Power supply in USA & England

[Colly0410]

Here in England just about all low voltage power supply lines in urban & suburban areas are underground & use a big multi mega watts 3 phase transformer supplying from tens to hundreds of houses, each house is connected to one of the phases & neutral giving 240 volts at each socket/light fitting. Only in rural areas & in small villages (usually) is the supply overhead... When I was in the USA in most of the urban & suburban areas the low voltage supply was overhead lines with small pole mounted transformers feeding 1 or 2 houses, only the newest housing developments were supplied by underground lines. Anyone know why there's a difference?

[DavGoodlin]

I also noticed when visiting Scotland and England in the 70s and later in the 90-00's the receptacle outlets have all changed to meets British Standards (BS-#).

Now all are grounded and switched receptacles (outlets). Anything that plugs into these has large rectangular pins in a safety plug, where rpongs are de-energized before they are exposed, and the "hot" wire is FUSED. This wire is also color coded as brown on almost all appliances too. the neutral wire is blue IIRC. IE a lamp is fused at 3 amps, a kettle or coffee maker at 13 amps, etc.

It seems as if everywhere in the UK outlets had been replaced and the premises re-wired. This was accompanied by new wiring in thin white round cables, run along moldings and trimfeeding out of small plastic-enclosed breaker panels, usually mounted up high near the door. I bet folks had to spend a lot of sterling for those upgrades and they seemed to be found universally. Even the light switches are small square rocker switches.

In the US, many building's wired in the 1950s and early 60s lack grounded receptacles as did the "two-pin 220-volt" outlets in UK and Europe. small appliances, cords, lamps did not really have polarized two-prong plugs until recently. Our receptacle outlets were polarized (wide prong on neutral) even before they were grounded, but many extension cords and multi-taps, 3 ways, etc were NOT polarized until 20 years or so ago.

I think the US is so larger yet suburban in sheer land coverage, so overhead is the default due to its lower expense to run, visually inspect and maintain. Many more miles for sure.

Also the applicable standards are several, and not all cohesive in coverage: UL (what plugs in and to a lesser extent, outlets, wire and breakers) , National Electrical code (the receptacles, wire, raceways and breakers) and National Electrical Safety code (outdoor meters, poles, wires and transformers - even power generation)

Mostly, US has the freedom to be as el-cheapo as we want at our own personal risk -LOL. I made a 1940's era 60 amp overhead service last for 12 years. My excuse: the premesis is operated under Engineering supervision and under continuous improvement

As I added more outlets to rooms that had 1 or 2, I ran all new 12 gauge and grounded circuits. All new wire fed back to the over-sized 18-fuse panel, I still have wiring up to ceiling lights from the 1920s open "knob and tube" that is buried behind horse-hair plaster. It was 12 gauge, 6 inches apart and the rubber is still pliable and not cracking - highly unusual. The wiring was originally installed as the farmer installed lighting fed from a 32-volt generator until the Rural Electrification Association hooked all the farms up in the late 1940's.

Central AC install finally forced me to modernize to an underground pipe, a hundred feet long from the meter/main breaker on the property line, into a new 200 amp breaker panel in the basement in the old coal bin room. A new transformer was put on the pole by the power utility, which also raised my average line voltage from 114 to 124 volts, requiring me to take measures to prolong transformer and tube life in my old radios, tvs and HiFi supplies.

[Ed in Tx]

Originally Posted by DavGoodlin

I think the US is so larger yet suburban in sheer land coverage, so overhead is the default due to its lower expense to run, visually inspect and maintain. Many more miles for sure.

Pretty much what DavGoodlin said. My old neighborhood built up about 65 years ago still has the original utility poles which also support AT&T's old copper phone lines as well as their new fiber system, and Spectrum (ex-TWC) cable.. Looks like maybe 8 homes are served by one transformer on a pole behind my neighbor's house. Then maybe 20-30 years ago people started getting concerned about aesthetics and those ugly poles and power lines, so newer developments started going with the more expensive buried power and utilities. One thing we don't have to worry with our overhead lines and transformers is having a ground or buried transformer getting invaded by ants and shorting out the system. That happens sometimes. Occasionally we will hear on the news about a whole block of houses in a buried power lines area that got a big power surge through the 120V lines frying everything plugged in inside the homes.

