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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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*Five* wire overhead mains cables
On 16/04/2021 15:57, NY wrote:
I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA |
#2
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*Five* wire overhead mains cables
On 16/04/2021 16:25, NY wrote:
"Peter Able" wrote in message ... On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. With the phone wires on (as far as I could see) the same brown porcelain insulators as the 240 V mains wires? This is the wiring https://goo.gl/maps/7TY9tJ2LNZfzEGE46 and https://goo.gl/maps/YRgYsyz7K75p3KUZ6: the latter shows a separate phone wire swapping from below the five mains wires on the nearest post to the above them on the next post, which looks as if it could cause if the insulated phone cable was repeatedly blown against the un-insulated mains wires, eventually taking the phone insulation off and shorting the mains wires. Now, with an image, there's something to go on. Looking at the second link, the fourth cable from the top terminates at a house further on to right, and at a pole further to the left. It looks to be thinner, and is not obviously driven from 3-phase drives? So who knows? And wouldn't you - even if was only meant for for this or that, use an cable insulator/anti-rubbing item of the same kind as already in use in that area? PA |
#3
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*Five* wire overhead mains cables
I'm used to seeing three-wire (three phases) overhead mains wiring from
poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? |
#4
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*Five* wire overhead mains cables
"Peter Able" wrote in message
... On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. With the phone wires on (as far as I could see) the same brown porcelain insulators as the 240 V mains wires? This is the wiring https://goo.gl/maps/7TY9tJ2LNZfzEGE46 and https://goo.gl/maps/YRgYsyz7K75p3KUZ6: the latter shows a separate phone wire swapping from below the five mains wires on the nearest post to the above them on the next post, which looks as if it could cause if the insulated phone cable was repeatedly blown against the un-insulated mains wires, eventually taking the phone insulation off and shorting the mains wires. |
#5
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*Five* wire overhead mains cables
On Friday, April 16, 2021 at 4:25:24 PM UTC+1, NY wrote:
"Peter Able" wrote in message ... On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. With the phone wires on (as far as I could see) the same brown porcelain insulators as the 240 V mains wires? This is the wiring https://goo.gl/maps/7TY9tJ2LNZfzEGE46 and https://goo.gl/maps/YRgYsyz7K75p3KUZ6: the latter shows a separate phone wire swapping from below the five mains wires on the nearest post to the above them on the next post, which looks as if it could cause if the insulated phone cable was repeatedly blown against the un-insulated mains wires, eventually taking the phone insulation off and shorting the mains wires. Only four wires coming from the pole mounted transformer, the fifth wire just seems to go from pole to pole down the street |
#6
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*Five* wire overhead mains cables
NY wrote:
I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. But I'm mystified about five-wire mains. TN-S system (not TN-C-S) L1, L2, L3, N, PE |
#7
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*Five* wire overhead mains cables
On 16/04/2021 16:25, NY wrote:
.... This is the wiring https://goo.gl/maps/7TY9tJ2LNZfzEGE46 ... The top three are the three phases. The bottom one is neutral and the one between, which, if you look carefully is not insulated, is earth. It was a common arrangement in some areas. -- Colin Bignell |
#8
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*Five* wire overhead mains cables
In article , Peter Able wrote:
On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA In the Uk you can't mix mains and telephone. % wire 3 pases, neutral & earth. -- from KT24 in Surrey, England "I'd rather die of exhaustion than die of boredom" Thomas Carlyle |
#9
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*Five* wire overhead mains cables
On 16/04/2021 16:47, Andy Burns wrote:
NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. But I'm mystified about five-wire mains. TN-S system (not TN-C-S) L1, L2, L3, N, PE See photo here (it's not good, and you'll have to zoom in a bit) https://ibb.co/7Cs99M2 A temporary 500kW generator was required recently to cover for some work on a nearby substation. It was connected up to the overhead lines nearby. There were five cables from the generator to the lines. The upper three were connected to, I expect, the three live phases (they are the upper three cables with the yellow insulated connectors). There were two further connectors (uninsulated?). They are the lower two in the photo, and both appear to be connected to the fourth line( below the three live phases), which I assume is the neutral. Would those two connections be neutral and earth from the generator to make a common neutral/earth connection? -- Jeff |
