity and gas come in at the front. I have measured 37 Amps flowing throug the bonding conductor from back to front of a terraced house (with a child who developed leukaemia) due to this problem - creating enormous magnetic fields (20 microteslas when UK average is 0.04 microtesla) inside the house as the go and return currents are taking completely different routes.

Easy way to tell if there is a problem is (always!) to put a clamp meter around the bonding conductors (in every installation!) and measure the current. It should be zero. If it more than an amp, I believe it should be rectified. Usual way is to insert a piece of insulating pastic pipe in the gas or water pipe wehere it enters the building to break the stray current path.

 

[HandySparks]

As for tooling to do the job, i'm not sure if spending £400-500 on a jack hammer that's only used periodically is a good investment.

Buy or make an adaptor for your SDS drill (if it has a hammer only setting).

 

[HandySparks]

As for tooling to do the job, i'm not sure if spending £400-500 on a jack hammer that's only used periodically is a good investment.

Buy or make an adaptor for your SDS drill (if it has a hammer only setting).

 

[ppuch1]

Buy or make an adaptor for your SDS drill (if it has a hammer only setting).

I have found atool that does the job for that, but a decent SDS hammer drill to do the job is bigger than most of us have in our tool kit as the norm. It may need 10kg hammer in some types of ground as nothing smaller will sufffice. I would be interested to know from anyone what they have found that fits the bill. I have seen a few recommended tools such as Makita and Bosch or Dewalt like in the attached picture.
http://www.electriciansforums.co.uk/attachments/banging-a-rod-jpg.15634/

 

[Midwest]

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.

Think you'll find that a lot of supplies in town centres are TT. Whilst DNO's seek to upgrade where they can, this can be more problematic in towns where the supply cables are festooned on property walls etc. This is what one DNO engineer told me, one called a TT supplied property in a local town.

You may wish to have a look at the public draft for comment of the 18th edition. Your last paragraph, it seems that is what is being proposed.

 

[Midwest]

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. I have found places (commercial installations) where more than 350 amps are flowing though earth, old gas pipes, old water pipes because of this problem. When it happens, without PME, the 3-phases become unblanced and one may get 150 volts and another 350 volts rms. So customers equipment dies - and there are quite a few case studies of this happening - hundreds of homes with damaged equipment. PME tends to hold Neutral fairly well when this happens; some people get a little too high a voltage and some get dim bulbs, etc., that flags a fault without doing much damage.

The problem if you put and Earth rod in and bond it to metal water and gas pipes (ok, older houses with metal supply pipes) then stray current (mostly due to PME!) that has coupled onto those pipes can flow through the bonding and into the ground at your house. It does not matter much if all 3 services enter the house at the same place and are bonded there - but I have visited houses (especially council and ex-ones) where the water and sewage go along the back gardens but the electricity and gas come in at the front. I have measured 37 Amps flowing throug the bonding conductor from back to front of a terraced house (with a child who developed leukaemia) due to this problem - creating enormous magnetic fields (20 microteslas when UK average is 0.04 microtesla) inside the house as the go and return currents are taking completely different routes.

Easy way to tell if there is a problem is (always!) to put a clamp meter around the bonding conductors (in every installation!) and measure the current. It should be zero. If it more than an amp, I believe it should be rectified. Usual way is to insert a piece of insulating pastic pipe in the gas or water pipe wehere it enters the building to break the stray current path.

I see that you joined the forum recently. You do not appear to have listed your qualifications. I'm just a lowly domestic electrician, but I do not make comparisons with electricity and children suffering from leukaemia.

Please could you explain your experience and qualifications in these areas you have commented on.

 

[Wilko]

... creating enormous magnetic fields (20 microteslas when UK average is 0.04 microtesla) inside the house ...

Hi - at the risk of misquoting both you and Wikipedia, I'd appreciate your view on what they think is normal?

Orders of magnitude (magnetic field) - Wikipedia - https://en.m.wikipedia.org/wiki/Orders_of_magnitude_(magnetic_field)

 

[alasdairp]

I see that you joined the forum recently. You do not appear to have listed your qualifications. I'm just a lowly domestic electrician, but I do not make comparisons with electricity and children suffering from leukaemia.

Please could you explain your experience and qualifications in these areas you have commented on.

