Late 50s(?) domestic electrical distribution boards

[paulsherwin]

Did there used to be a government or military bunker in the vicinity by any chance? That might explain why a warning siren was located in a sparsely populated rural area.

[Aaamusements]

I completely missed the siren thing the first time, it's not a very clear picture on tablet.
Not like any public sirens that I am aware off.
Very odd!

[julie_m]

Originally Posted by Aaamusements

But if the neutral had become disconnected then there would be no earthing at all? The multiple earths are on the poles outside. If we exclude the possibility of a dodgy old TT connection on the house that is.

If the Neutral in your house becomes disconnected from the incoming Neutral cable, it's still tied to your internal Earth wiring via the connector block where the wires enter -- and to the Neutral point of the substation through the actual Earth to where it's (presumably) still connected in the next house. This will raise the Neutral impedance sufficiently to take out the RCD.

There are still places where a disconnection would be really dangerous -- potentially applying live mains, via the combined impedance of your appliances in parallel, to exposed metalwork -- but such a disconnection would be no less dangerous in any other earthing system.

[Skywave]

Originally Posted by Techman

It is getting more unusual to see these overhead lines.

Not down here in south Somerset it isn't - they're everywhere! Direct feeds from pole to house in nearly every case. I'm yet to discover the interference level to short-wave radio reception as a result - but I fear the worst.

Al.

[Aaamusements]

Originally Posted by ajs_derby

If the Neutral in your house becomes disconnected from the incoming Neutral cable, it's still tied to your internal Earth wiring via the connector block where the wires enter -- and to the Neutral point of the substation through the actual Earth to where it's (presumably) still connected in the next house. This will raise the Neutral impedance sufficiently to take out the RCD.

There are still places where a disconnection would be really dangerous -- potentially applying live mains, via the combined impedance of your appliances in parallel, to exposed metalwork -- but such a disconnection would be no less dangerous in any other earthing system.

Relies on sufficient equipotential bonding... So yes, it's dangerous in any system but in the one above it could easily be lethal.

[julie_m]

I really can't see how it's any more dangerous to have multiple redundant connections between Neutral and Earth.

If you lose your incoming neutral, you still have an Earth connection, and that is bonded to Neutral upstream of the meter. So there is still some sort of a return path. The added Neutral impedance, via yours and your neighbours' Earth stakes and the ground in between, will trip an RCD at much less than a dangerous voltage.

If many of the redundant Neutral-Earth connections failed simultaneously, it might be dangerous. But that's even more unlikely than losing one.

[Aaamusements]

At this point I will just agree to differ, as it seems that either one or both of us has probably misunderstood what the other is saying.

[Techman]

Still, an interesting discussion on neutrals and earths.

I've just been looking at my 'original' photo of that 60 Amp isolator and there are four pieces of 'Dymo' label on it. The first piece says 'swimming pool', the second along top row says 'main isolator', the bottom row left says what looks like 'PNC system'. Now if I look at the way that Dymo label maker stamps out its letter 'E' it tends to not emboss the middle bar of the letter very well making it look like a 'C'. The 'N' still looks like an 'N', but I think it could be an 'M' which would make it read 'PME SYSTEM', although I still can't see any earths on the poles outside. The last label says '30 Amp fuses'. It also says 415v written in felt pen on that white box - I don't know what the other word is written next to it. I should have taken more notice at the time, but it was a small dark room below the stairs through a door about 3ft high and down a couple of steps, the floor being a foot or so below ground level, although it wasn't damp.

There is a more recent conservatory fitted to one end of the building and I guess that when it was wired up for power that the electrician put in a fresh circuit for it - I think that open double socket box is to house excess slack wiring and would have had a cover fitted. I think that 'others' have been in there messing and have removed the cover and not put it back - if you look closely you can see something on top of that 60 Amp isolator box that looks like a white cover, or even two. The other thing is that it could have been an actual double socket just for that switch room, but the home owner decided to connect his new conservatory supply into it - I was told that it was thought that he'd built the conservatory himself.