[Electronic M]

I've seen buried lines in development communities as old as the 1970's.

Towns and other non-rural areas built before then seem to have overhead as grandfathered default...Depending on the PoCo and area those poles wires and transformers are sometimes WWII era originals, or stuff that gets upgraded every 20-30 years.

[dieseljeep]

Originally Posted by Ed in Tx

Pretty much what DavGoodlin said. My old neighborhood built up about 65 years ago still has the original utility poles which also support AT&T's old copper phone lines as well as their new fiber system, and Spectrum (ex-TWC) cable.. Looks like maybe 8 homes are served by one transformer on a pole behind my neighbor's house. Then maybe 20-30 years ago people started getting concerned about aesthetics and those ugly poles and power lines, so newer developments started going with the more expensive buried power and utilities. One thing we don't have to worry with our overhead lines and transformers is having a ground or buried transformer getting invaded by ants and shorting out the system. That happens sometimes. Occasionally we will hear on the news about a whole block of houses in a buried power lines area that got a big power surge through the 120V lines frying everything plugged in inside the homes.

Our transformers for the underground utilities are pad-mount, above ground green metal boxes. They have two access panels, one for the HV feeders and lightning arrestor and one for the secondary connections.

[Ed in Tx]

Originally Posted by dieseljeep

Our transformers for the underground utilities are pad-mount, above ground green metal boxes. They have two access panels, one for the HV feeders and lightning arrestor and one for the secondary connections.

Sounds exactly like the ones up in Carrollton TX that got invaded with fire ants and damaged several houses-worth of electronics. It was in the news.

[DavGoodlin]

Originally Posted by Ed in Tx

Sounds exactly like the ones up in Carrollton TX that got invaded with fire ants and damaged several houses-worth of electronics. It was in the news.

Ants are nutz about AC magnetic fields and probably swarmed en masse, somehow causing a flash-over between HV and LV compartments in the transformers. conductors on the 120/240 side are exposed lugs under those swing-up transformer covers. Not sure ants can disrupt a neutral connection but that can do the same level of damage in most cases.

A 20 year-old development across from us is 100% underground to boxes like dieseljeep describes. I saw some of the installs in progress before the PoCo covered the direct-bury cables with dirt. Two phases and a neutral are taken off a "drop pole" along the straight main road then run along the curvy development streets, under the grass. Each transformer has two HV phases coming in it could tap from, so if one shorts out, a backup second can be plugged on.

[Electronic M]

Where I live is a weird hybrid above/below set up. It is a very old/new rural/suburban neighborhood near a lake. Some houses look to be ~1930's others are 60's still more look to be built in the last 10-30 years. One block down hill close to the lake it is all overhead. Up by me the HV poles end about 2 doors down hill, go to a ground mounted transformer box across the street (the CATV continues on poles up hill), under the street, up a pole in my front yard, and to the back yard pole where it splits to 2 30's homes (overhead), and our late 70's home underground.

[bgadow]

The house I grew up in was on a dirt road out in the country. In the mid-70s, when I was maybe 5-6 years old, the county paved the road and the electric co-op moved the lines underground. Tons of fun for a little boy to watch! (Though I missed seeing the road grader going by periodically to smooth the dirt road) Anyway, by the late 80's the underground system had become very unreliable, with constant outages. It turns out the insulation was failing way sooner than expected. Eventually it all got replaced.

I think the co-op ran so much underground because it was seen as more reliable in the long-term, not just for looks, but that bad wire messed it all up.

[MadMan]

Originally Posted by Colly0410

When I was in the USA in most of the urban & suburban areas the low voltage supply was overhead lines with small pole mounted transformers feeding 1 or 2 houses, only the newest housing developments were supplied by underground lines. Anyone know why there's a difference?

Actually, the real reason most of our power lines are above ground on poles in the US (in major cities), is simply because that's the way we're used to doing it. The original reason why we started this, goes all the way back to the birth of centralized power generation.

/me leans back in arm chair and blows into bubble pipe.