#10
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*Five* wire overhead mains cables
On 16/04/2021 19:27, Scott wrote:
On Fri, 16 Apr 2021 18:46:38 +0100, "NY" wrote: "charles" wrote in message ... In article , Peter Able wrote: On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA In the UK you can't mix mains and telephone. 5 wire 3 phases, neutral & earth. Depends what you mean by mix. Both around here - and in NY's links - you can see telephone lines sharing the poles. What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? There'll always be some imbalance. Different loads, and not every third house on the same phase. Are you saying that telephone wires in the UK always require separate poles and can't be carried on electricity poles? I thought they picked up hum if they ran parallel to an electricity cable. They do, but in both wires - so that's ok (theoretically) PA |
#11
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*Five* wire overhead mains cables
"charles" wrote in message
... In article , Peter Able wrote: On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA In the UK you can't mix mains and telephone. 5 wire 3 phases, neutral & earth. What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? Are you saying that telephone wires in the UK always require separate poles and can't be carried on electricity poles? |
#12
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*Five* wire overhead mains cables
On Fri, 16 Apr 2021 18:46:38 +0100, "NY" wrote:
"charles" wrote in message ... In article , Peter Able wrote: On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA In the UK you can't mix mains and telephone. 5 wire 3 phases, neutral & earth. What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? Are you saying that telephone wires in the UK always require separate poles and can't be carried on electricity poles? I thought they picked up hum if they ran parallel to an electricity cable. |
#13
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*Five* wire overhead mains cables
In article , nightjar
writes On 16/04/2021 16:25, NY wrote: ... This is the wiring https://goo.gl/maps/7TY9tJ2LNZfzEGE46 ... The top three are the three phases. The bottom one is neutral and the one between, which, if you look carefully is not insulated, is earth. It was a common arrangement in some areas. We have an extra cable, not insulated around here which is a low voltage data signal carrier. -- bert |
#14
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*Five* wire overhead mains cables
On Fri, 16 Apr 2021 18:41:44 +0100, Peter Able wrote:
On 16/04/2021 19:27, Scott wrote: On Fri, 16 Apr 2021 18:46:38 +0100, "NY" wrote: "charles" wrote in message ... In article , Peter Able wrote: On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA In the UK you can't mix mains and telephone. 5 wire 3 phases, neutral & earth. Depends what you mean by mix. Both around here - and in NY's links - you can see telephone lines sharing the poles. What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? There'll always be some imbalance. Different loads, and not every third house on the same phase. Are you saying that telephone wires in the UK always require separate poles and can't be carried on electricity poles? I thought they picked up hum if they ran parallel to an electricity cable. They do, but in both wires - so that's ok (theoretically) How come I am having problems in my flat where my final extension has a hum and the cable runs very close to the electric ring main. The other extensions do not have this issue. |
#15
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*Five* wire overhead mains cables
On 16/04/2021 19:28, bert wrote:
In article , nightjar writes On 16/04/2021 16:25, NY wrote: ... This is the wiring https://goo.gl/maps/7TY9tJ2LNZfzEGE46 ... The top three are the three phases. The bottom one is neutral and the one between, which, if you look carefully is not insulated, is earth. It was a common arrangement in some areas. We have an extra cable, not insulatedÂ* around here which is a low voltage data signal carrier. The setup shown is typical of pre-war rural area electricity distribution systems, which are as I describe. -- Colin Bignell |
#16
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*Five* wire overhead mains cables
In article , NY wrote:
"charles" wrote in message ... In article , Peter Able wrote: On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA In the UK you can't mix mains and telephone. 5 wire 3 phases, neutral & earth. What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? Are you saying that telephone wires in the UK always require separate poles and can't be carried on electricity poles? that certainly used to be the safety requirement. Nobody wanted 240v on their telephone. -- from KT24 in Surrey, England "I'd rather die of exhaustion than die of boredom" Thomas Carlyle |
