Internal wiring of USA v UK mains plug

[N Cook]

Done correctly, a quality wire nut is a very secure and long lasting
connection. It's not simply a plastic cap, but a plastic casing over a
threaded springy metal insert which grips the wires very well. I have some
UK terminal blocks, and the problem with them is that there's no mechanical
bond between the wires, the contact point is small, and they can and do work
loose or corrode over time. They generally are ok, but neither method is
greatly superior to the other.

The double current isn't really much of an issue, our large loads are 240V
too, it's handy to have both voltages readily available.

You can get quality US style receptacles, problem is they're expensive so
few houses come with them. I like many things about the UK plugs, but the
thing I don't like is they're *huge* so things like power strips and
multi-gang outlets are really cumbersome.

Having discussed this in length with a friend in the UK, we've both come to
the conclusion that both systems have many advantages and disadvantages and
neither one is a clear winner.

Could someone direct me to pics of the 2 different types of plug/socket
system used in the USA to differentiate for medium and high power use, I
didn't even realise 220 or 240V was used residentially anywhere in the USA.

 

[Geoffrey S. Mendelson]

Could someone direct me to pics of the 2 different types of plug/socket
system used in the USA to differentiate for medium and high power use, I
didn't even realise 220 or 240V was used residentially anywhere in the USA.

There are several kinds depending upon the current rating and if 120
volts is used too. Before 1996, the ground pin was also used for neutral
for things like clothes dryers that had a 120 volt motors and timers and
240 volt heaters. I think that practice was stopped in the late 1970's.

In 1996, it became illegal. If your device has a mixture of 120 and 240
volt components, you need to have a four wire plug. I left the U.S. in
1996, so I've never seen them.

The simplest kind is used for air conditioners and is similar to a 120
volt grounded plug, with two flat blades and a rounded ground pin below
them in the middle. The difference is that the flat blades are the same
size and are horizontal instead of vertical.

I remember walking into an electronics store in SoHo (in Lyle Street?)
around 1983 and talking to the owner for a while. We got on to discussing
the differences in power cords and he showed me the 240 volt cords
they sent to the U.S. He was surprised that I was familar with them.

He also showed me a catalog from a U.S. company called Herbach and Rademan
that sold surplus electronics. He imported items from them. It was
my turn to be surprised, I lived less than 2 miles from them and was
a frequent customer.

By 1989, the store was gone, it had become a Chinese grocery. In 2001 I
was given a stack of U.K. radio magazines and an article about the
store was in one of them. It was written by the nephew of the man
I spoke to. Unfortunatley he had no pictures of the store near the
end, and although I took many photographs of London that trip, I
never thought to take one of the store or his uncle. :-(


Geoff.

 

[Robert Latest]

["Followup-To:" header set to sci.electronics.design.]

There are several kinds depending upon the current rating and if 120
volts is used too. Before 1996, the ground pin was also used for neutral
for things like clothes dryers that had a 120 volt motors and timers and
240 volt heaters. I think that practice was stopped in the late 1970's.

In 1996, it became illegal. If your device has a mixture of 120 and 240
volt components, you need to have a four wire plug. I left the U.S. in
1996, so I've never seen them.

Just to add more aspects to this discussion. In Germany, practically all
houses have 400V three-phase electricity, which is three 230V phases 120°
degrees apart. So all the normal 230V outlets are just a single phase out of
those three plus neutral.

Big appliances in a fixed location like electric ovens and water heaters get
all three phases but are not required to use them in balance.

The nice thing about this is that if you want to set up a workshop in your
house, all you need is some extra fuses and cable and a couple those nice
big, red CEKON sockets.

robert

 

[b]

Done correctly, a quality wire nut is a very secure and long lasting
connection. It's not simply a plastic cap, but a plastic casing over a
threaded springy metal insert which grips the wires very well. I have some
UK terminal blocks, and the problem with them is that there's no mechanical
bond between the wires, the contact point is small, and they can and do work
loose or corrode over time. They generally are ok, but neither method is
greatly superior to the other.

The double current isn't really much of an issue, our large loads are 240V
too, it's handy to have both voltages readily available.

You can get quality US style receptacles, problem is they're expensive so
few houses come with them. I like many things about the UK plugs, but the
thing I don't like is they're *huge* so things like power strips and
multi-gang outlets are really cumbersome.

Having discussed this in length with a friend in the UK, we've both come to
the conclusion that both systems have many advantages and disadvantages and
neither one is a clear winner.- Ocultar texto de la cita -

- Mostrar texto de la cita -

Leaving aside the joining wires/terminal blocks issue, on the subject
of the plugs and sockets, the UK one to me is superior in many ways.
1. fused plugs.
2. cord grip in plugs
3. screw terminals in plugs -no wrapping wires.
4. ALL receptacles and plugs have earth pin.
5. 3 prong design means a better fit (they don't waggle about at all)
6. much thicker pins - handle more current, do not bend, and seem to
resist arcing damage better.
7. switched sockets
......etc.

The US /japan one only has the advantage of compact size, personally I
can live with a bigger plug if it means better performance. I couldn't
care less about cosmetic aspects!

just my tuppence' worth. -B.

 

[Geoffrey S. Mendelson]

Leaving aside the joining wires/terminal blocks issue, on the subject
of the plugs and sockets, the UK one to me is superior in many ways.
1. fused plugs.

Ok, I'll conceed that one, but only 50%, after all, how many people
put a 16amp fuse on a .5mm cord?

2. cord grip in plugs

You can get them in the U.S. I occasionaly use them here for 120
volt equipment (I brought a few items with me) and had a friend
bring me some LEVITON (high quality plugs) from the U.S. They
ave execelent grips on them.

3. screw terminals in plugs -no wrapping wires.

