On Fri, 3 Feb 2012 15:43:01 +0000, Mike Tomlinson
wrote:

In article , Dave Plowman (News)
writes

I've never quite understood why so many US towns seem to have overhead
wiring for mains. It's very unsightly.

The pole transformers aren't pretty either, though produce quite
spectacular pyrotechnics when they fail, which seems to happen more
often than it should.

Pole transformers here seem to be a resource of last resort, usually
in a rural backwater. They have multiple taps on them so the linesman
can do his best to recover as much of the 240 volts as he can, despite
their distance from the nearest substation.

d

On Fri, 03 Feb 2012 15:40:17 GMT, (Don Pearce) wrote:

On Fri, 03 Feb 2012 15:21:16 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Arny Krueger wrote:
Several hundred dollars worth of 12 gauge Romex and accessories were
involved. Simple things like putting the garbage disposal, microwave,
and toaster oven each on their own circuits make a big difference.

Romex is roughly what we call Twin and Earth in the UK?

What you're saying is radial circuits are commonly overloaded in some way?
All of those (and more) would work just fine on the one UK circuit.

Current price for 2.5mm TW&E in the UK (for final ring circuits) is about
45 gbp per 100 mtrs before tax.

Yes, 12 gauge Romex is just about equivalent to our 2.5mm twin and
earth in wire gauge. The problem of course, is that in the US it is
required to handle twice the current that we use for the same load.

About the same as if we used lighting spec cable for our sockets. Not
a great plan, I'd say.

d

Oops, I forgot. With a ring main we are effectively using it doubled
up - two runs in parallel. That means that we only load our domestic
cables a quarter as much as they do in the US. No wonder we don't
suffer from voltage sag here when we turn things on.

d

On 03/02/2012 15:59, Dave Plowman (News) wrote:
In ,
Mike wrote:
In articleMpudnU_xP60ibrbSnZ2dnUVZ5sydnZ2d@giganews. com, Arny Krueger
writes

You might be surprised to hear that in the Detroit metro area Aldi (under
the eponymous and Trade Joe brands) is probably the number 2 retailer of
groceries.

Not surprised, no. Aldi and their very similar competitor Lidl have
many stores in the UK. I think some of the food is of better quality
and cheaper than the established British supermarket chains (Tesco,
Sainsburys, Asda, Morrisons). Meat particularly is good.

I use Lidl for some things. Not fresh vegetables, though. Or meat. Dairy
products are good value as are most other non fresh things.
Their tools in general are excellent - far better than budget stuff
elsewhere. But are only ever on special offer so you need to look out for
them. Don't have an Aldi anywhere close.


SWMBO shops there a lot, including for meat, fruit and veg. Good quality
at good prices. We regularly shop at Lidl in the Netherlands too, where
the wine is especially good value.

--
Peter

"Don Pearce" wrote in message
...
On Fri, 3 Feb 2012 08:38:19 -0500, "Arny Krueger"
wrote:


"David Looser" wrote in message
...
"Arny Krueger" wrote

Seems like a lot of wiring and separate little boxes to handle not so
many circuits.

I presume that it provides service for more than just one little hotel
room.
Yes, that's the main incoming supply to the building. The grey unit at
the
bottom left is the supply company's terminating unit that inludes their
fuses. Above that is the meter, to the right of it is a neutral block,
and
beyond that an isolator (looks like a three-phase + neutral one). I'm
not
sure what the unit above the isolator is, but at the top of the wardrobe
are three consumer units, each, apparently, fed from a different phase.
The one on the right seems to feed just one, high-current, load.

In the US even fairly large homes and retail stores generally have just
two
boxes - a meter box and a distribution panel box. 120 volt and 240 volt
circuits are distributed from there.

There are exceptions. For historical reasons, my ca. 1933 home has 2
subpanels and should have 3. It also has a safety switch in a separate box
outside by the meter because the run to the main distribution panel in the
basement is so long. This place is really gerrymandered as its needs
increased dramatically over the years.