#17
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*Five* wire overhead mains cables
On Fri, 16 Apr 2021 20:36:02 +0100, charles
wrote: In article , NY wrote: "charles" wrote in message ... In article , Peter Able wrote: On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA In the UK you can't mix mains and telephone. 5 wire 3 phases, neutral & earth. What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? Are you saying that telephone wires in the UK always require separate poles and can't be carried on electricity poles? that certainly used to be the safety requirement. Nobody wanted 240v on their telephone. I would have thought 240V at the exchange would be an even bigger problem. |
#18
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*Five* wire overhead mains cables
"Scott" wrote in message ... On Fri, 16 Apr 2021 18:46:38 +0100, "NY" wrote: "charles" wrote in message ... In article , Peter Able wrote: On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA In the UK you can't mix mains and telephone. 5 wire 3 phases, neutral & earth. What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? Are you saying that telephone wires in the UK always require separate poles and can't be carried on electricity poles? I thought they picked up hum if they ran parallel to an electricity cable. Nope, because they are twisted pairs. |
#19
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*Five* wire overhead mains cables
On 16/04/2021 16:25, NY wrote:
"Peter Able" wrote in message ... On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? P1, P2, P3, N, E Telephones - well it is around here. With the phone wires on (as far as I could see) the same brown porcelain insulators as the 240 V mains wires? This is the wiring https://goo.gl/maps/7TY9tJ2LNZfzEGE46 and https://goo.gl/maps/YRgYsyz7K75p3KUZ6: the latter shows a separate phone wire swapping from below the five mains wires on the nearest post to the above them on the next post, which looks as if it could cause if the insulated phone cable was repeatedly blown against the un-insulated mains wires, eventually taking the phone insulation off and shorting the mains wires. It is an optical illusion the phone line is below the mains wiring (and in prehistory the mains was probably insulated but not any more). Ours failed by having strips of the rubber insulation fall off and short adjacent phases in bad wet weather with much arcing and sparking. The phone line goes from low position on an electric pole to a higher phone pole set back from the electricity lines so there is no danger of them rubbing together. Phone is below mains wiring on our poles. My own village was wired about like this until the insulation fallign off kept bring the entire network down. It was replaced by three core aluminium conductors platted around a steel hawser down the middle. The new wiring proved strong enough to resist a tree falling across it although the supporting poles ended up like bananas and one side of the street was disconnected from supply. I have a picture of it somewhere. My hedge has still not quite recovered from the damage. The poles now have little plaques on "unsafe: do not climb". -- Regards, Martin Brown |
#20
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*Five* wire overhead mains cables
"Scott" wrote in message ... On Fri, 16 Apr 2021 20:36:02 +0100, charles wrote: In article , NY wrote: "charles" wrote in message ... In article , Peter Able wrote: On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA In the UK you can't mix mains and telephone. 5 wire 3 phases, neutral & earth. What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? Are you saying that telephone wires in the UK always require separate poles and can't be carried on electricity poles? that certainly used to be the safety requirement. Nobody wanted 240v on their telephone. I would have thought 240V at the exchange would be an even bigger problem. Nope, they have to have some protection against lightning strikes and that works for 240 volts too. In fact many street power lines have 11KV lines at the top of the poles too and sometimes someone drives into a pole and brings it down, with the 11KV lines with it. |
#21
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More Heavy Trolling by the Senile Octogenarian Nym-Shifting Ozzie Cretin!
On Sat, 17 Apr 2021 07:18:09 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again: Nope LOL ****ing unbelievable! -- Kerr-Mudd,John addressing the auto-contradicting senile cretin: "Auto-contradictor Rod is back! (in the KF)" MID: |
#22
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Lonely Auto-contradicting Senile Ozzie Troll Alert!