Skywave asks about the possible short wave radio interference. Where I used to live just across the road from this place, the interference from the supply cables was dreadful. I complained to the electricity board a number of times but they never managed to cure it. I had been suggested that an earth had come adrift on a pole somewhere (PME System?), but I remember that the only time reception was clear was during very wet weather or very misty/foggy weather. The impedance of the mains at my old house was bad, too. The voltage was often on the low side and the lights would dip if you switched the kettle on or anything else that took any current. I used to do electric welding sometimes - that was fun! It used to take the house lights down to a dimming flicker! I can only guess what effect it had on my neighbour - this house. During an evening, the lights would dip at different times for about three minutes and then come back up again all on there own and I knew it would be the people in the house here putting their electric kettle on for a cup of tea that was affecting the supply at my old house. As an experiment, I once turned on everything I could in the house and managed to get the mains down to just below 200 volts! I complained a number of times and they told me that they would alter a tapping on the 'transformer', which they did and things were as bit better after that. This brings me to the next bit where I'll describe the complete power run from this 'said' transformer.

There's a total of nine poles in this power run from start to finish. One pole carrying 11KV and a transformer, six carry 3 phase 415v and 2 carry just single phase 240 volts.

Down a lane from my old house and near where a farm house had once stood, although it had long gone before I lived there, is a large wooden pole carrying an 11KV line across the fields. This pole had a transformer high up on it. I suspect this was an original from the 50s. Three connections went into this transformer via insulators. A large pitch wound cable came out of it and went down the pole and underground. I never knew exactly where this cable ran until it came back up again in the far corner of the garden of my old house near the road, where it went up a pole which I received a 'payment' for when I lived there. Somewhere underground (I never found out exactly where) there must have been a spliced in join, where what seemed like a rather thin lead sheathed cable wound in a black bitumen type covering brought one of the phases underground to a pole in the middle of my garden behind the house. I 'found' this cable by accident one day while digging up a blocked drain in the garden - it wasn't very deep! It then went up this pole where two separate wires with what looked like taped up joins half way along went to insulators on a bracket on the corner of the house. You could lean out of an upstairs window and touch the live connections - you could certainly put your AVO probes on them to test the state of the mains - shocking! They did eventually upgrade this connection during one of my complaints about low and variable mains voltage. There were signs of another connection from this pole which would have been another single phase connection to a couple of cottages that had once stood close by, but had been knocked down long before I lived there.

So, the underground 3 phase supply has now reached and gone up the pole in the corner of my old garden where it crosses over above the road to another pole in the corner of the garden of this house. The cables then go to another pole near the other corner of this garden as shown in the first two pictures below. This pole is on, but just outside, the boundary fence of this property. The cables then turn a corner and head towards this house. You'll notice a single phase connection of two wires leading off from this pole to another small pole (not shown) on the plot of land beyond the end of the garden where another small house once stood. I remember this house when I lived there, but it was never lived in and was in a state of collapse even then and is now gone altogether, although its electrical connection remains to the plot.

The cables run down the side of the garden to another pole which is on, but just outside, the boundary. they then run to the pole (shown originally) at the rear of this house. Three phases run from this pole into the house. The three phase overhead lines then continue from this pole to one last pole which is just over the boundary and belonging to the buisiness next door. This is the very end of the power line run.

Just getting back to the question about the siren - I was talking to someone about this siren and they told me immediately what they thought it was and I agree, but we could both be wrong. There are military bunkers around, but the nearest is a few miles away, and if I say that this particular area would probably not be suitable for such a thing, then this may be a big clue. There is also a clue in the first and third picture below, if we're thinking along the same lines. This may be difficult, but I'm wondering if anyone's going to guess.
Also, some may spot that possibly another four poles can be seen in the distance in photo three - well, I can see them on the original, although they may not show on the forum version. I can tell you that these other poles are in no way connected with this power supply being discussed here. Pictures:-

[hannahs radios]

When I lived near Newbury our council estate had overhead power lines there were 5 wires one street lamp supply 3 phases and neutral this was later converted to PME supply as a lot of them were I believe. I clearly remember that medium and shortwave reception was often spoiled by lots of clicks and crackles must be a thing with OH wiring. I still have music tapes recorded off the radio at the time so I'm not relying on memory reception was grotty it seems. Where I live now we have underground mains but we sometimes get pronounced voltage sags shifts of up to 10 volts at a time its not caused by anything in our house our 8.5 KW shower doesn't shift the voltage by that much

[Nickthedentist]

I have to say that I find this kind of investigation fascinating. Wouldn't it have been interesting to talk to the last owner!