Intermediate-size buildings such as a large factory, apartment building or
superstore have a central meter and a few large breakers in just two
boxes,
and additional subpanels as needed.

Really large buildings distribute HV (e.g. 4,800 volts) inside the
building
and have transformer substations in various locations. The metering is
generally still centralized.

If there are multiple paying accounts within a building there will be
multiple meters and each has its own distribution infrastructure.


Do the 120V and 240V system share the same high voltage distribution
lines? I mean is the transformation done per house, per street or per
district? It just strikes me that with 240V available the requirement
for 120V should be dwindling. It really is too low for even
distribution within a house. I have experienced lights dimming
significantly when appliances are turned on in many American homes.

Also it doesn't allow high-power devices such as kettles to be driven from
120V, hence the tendency for water in the US to be boiled in a pan on a
cooker hob which much be horrendously slow (I know from when I've had to do
it on a gas or electric hob when the kettle was broken).

"Arny Krueger" wrote in message
...

"Don Pearce" wrote in message
...

Do the 120V and 240V system share the same high voltage distribution
lines? I mean is the transformation done per house, per street or per
district?

It is done as needed. In a residential neighborhood there may be several
transformers per block. There is a transformer in my back yard and I can
see the next one maybe 6-8 houses (on my side) down.

It just strikes me that with 240V available the requirement
for 120V should be dwindling.

240v has been widely avaiilable here since before WW2.

My expectations are that since power use is likely to decrease, and the
power drain of household equipment of a kind is generally decreasing,
there's no push for more 220 volt usage in homes.

220 volt portable houshold appliances are rare. Just a random thought but
the advent of 90-250 volt wall warts and other stuff with similar
switchmode power supplies are opening the door to future implementation of
more 220 volt house wiring.

The most recent *big* user of 240 volt power was air conditioning, but
almost all of that equipment that is going to exist has probably already
been isntalled, except of course new homes. I don't expect a lot of new
homes to be built for many years.

It really is too low for even distribution within a house.

I would say that its biggest problem is that 12 guage copper wire is
getting to be pretty expensive.

I have experienced lights dimming
significantly when appliances are turned on in many American homes.

Historical artifacts. I just rewired part of my daughter's ca. 1955 house
and all I can say is that we added a ton of new circuits and I saw many
strange things that we made go away.

Several hundred dollars worth of 12 gauge Romex and accessories were
involved. Simple things like putting the garbage disposal, microwave, and
toaster oven each on their own circuits make a big difference.

In the UK, all of these could be driven from one ring main without the need
for separate radials from the fusebox for each one. Most houses I've seen
just have two ring mains (one for upstairs, one for downstairs), separate
circuits for really high power devices (cooker, immersion heater, electric
shower circuit - if fitted) and one or two lighting circuits. Things like
microwaves would be fine in a ring main. Ring mains are fused at 30 A which
means you could have plug-in appliances to a total of 7.2 kW downstairs and
the same upstairs. Mind you, you have to be aware of the electricity company
master fuse which is (I think) around 60 A :-)

On Fri, 3 Feb 2012 16:24:45 -0000, "Mortimer" wrote:

Also it doesn't allow high-power devices such as kettles to be driven from
120V, hence the tendency for water in the US to be boiled in a pan on a
cooker hob which much be horrendously slow (I know from when I've had to do
it on a gas or electric hob when the kettle was broken).

I have one horrible memory of once being at a girlfriend's house in
New York (no, that wasn't the horrible bit). She was drying her hair.
The drier plug was hanging half out as they always do (bugger all
retention or location in a US mains plug) and it was almost glowing
red hot from the current.

d

In article ,
Arny Krueger wrote:
http://i92.photobucket.com/albums/l1...erWardrobe.jpg

Seems like a lot of wiring and separate little boxes to handle not so
many circuits.

I presume that it provides service for more than just one little hotel
room.