On Sat, 17 Apr 2021 07:26:23 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again: Nope BRUAHAHAHAHAHAHAHAAA!!! Senile cretin! -- Kerr-Mudd,John addressing the auto-contradicting senile cretin: "Auto-contradictor Rod is back! (in the KF)" MID: |
#23
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*Five* wire overhead mains cables
On Fri, 16 Apr 2021 18:46:38 +0100, NY wrote:
What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? A neutral is required - the houses will have a single phase supply, so will connect to one phase and neutral. Where you won't see a neutral is on the HV lines - the neutral is created at the transformer. A separate earth cable on overhead cabling is unusual - most often it's PME (so combined N/E) or TT (an earth rod at the house). It doesn't look like the earth cable in this example actually goes to most of the houses. https://goo.gl/maps/QGxRssmS2mkMJuKV8 and https:// goo.gl/maps/YEC7HKgHGvnC1Qy57 shows only two wires over the road to the house. The fifth wire terminates here https://goo.gl/maps/DqQoYJcoJCVptT2E7 - you can see that only four wires continue to the last pole, with the second from bottom missing. Where the line branches at Chapel Lane, there are again only four wires, and there's another four-wire branch just past at https://goo.gl/maps/ DqQoYJcoJCVptT2E7 . And the line ends here https://goo.gl/maps/ zovrrTaZbFnAePZP7 - where you can clearly see that the underground cable does not connect to the earth wire, only the phases and neutral. So I think there's a good chance this earth wire is mostly, or even completely, redundant. It's possible that it's been converted to PME but the separate earth wire not been removed. . Mike |
#24
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*Five* wire overhead mains cables
On 16/04/2021 23:02, Mike Humphrey wrote:
On Fri, 16 Apr 2021 18:46:38 +0100, NY wrote: What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? A neutral is required - the houses will have a single phase supply, so will connect to one phase and neutral. Where you won't see a neutral is on the HV lines - the neutral is created at the transformer. A separate earth cable on overhead cabling is unusual - most often it's PME (so combined N/E) or TT (an earth rod at the house). Are you saying that overhead mains wiring is *always* 4-wire (or 5-wire if there's a PE), with every house connected to one phase and neutral? And not houses connected to two of the phases? I *thought* I'd seen three wires rather than 4 in some cases. But I may well be mis-remembering it. |
#25
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*Five* wire overhead mains cables
On 17/04/2021 00:06, NY wrote:
On 16/04/2021 23:02, Mike Humphrey wrote: On Fri, 16 Apr 2021 18:46:38 +0100, NY wrote: What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? A neutral is required - the houses will have a single phase supply, so will connect to one phase and neutral. Where you won't see a neutral is on the HV lines - the neutral is created at the transformer. A separate earth cable on overhead cabling is unusual - most often it's PME (so combined N/E) or TT (an earth rod at the house). Are you saying that overhead mains wiring is *always* 4-wire (or 5-wire if there's a PE), with every house connected to one phase and neutral? And not houses connected to two of the phases? I *thought* I'd seen three wires rather than 4 in some cases. But I may well be mis-remembering it. Der!!! I *am* misremembering it. Neutral should be virtually at earth potential (*), not at one of the phase potentials. Of *course* there has to be a separate neutral line to make this happen ;-) (*) I believe in some installations, neutral is actually bonded to earth at the premises. |
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*Five* wire overhead mains cables
On 16/04/2021 15:57, NY wrote:
I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Jump a couple of meters down the road and then you see this https://goo.gl/maps/WQQhtqdtJCyLf6c77 WTF? -- Adam |
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*Five* wire overhead mains cables
In message , Peter Able
writes On 16/04/2021 19:27, Scott wrote: On Fri, 16 Apr 2021 18:46:38 +0100, "NY" wrote: "charles" wrote in message ... In article , Peter Able wrote: On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA In the UK you can't mix mains and telephone. 5 wire 3 phases, neutral & earth. Depends what you mean by mix. Both around here - and in NY's links - you can see telephone lines sharing the poles. What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? There'll always be some imbalance. Different loads, and not every third house on the same phase. Are you saying that telephone wires in the UK always require separate poles and can't be carried on electricity poles? I thought they picked up hum if they ran parallel to an electricity cable. They do, but in both wires - so that's ok (theoretically) Do we actually have 'utility poles' in the UK? They are standard practice in the USA, where they carry power, phone, cable TV etc (but, as far as I know, not gas and water!), and I've seen them in Belgium - but they must be pretty rare in the UK. -- Ian |
