Highly Unusual Doubled Up Earthing Wires on UK Domestic Installation 5

[gwolf2]

I have recently bought a 1960's bungalow in the UK which has a highly unusual (but probably safe) 240v electrical wiring arrangement. I thought I'd check with some experts before ripping 50% of it out. I have had no luck polling local electricians who either don't know or don't want to get involved. I have an electrical inspection certificate from 2013 but that electrician is no longer around. It's an interesting case so please read on.

Basically the house has a HUGE secondary earthing circuit independent of the normal 3 core ring main. It seems to be applied to everything but the lighting circuits (although I may simply not have found those wires yet). Every wall outlet socket has the normal 3 core ring main including earth AND a second independent earth wire which leads up into the loft and is attached to two 6ft long 2 inch x 1/4 inch copper bus-bars mounted on the roof beams. All meticulously executed and labelled. Furthermore every piece of water and gas pipe in every room has the same. The wires are fairly high capacity, of the order of 6-10 mm^2 cross section and there are about 40 connected by large bolts to the bus-bar. There are also 4 large wires of the order of 10mm^2 bolted to a copper plate in the floor near the incoming meter. Wow.

My gut feeling is that the previous owner (a now deceased ex Marconi worker) was a bit odd and/or had once had a bad experience with electricity. Maybe he was trying to create some sort of Faraday cage to protect his mind from cosmic rays or cold war death rays? I noticed an Ethernet connection in the spacious but otherwise basic loft which would be slightly unusual for a retiree of that generation. It is rumoured by neighbours that he used to have a lot of computers up there and 'worked from home', which I find highly unlikely. Maybe he needed an exceptionally clean or stable electrical supply for something? I have not yet found any high powered supply wires to the loft or anywhere else to indicate high power kit he may have been running.

Anyway. Has anyone seen anything like this before, for which there may be a legitimate reason, and which might still be applicable to the property?

All comments welcome before I gradually remove all of these extra earths.

Regards,

Gwolf

 

[ScottyUK]

You won't find that in BS 7671! Sounds like the kind of lunacy that the 'audiophile' community periodically embark upon, or maybe a radio ham clinging to the frayed edge of sanity.

 

[DTR2011]

"Sounds like the kind of lunacy that the 'audiophile' community periodically embark upon". There is a high end audio store near me that sell $30k speaker wires. I've even tried to get them explain how speaker cable has a direction (arrows) listed.

 

[wroggent]

Had to google "3 core ring main". Is this method still used today in new construction?

 

[gwolf2]

Thought you would all like to see some photos too. It's unique. And don't get me started on the 'evolutionary, legacy plumbing' - both electrics and plumbing work very well but Wow.

 

[gwolf2]

looks like only one picture per post. see others

 

[gwolf2]

last one

 

[waross]

Probably overkill to correct a problem that was misdiagnosed in the first place.
He may have had some UPSs and or computers giving error signals.
I saw something similar but not so extensive.
A customer bought a computer and a UPS for his young nephew.
The receptacles were not grounded. (Third world).
He called in an electrician. I imagine that the electrician didn't have a clue and asked someone more knowledgeable who told him that the receptacles needed to be grounded.
"How do you do that?"
Connect the ground terminal with a green wire.
When I checked the faulty ground light was on on the UPS. (Not to be confused with a ground fault.)
I started checking the receptacles. Sure enough each receptacle had a green wire connected to the ground terminal. Looking further I discovered that all the green wires were connected together in the attic, but not connected to ground.
One more wire back to a ground terminal in the panel solved the issue.
This may have been a similar solution albeit much better executed.
When supermarkets in North America started installing central computers with data lincs to the individual cash registers they experienced a lot of problems.
They misdiagnosed the issue as interference between the line conductors and the ground conductor.
They demanded isolated grounds for terminal equipment.
The actual problem was that a great many of the supermarkets were wired when grounding or bonding of receptacles was still a work in progress.
Grounding methods in the early days was a work in progress. Many of the ground circuits had very high impedance.
Wiring in commercial buildings was frequently done with armoured cable. There was no ground conductor and the armour was used for the conductor. After a few years and a little corrosion, the continuity from turn to turn of the armour was lost and any current over the ground path took the long way around each wrap of the armour. The armour became a long spiral inductor with fairly high resistance.
Another wiring method was Electrical Metalic Tubing. This was connected with sleeves and an indent tool. If the installation was disturbed the joints became loose. After a few years a little corrosion would introduce high resistance to the joints.
Along came the data links. The designers, with no field experience on commercial wiring, assumed that a ground was a ground and all grounds were equal and tried to send data signals over the poor grounds.
Actually, by the time that the isolated ground receptacles appeared, grounding methods had improved so that in the majority of new construction, the grounding conductors were suitable for data links.
The isolated ground receptacles served a purpose on older buildings and on the odd problem building.
A solution to the wrong problem which came after it was needed.
You are probably looking at something similar here.
Over the years we saw problems blamed on poor grounds when the grounds were already properly isolated.
The techs had to work harder to find the real root of the problem.
We also saw techs compliment the electricians for a job well done on the grounding. They could tell that it was well done because of the quality of the signal. The electricians were giggling because it would have been so expensive to put in an isolated ground that they had cheated and made an ordinary code quality ground look like an isolated ground.



Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ScottyUK]

That service head on the incoming PILC cable appears to be PME, the main bonds to the water & gas services look undersized (6mm^2 perhaps?) and are those VIR tails from the service head? They are really old! The installation has quite a few deviations from the current regulations.

 

[zeusfaber]

Just me being suspicious here.

Are the meter tails connected the right way round (ie, is it measuring the current in the Live, like it ought to, or in the Neutral).

Sometimes when you see people stiffening up the Earth line, it's because they're preparing to connect some of their heavier loads between Live and Earth.

A.

 

[gwolf2]

Thanks very much for the helpful comments. I think we may be homing in on something here. I'll check out that ground near the meter. Carefully. Very carefully.

 

[gwolf2]

Zeusfaber, interesting , very interesting guess. I'll check that too.

 

[gwolf2]

I did a little more inspection. See better meter picture attached. It all looks OK but I am no expert. The small wire coming from beneath the four bolts was just a disconnected piece of metal. The 4 wire secondary earth is a piece of copper hammered into the ground (probably right down to the bedrock if I know this guy) and also connected to the normal house earth just before the meter.

It all just looks like a second high capacity earth running in parallel with the normal one. I can't tell by looking at it if the meter transponder is reading from live or neutral but it is properly tagged and sealed.

I like the UPS theory mixed in with a bit of paranoia and general madness. I might get the quality of that original earth checked out (not sure how to do it with my simple meters) and then just rip it all out over time.

gwolf

 

[itsmoked]

gwolf just directly post your pics please.

Use the

Keith Cress
kcress -

http://www.flaminsystems.com

 

[itsmoked]

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

A previous owner may have been using some equipment that required a good ground and discovered some deficiencies with the existing grounding system. I wouldn't be too quick to tear it out. It won't do any harm and it may have been put in to correct a deficiency.
That is not to say that I would not remove it, but I would leave it in place unless I had a pressing reason to remove it.
Thanks for the pics Keith.
Yours
Bill

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

You bet Bill.

I'm not seeing any other ground...
I'm with Bill on that too. Leave it until proven otherwise.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

Keith, Bill -

In the UK our distribution companies often use 'PEN' - protective earthed neutral cables in a 'PME' - protective multiple earthing - configuration whereby the neutral and earth are combined on the lead sheath of the PILC cable. The lead sheath is in contact with the mass of earth because the tarred jute serving is anything but waterproof and anything but an insulator: over a large area it provides a good connection to the mass of earth.

In the specific example above the neutral and earth are split out at the service head - the black item in the last photo - and the supply goes from a TN-C configuration on the distributor's side of the service head to a TN-S configuration within the customer's premises. I can see the earth from the PEN cable going to a metal earth block to the lower right of the service head, although it's been painted white. That's a less-than-ideal arrangement in itself because there's an entry provided on the right side of the service head to bring out the earth conductor rather than clamping or soldering to the lead sheath of the cable itself. There doesn't appear to be an earth going to the consumer unit, so I'm not sure what the earth continuity conductor of the flat T&E cables will be connected to, if anything. The earthing system in this house doesn't seem to follow any recognised convention, and may actually cause give rise to danger if a fault occurs elsewhere on the system.

 

[gwolf2]

Thanks Scotty, we seem to be burrowing down to the root cause here. Looks like a bad earth misdiagnosed as warros suggested may be one of the reasons for the loft spaghetti. I think it's time to get an electrician in to fix the original earth, check the system out generally, and disconnect the whole secondary earth nonsense. I'll pull those wires out as and when during the refurbishment.

This has been most helpful. My thanks to all.

David.

 

[ScottyUK]

Hi David,

If the main earth to the property is provided by the DNO - Distribution Network Operator - as part of their installation then they are obliged to maintain it under Regulation 24 of the Electricity Supply Quality and Continuity Regulations.

I'm certainly not saying anything is wrong with the PME earth, but if you want to get it checked for piece of mind then any decent electrician should be able to confirm that the earth is PME via the supply cable and verify that the earth path back to the source is sound with a few quick tests - all of which are straightforward if you have the right test gear. Based on the result of those tests you might find you need to speak to the DNO, or not.