You are quite right to ask.
BSc in electrical and electronic engineering (1973), Post grad diploma in agriculture, MIAgE, MIEEE. I am also a Trustee of Children with Cancer UK (a Gt Ormond based St National Charity). Many years working in engineering firms, laterly in charge of electrical installations and plant safety, former member of OFFER (the old electricity Regulator) technical committee for Eastern England, many times involved in practical work with a number of RECs sorting difficult net and stray current problems, many practical commercial Consultation contracts to sort similar problems, founder member of Dept Health SAGE process which involved 50 people for several years of regular meetings - about half were senior managers and engineers from Nat Grid and the RECs/DNOs. I have my own small company designing and making EMF and RF measurement instruments, though I am trying to retire (aged 66). I also helped start and run www.powerwatch.org.uk. Easiest place to find details of the two SAGE Reports (they are now on the Government Archive site - but they keep moving them around) are:
Powerwatch News - 29/04/2007 - The SAGE Report - http://www.powerwatch.org.uk/news/20070429_sage_comments.asp
and the second report regarding distribution networks:
Powerwatch News - 09/06/2010 - SAGE recommends new EMF reduction measures - http://www.powerwatch.org.uk/news/20100609_SAGE.asp
(there is a download link for the actual Report)

 

[alasdairp]

Hi - at the risk of misquoting both you and Wikipedia, I'd appreciate your view on what they think is normal?

Orders of magnitude (magnetic field) - Wikipedia - https://en.m.wikipedia.org/wiki/Orders_of_magnitude_(magnetic_field)

View attachment 37593

Best place, by far, for information is the National Grid info site written and run by John Swanson who is a very senior scientific advisor on Nat Grid staff and also advises the ENA on these matters. He provides excellent very balanced and informative information on magnetic and electric fields. The Wiki page is very misleading - especially even stating the Earth;s geomagnetic field (which is static - i.e. DC) and quite different in nature ffrom time-varying EMFs - and even they vary with their effects depending on what sor of frequency they are.
Home | EMFs.info - http://www.emfs.info/

 

[Midwest]

You are quite right to ask.
BSc in electrical and electronic engineering (1973), Post grad diploma in agriculture, MIAgE, MIEEE. I am also a Trustee of Children with Cancer UK (a Gt Ormond based St National Charity). Many years working in engineering firms, laterly in charge of electrical installations and plant safety, former member of OFFER (the old electricity Regulator) technical committee for Eastern England, many times involved in practical work with a number of RECs sorting difficult net and stray current problems, many practical commercial Consultation contracts to sort similar problems, founder member of Dept Health SAGE process which involved 50 people for several years of regular meetings - about half were senior managers and engineers from Nat Grid and the RECs/DNOs. I have my own small company designing and making EMF and RF measurement instruments, though I am trying to retire (aged 66). I also helped start and run www.powerwatch.org.uk. Easiest place to find details of the two SAGE Reports (they are now on the Government Archive site - but they keep moving them around) are:
Powerwatch News - 29/04/2007 - The SAGE Report - http://www.powerwatch.org.uk/news/20070429_sage_comments.asp
and the second report regarding distribution networks:
Powerwatch News - 09/06/2010 - SAGE recommends new EMF reduction measures - http://www.powerwatch.org.uk/news/20100609_SAGE.asp
(there is a download link for the actual Report)

Quite a CV.

Not sure about linking cancer with electricity though, but whom am I to say. But on that point, someone started a thread on here recently, worried (quite so) about purchasing a property near HV python for these reasons. So I do think you should be careful about giving your opinion on these matters, whatever your qualifications IMO.

 

[DPG]

HV python - brill

 

[Midwest]

HV python - brill

Did that for sparksburnout

 

[Wilko]

. The Wiki page is very misleading - especially even stating the Earth;s geomagnetic field (which is static - i.e. DC) and quite different in nature ffrom time-varying EMFs - and even they vary with their effects depending on what sor of frequency they are.
Home | EMFs.info - http://www.emfs.info/

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.

 

[HandySparks]

I have found atool that does the job for that, but a decent SDS hammer drill to do the job is bigger than most of us have in our tool kit as the norm. It may need 10kg hammer in some types of ground as nothing smaller will sufffice. I would be interested to know from anyone what they have found that fits the bill. I have seen a few recommended tools such as Makita and Bosch or Dewalt like in the attached picture.
http://www.electriciansforums.co.uk/attachments/banging-a-rod-jpg.15634/

I guess if you have particularly difficult hard ground, then a bigger tool is the only answer.

Adapters/adaptors are easy to make. For example, find a cheap tool with a shank that's slightly bigger than the earth rod. Cut the cutting end off and fix a sleeve over the end to locate over the rod. Sleeve can be a metal tube, plastic pipe, whatever.

If I could find mine, I'd put up a pic!

 

[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