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*Five* wire overhead mains cables
ARW wrote:
https://goo.gl/maps/WQQhtqdtJCyLf6c77 WTF? insulating spacers to stop the phases getting too close in the wind? |
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*Five* wire overhead mains cables
Many moons ago down a country lane in Cornwall, I was young kid and we all
were stopped in our tracks by a team with a cherry picker doing something on the wooden pole at the side of the road. I think my dad got out to stretch his legs while we waited, and asked one of the blokes there why there were so many wires and apparently all bundled together every so often. They told him one of them was a steel wire to help stop the others stretching and did nothing else. Brian -- This newsgroup posting comes to you directly from... The Sofa of Brian Gaff... Blind user, so no pictures please Note this Signature is meaningless.! "Andy Burns" wrote in message ... ARW wrote: https://goo.gl/maps/WQQhtqdtJCyLf6c77 WTF? insulating spacers to stop the phases getting too close in the wind? |
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*Five* wire overhead mains cables
On 16/04/2021 18:46, NY wrote:
"charles" wrote in message ... In article , Peter Able wrote: On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA In the UK you can't mix mains and telephone. 5 wire 3 phases, neutral & earth. What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? Are you saying that telephone wires in the UK always require separate poles and can't be carried on electricity poles? yes. Climbing a power pole requires a hugely different safety regime from skinning up a telephone pole. it aint no silly 110v either. its 230v., -- No Apple devices were knowingly used in the preparation of this post. |
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*Five* wire overhead mains cables
On 17/04/2021 08:15, Andy Burns wrote:
ARW wrote: https://goo.gl/maps/WQQhtqdtJCyLf6c77 WTF? insulating spacers to stop the phases getting too close in the wind? Yep. I see it when I look further down. And a customer sent me this last week https://www.youtube.com/watch?v=uUow...tishPath%C3%A9 -- Adam |
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*Five* wire overhead mains cables
ARW wrote:
Andy Burns wrote: ARW wrote: https://goo.gl/maps/WQQhtqdtJCyLf6c77 WTF? insulating spacers to stop the phases getting too close in the wind? Yep. I see it when I look further down. And a customer sent me this last week https://www.youtube.com/watch?v=uUow...tishPath%C3%A9 But those "X" spacers which the commentator says are to stop them shorting the system, are on wires of the same phase! |
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*Five* wire overhead mains cables
In article ,
ARW wrote: On 17/04/2021 08:15, Andy Burns wrote: ARW wrote: https://goo.gl/maps/WQQhtqdtJCyLf6c77 WTF? insulating spacers to stop the phases getting too close in the wind? Yep. I see it when I look further down. And a customer sent me this last week https://www.youtube.com/watch?v=uUow...tishPath%C3%A9 before the days of H&S. No hard hats, no harnesses, even the club hammer had to safety chain ----- mmmm -- from KT24 in Surrey, England "I'd rather die of exhaustion than die of boredom" Thomas Carlyle |
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*Five* wire overhead mains cables
On 16 Apr 2021 at 19:27:27 BST, "Scott"
wrote: On Fri, 16 Apr 2021 18:46:38 +0100, "NY" wrote: "charles" wrote in message ... In article , Peter Able wrote: On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA In the UK you can't mix mains and telephone. 5 wire 3 phases, neutral & earth. What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? Are you saying that telephone wires in the UK always require separate poles and can't be carried on electricity poles? I thought they picked up hum if they ran parallel to an electricity cable. Our electricity and telephone come from the same pole outside our house. Openreach technicians say it is undesirable, but there is really nowhere else to put a pole without the mains and telephone drop wires interfering with each other. I've never seen a telephone cable on an 11kV pole though! -- Roger Hayter |
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*Five* wire overhead mains cables
On 17/04/2021 08:29, Brian Gaff (Sofa) wrote:
That sounds like a recipe for disaster to me. Hum induced voltages and damage putting dangerous voltages up a phone line. Brian Not at all. Induction makes little difference to our, notionally balanced, telephone network and the anchor points are well below the power cabling. There are several examples of this practice in the Google Map views the OP offered us. It is instructive to connect a phone line to a spectrum analyser and oscilloscope. When looking at either wire there is masses of pickup - predominantly of the Medium Wave - but some 50Hz, too. If you then couple both lines via a balun to the spectrum analyser/oscilloscope, you - thankfully - see way, way, way less unwanted stuff. PA |