[paulsherwin]

Overhead power is rarely seen in British urban areas, but you do come across it in odd places. The village of South Hinksey is less than 2 miles from the centre of Oxford and inside the ring road, but still has overhead power, as can be seen from Google Streetview. Bizarrely there is a Supergrid termination point only a hundred yards away, where power coming into Oxford goes underground. This is clearly visible on the satellite image to the north east of the village near to the railway line.

[AndiiT]

Hi,
On the subject of overhead power lines there are still quite a few in this neck of the woods, which is bordering Teesside, East Cleveland (formerly the East Riding of Yorkshire) and North Yorkshire, in fact there are overhead power lines less than two miles down the road from us and also in a couple of neighbouring villages on the coast route to Whitby.

On the subject of other items fitted to the distribution pole in one of the original pictures, did I spot a Bell 80D at the top of the pole above the sirens? If so this would suggest to me that there may have been some kind of business, where work was done outside, associated with a building close by and the Bell was connected across the appropriate phone line at the distribution box (unusually) to alert an incoming call.

Regards

Andrew

[Nickthedentist]

Originally Posted by AndiiT

On the subject of other items fitted to the distribution pole in one of the original pictures, did I spot a Bell 80D at the top of the pole above the sirens? If so this would suggest to me that there may have been some kind of business, where work was done outside, associated with a building close by and the Bell was connected across the appropriate phone line at the distribution box (unusually) to alert an incoming call.

That seems logical. There seems to have been farming in the locality according to the OP.

Do you think the "sirens" were some type of GPO klaxon?

[Techman]

On the subject of short-wave radio interference - I wish it had been just clicks and crackles. When it 'was' there it was just a constant 'hash'. I actually blamed that transformer taking the 11KV down to 415V as it wasn't that far from me down that lane. It did seem that damp and wet conditions seemed to 'earth' whatever was causing it. So if you've only got normal 'low voltage' overhead lines, then it might not be quite so bad. Where I live now the area is on underground feed, but there's a different sort of 'hash' caused by the usual more modern things, as we all know, such as solar panel installations etc.

I believe that the business next door was once part of this property, but it would have been many years ago, longer ago than I can remember, probably the 1960s when it was all one place. It used to be an old style garage with petrol pumps where the man came out of the little office to fill your tank for you. I remember going there for petrol years ago. There's still workshops there, but the pumps went years ago and it has now got its own living accommodation there. The bell probably dates from this time. I think that siren is something different altogether, though.

I didn't know the people who have been living at this house since I moved away from the area as they moved there after I left.

[G6Tanuki]

Originally Posted by AndiiT

On the subject of other items fitted to the distribution pole in one of the original pictures, did I spot a Bell 80D at the top of the pole above the sirens?

About 1/2 mile from where I grew up there was a small sawmill that had an identical external repeater-bell for its phone. On a still summer day it could be heard over quite some distance. I could easily imagine how a house with a large garden might have such an arrangement to summon the occupants back from the gazebo to the house when they needed to receive a call.

[Herald1360]

Flood warning siren? Flat low lying area with high water table, perhaps?

[Refugee]

We have overhead power but not on poles.
The cables are just clipped to the houses and strung between them.
It goes right past my workshop window.
At the end house the cable goes underground via a cast iron junction box.

[julie_m]

I was thinking the third picture could be a mineshaft; but that would not tally with there being no mains electricity in the area, as industry needs power.

[paulsherwin]

More likely to be an access point for a big drainage system, but it could be anything.

[russell_w_b]

Originally Posted by Herald1360

Flood warning siren?

Is it a siren? I can't make out any slits in the end. Is it indeed a noise-producing device?

On the east coast from Essex up to Lincolnshire (and possibly elsewhere) the ex-WB controlled 'cold war' sirens were still extant back in '02 and were used for flood warning. But we're talking 10kW 3-Phase double-enders here, not the titchy little shrill things the size of the thing on the pole.