You see, before there were 'utilities,' there was only one utility: gas. Gas in those days was called 'gas light' because that's just about all anybody used it for. It was only just starting to expand into the territory of stoves and perhaps a couple oddball things, not even heating yet. Then came the big bad competitor in the field centralized lighting: electricity. Which again, in those days, was considered (for the average consumer) to be only good for lighting homes. A direct competitor to gas light. Gas companies put up a fight.

So it makes more sense to deliver electricity underground, right? Safer, out of the way, not on ugly light poles. Yeah, they thought so too, back in the day. Unfortunately, a lot of gas companies insisted (in court) that they owned the rights to the ground. Which, I mean, they kind of did, right? The cities would've had to permit the laying of the pipes to the gas companies.

Oh well, they figured they'd put it up on poles, like those telegraph contraptions.

So, at present, we're not adverse to underground lines, as you noted, there are places where we have them. It's just that... well... the power companies are - and have been for over a century - equipped to install and maintain lines above ground on utility poles.

[Colly0410]

Interesting replies & I thank you all for them. Seems to be as Madman (love that moniker, lol) says "that's the way we're used to doing it!" Here in England it was usually the local council who supplied the gas & then electricity to urban & suburban areas so they'd share the ground as the council owned it. In rural areas & small villages where they never had gas they'd put in overhead lines for cheapness.

In the late 1940's the nationalised gas boards & electric boards took over the gas pipes & electric cables & would compete with each other. I lived in a village called Gotham in Nottinghamshire that had no gas supply & the electric was via overhead lines, every time it thundered the electric would go off. My niece still lives there & it's still overhead, they have a gas supply now though.

The gas & electric companies were privatised in the 1990's & offer a discount if you take both gas & electric from them. I'm with Thames Energy for both gas & electric, (they used to be London electricity board) I've got a discounted fixed price deal till 2018 with them..

[ppppenguin]

Since the US has a lower voltage supply than the UK the transformers need to be closer to people's houses to minimise voltage drop without spending a lot of money on thicker wires. So in urban and suburban areas in the UK is common practice to have a transformer in each street rather than one for every few houses.

One thing I noticed in the 'burbs around New York is that utility poles are rarely truly upright. A row of them looks like a group of drunks. Or perhaps that was just LILCO (Long Island Lighting Company) who don't have plumb bobs or spirit levels.

[hi_volt]

I guess it depends on where you live in the US. I grew up in the area just south of San Francisco in a house that was built in 1963, and all of power lines in my neighborhood were underground.

[DavGoodlin]

Originally Posted by ppppenguin

Since the US has a lower voltage supply than the UK the transformers need to be closer to people's houses to minimise voltage drop without spending a lot of money on thicker wires. So in urban and suburban areas in the UK is common practice to have a transformer in each street rather than one for every few houses.

Good point, 120 volts does require more copper and aluminum on the LV lines. I used to think the USA, Japan and the other places with 120 volts, did not have to be as thrifty with raw materials.

I noticed that the pole lines in Europe do not normally follow secondary roads but run direct from substations to villages across field and wood. A large, square pole-mount trans in a nearby field drops to 240 -3 phase WYE and 4 wires run from there in and around the village. In a small village in Germany, it seemed to hop from house to house as if walls were utility ppoles

[dieseljeep]

Originally Posted by DavGoodlin

Good point, 120 volts does require more copper and aluminum on the LV lines. I used to think the USA, Japan and the other places with 120 volts, did not have to be as thrifty with raw materials.

I noticed that the pole lines in Europe do not normally follow secondary roads but run direct from substations to villages across field and wood. A large, square pole-mount trans in a nearby field drops to 240 -3 phase WYE and 4 wires run from there in and around the village. In a small village in Germany, it seemed to hop from house to house as if walls were utility ppoles

Our 120/240 volt, 3 wire wiring scheme is going to be with us for a lot longer.
The NEC mandated that no voltage higher than 120 volts to ground be present in a residence or small commercial setting, where untrained personnel would have access to the electrical system. Three phase systems would be 120/208Y.
The older electrical schemes, 120/240 delta, 240 and 480 corner grounded delta are NLA, but are supported by the POCO. Good riddence.