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*Five* wire overhead mains cables
On 16 Apr 2021 at 19:45:55 BST, "Scott"
wrote: On Fri, 16 Apr 2021 18:41:44 +0100, Peter Able wrote: On 16/04/2021 19:27, Scott wrote: On Fri, 16 Apr 2021 18:46:38 +0100, "NY" wrote: "charles" wrote in message ... In article , Peter Able wrote: On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA In the UK you can't mix mains and telephone. 5 wire 3 phases, neutral & earth. Depends what you mean by mix. Both around here - and in NY's links - you can see telephone lines sharing the poles. What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? There'll always be some imbalance. Different loads, and not every third house on the same phase. Are you saying that telephone wires in the UK always require separate poles and can't be carried on electricity poles? I thought they picked up hum if they ran parallel to an electricity cable. They do, but in both wires - so that's ok (theoretically) How come I am having problems in my flat where my final extension has a hum and the cable runs very close to the electric ring main. The other extensions do not have this issue. You could try wiring this extension with proper twisted pair instead of ordinary telephone internal wiring which isn't (twisted, that is). -- Roger Hayter |
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*Five* wire overhead mains cables
On 17/04/2021 09:43, charles wrote:
In article , ARW wrote: On 17/04/2021 08:15, Andy Burns wrote: ARW wrote: https://goo.gl/maps/WQQhtqdtJCyLf6c77 WTF? insulating spacers to stop the phases getting too close in the wind? Yep. I see it when I look further down. And a customer sent me this last week https://www.youtube.com/watch?v=uUow...tishPath%C3%A9 before the days of H&S. No hard hats, no harnesses, even the club hammer had to safety chain ----- mmmm This one has a bloke in a suit going up the pylon https://www.youtube.com/watch?v=MGiT...tishPath%C3%A9 -- Adam |
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*Five* wire overhead mains cables
On 17/04/2021 09:52, Roger Hayter wrote:
On 16 Apr 2021 at 19:45:55 BST, "Scott" wrote: On Fri, 16 Apr 2021 18:41:44 +0100, Peter Able wrote: On 16/04/2021 19:27, Scott wrote: On Fri, 16 Apr 2021 18:46:38 +0100, "NY" wrote: "charles" wrote in message ... In article , Peter Able wrote: On 16/04/2021 15:57, NY wrote: I'm used to seeing three-wire (three phases) overhead mains wiring from poles along a street. Sometimes you get four-wire (three phases plus neutral). Modern wiring is a single larger cable which is the three (or four) wires twisted together. In each case, two wires (between two phases, or one phase and neutral) go to each house, with a different phase for each house or group of houses. But I'm mystified about five-wire mains. As far as I could see, all five wires were the same thickness and were each fastened to the same type of insulator on the wooden poles - so probably not three-wire mains and telephone. What would the fifth wire be used for? Telephones - well it is around here. PA In the UK you can't mix mains and telephone. 5 wire 3 phases, neutral & earth. Depends what you mean by mix. Both around here - and in NY's links - you can see telephone lines sharing the poles. What are the circumstances when overhead mains wiring has an extra earth wire, rather than the earthing being done at each house? I've never seen it before. Come to think of it, why do some installations have a neutral wire and some don't - are there cases where the nett load is expected to be unbalanced on the three phases, requiring an extra neutral? There'll always be some imbalance. Different loads, and not every third house on the same phase. Are you saying that telephone wires in the UK always require separate poles and can't be carried on electricity poles? I thought they picked up hum if they ran parallel to an electricity cable. They do, but in both wires - so that's ok (theoretically) How come I am having problems in my flat where my final extension has a hum and the cable runs very close to the electric ring main. The other extensions do not have this issue. You could try wiring this extension with proper twisted pair instead of ordinary telephone internal wiring which isn't (twisted, that is). If all of your extensions are simply connected across the incoming pair, then induced hum won't just affect one extension. PA |
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*Five* wire overhead mains cables
On 17/04/2021 09:11, Andy Burns wrote:
ARW wrote: Andy Burns wrote: ARW wrote: https://goo.gl/maps/WQQhtqdtJCyLf6c77 WTF? insulating spacers to stop the phases getting too close in the wind? Yep. I see it when I look further down. And a customer sent me this last week https://www.youtube.com/watch?v=uUow...tishPath%C3%A9 But those "X" spacers which the commentator says are to stop them shorting the system, are on wires of the same phase! https://www.youtube.com/watch?v=QLl9...l=User_Unknown -- Adam |
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