Here's something more representative:-

http://i139.photobucket.com/albums/q...akkies/002.jpg

--
*Atheism is a non-prophet organization.

Dave Plowman London SW
To e-mail, change noise into sound.

In message , David Looser
writes
"J. P. Gilliver (John)" wrote in message
...
In message , Mortimer
writes:
[]
While we're talking about electrical safety, what is the current (scuse
that unintentional pun) advice on extending the lead of a freezer? I know
you have to use cable that is rated for 13A (1.5 mm^2 wire rather than 1
mm^2) and conventional extension cables must be unrolled to avoid
inductive heating. But providing you use a cable of the correct
[]
I don't _think_ it's _inductive_ heating they're that concerned about -
just air cooling, or rather the lack of it when a cable is wound onto a
reel (and tightly, as it often is).
--

Indeed. It's a common error to assume that the reason that cable drums
should be unwound when in use is something to do with inductance. Possibly
because its a coil, and wire is commonly coiled up to create an inductor.
But in this case it is, as you say, simply a matter of air cooling, or more
to the point the lack of it. The inductance of an air-cored coil of
relatively few turns would be insignificant at 50Hz and in any case the
inductances of the two conductors largely cancel out.

David.



It's nothing to do with inductance. A moment's thought will show that a
cable drum of mains cable is wound non-inductively, as the forward and
return paths of the current run next to each other in the cable.
--
Chris Morriss

"Dave Plowman (News)" wrote in message
...
In article ,
Arny Krueger wrote:

Several hundred dollars worth of 12 gauge Romex and accessories were
involved. Simple things like putting the garbage disposal, microwave,
and toaster oven each on their own circuits make a big difference.

Romex is roughly what we call Twin and Earth in the UK?

Googling shows pictures that are nearly identical if not exactly identical.

What you're saying is radial circuits are commonly overloaded in some way?

Not commonly, but occasionally in older dwellings. Most of what you are
talking about is due to motor starting surges, so the light dimming is
pretty much cosmetic. Not that I would intentionally tolerate it.

All of those (and more) would work just fine on the one UK circuit.

Given that our toaster ovens use up about 95% of a 15 amp circuit, two of
them put a quick end to 15a fuses and pretty quickly open 15a breakers. The
larger microwaves are only a little lighter on the draw, so a microwave and
a toaster oven on the same circuit won't be very relaible, either. Ditto for
our larger electric coffee and tea pots. I don't know how to get around
that.


Current price for 2.5mm TW&E in the UK (for final ring circuits) is about
45 gbp per 100 mtrs before tax.

That checks out.


If my tables are right, 2.5 mm is about 10 gauge, which is a lot more
copper than our 12 gauge. Almost twice as much. We consider 10 gauge to be
suitable for 30 amp wiring, which would indeed handle two devices from the
list microwaves, toasters, coffee pots, etc. A garbage disposal could run
on the same circuit without tripping or frying anything. Probably no light
dimming, either. And, that is at 120 volts!

250 feet of 10/3 romex runs about $200. I wonder why people aren't
importing wire from the UK - your prices are pretty cheap!

..

"Don Pearce" wrote in message
...
On Fri, 03 Feb 2012 15:21:16 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Arny Krueger wrote:
Several hundred dollars worth of 12 gauge Romex and accessories were
involved. Simple things like putting the garbage disposal, microwave,
and toaster oven each on their own circuits make a big difference.

Romex is roughly what we call Twin and Earth in the UK?

What you're saying is radial circuits are commonly overloaded in some way?
All of those (and more) would work just fine on the one UK circuit.

Current price for 2.5mm TW&E in the UK (for final ring circuits) is about
45 gbp per 100 mtrs before tax.

Yes, 12 gauge Romex is just about equivalent to our 2.5mm twin and
earth in wire gauge. The problem of course, is that in the US it is
required to handle twice the current that we use for the same load.

Does not seem to be true. My wire tables say 2.5 mm diameter copper is more
like 10 gauge.