The Leviton plugs have them too. I'm not sure they are an advantage,
the gripping area is the area of the screw shaft,not the circumfrence
times the area of the wire surface, a lot smaller.

4. ALL receptacles and plugs have earth pin.

Cut me a break. Since around 1960 all of the outlets in the U.S. have
grounds. In the U.K. you can buy appliances with 2 condoctor cords
with two plug pins that can usually be forced into U.K. outlets.
They are supposed to be for export to the E.U. but they are sold.

Many of the appliances sold here come that way too, but I must be
the only person who cuts them off and puts three pin plugs with large
grips on them. I also write the name of the appliance on its plug.

It does not make an difference electricaly, the appliances come with
two conductor cords and I don't replace them.

5. 3 prong design means a better fit (they don't waggle about at all)

See above.

6. much thicker pins - handle more current, do not bend, and seem to
resist arcing damage better.

That's a big problem here. Many appliances use 15-16 amps (at 230 volts)
and come with the smaller round plugs which are rated at 16 amps, but
not for continuous duty. When we moved into this appartment, all of the
outlets had burnt "hot" pins because the previous tenants plugged
high current heaters into them.

I replaced the outlet for our oven with an airconditioner plug, which
except for the round pins looks like a U.K. plug. It's no longer
used we replaced it with a gas oven.

7. switched sockets

Maybe. only good if they are not at floor level.

One advantage we have here in Israel is that all new construction
requires a GFI on all outlets. Usually it's BEFORE the main
circuit breaker.

.....etc.

The US /japan one only has the advantage of compact size, personally I
can live with a bigger plug if it means better performance. I couldn't
care less about cosmetic aspects!

As someone said earlier, it depends upon how much you pay. If you
buy cheap junk, you get cheap junk.

Geoff.

 

[Dave Plowman (News)]

Ok, I'll conceed that one, but only 50%, after all, how many people
put a 16amp fuse on a .5mm cord?

13 amp is the largest plug top fuse. And all flex these days is such that
it will blow a 13 amp fuse in event of a short - to allow for the fact
that householders won't use the correct fuse.

You can get them in the U.S. I occasionaly use them here for 120
volt equipment (I brought a few items with me) and had a friend
bring me some LEVITON (high quality plugs) from the U.S. They
ave execelent grips on them.

You've no choice in the UK - all plugs must conform to the BS standard.
One without a cord grip wouldn't.

The Leviton plugs have them too. I'm not sure they are an advantage,
the gripping area is the area of the screw shaft,not the circumfrence
times the area of the wire surface, a lot smaller.

Cut me a break. Since around 1960 all of the outlets in the U.S. have
grounds. In the U.K. you can buy appliances with 2 condoctor cords
with two plug pins that can usually be forced into U.K. outlets.
They are supposed to be for export to the E.U. but they are sold.

No you can't - legally. With the exception of shavers or toothbrushes etc
designed to fit a transformer isolated bathroom outlet, everything must be
fitted with a '13 amp' plug with a suitable fuse.

Many of the appliances sold here come that way too, but I must be
the only person who cuts them off and puts three pin plugs with large
grips on them. I also write the name of the appliance on its plug.

It does not make an difference electricaly, the appliances come with
two conductor cords and I don't replace them.

See above.

That's a big problem here. Many appliances use 15-16 amps (at 230 volts)
and come with the smaller round plugs which are rated at 16 amps, but
not for continuous duty. When we moved into this appartment, all of the
outlets had burnt "hot" pins because the previous tenants plugged
high current heaters into them.

I replaced the outlet for our oven with an airconditioner plug, which
except for the round pins looks like a U.K. plug. It's no longer
used we replaced it with a gas oven.

7. switched sockets

Maybe. only good if they are not at floor level.

Well if you reach down to plug/unplug you can operate a switch at the same
time. Most do as it's sort of bred into them through habit - most outlets
have always been switched in the UK.

One advantage we have here in Israel is that all new construction
requires a GFI on all outlets. Usually it's BEFORE the main
circuit breaker.

The usual modern way here is to have a split load consumer unit. One set
of MCBs protected by an RCD and one set not. The non protected used for
fixed loads like cookers and water heaters where slight leakage might
cause an RCD to trip. But we seem to be moving to one RCBO (RCD and MCB
combined) per circuit.

As someone said earlier, it depends upon how much you pay. If you
buy cheap junk, you get cheap junk.

In general it's not possible to buy poor quality plugs and sockets in the
UK.

This is one example of the bottom end price wise, but will give good
service for years.

http://www.tlc-direct.co.uk/Products/AA213SS.html

Of course you can pay several times that much for chrome etc finish
accessories.

 

[Tim Shoppa]

Most US-style fixtures have some plastic barriers between hot and
neutral and ground. If the wire was stripped too long the barriers
don't help... :-(.

Stranded is the standard for line cords. I've never seen a line cord
with solid copper (maybe forbidden by code?)

I have never seen a house here in the US wired with stranded wire, except
for one built in 1906.

Knob-and-tube was used through the 40's, maybe even 50's, in some
places in the US, and in most places is still allowed for repairs and
even extensions (if you can find the stuff! And no inspector ever
agrees with anyone on how to extend knob-and-tube using Romex!)

Generally #14 solid copper.

Where Romex is allowed, you're right. But there are some localities
where even residences have to be wired with conduit and there the ease
of pulling stranded outweighs the slightly increased cost for the
stranded for a lot of runs.

Tim.

 

[N Cook]

["Followup-To:" header set to sci.electronics.design.]

There are several kinds depending upon the current rating and if 120
volts is used too. Before 1996, the ground pin was also used for neutral
for things like clothes dryers that had a 120 volt motors and timers and
240 volt heaters. I think that practice was stopped in the late 1970's.

In 1996, it became illegal. If your device has a mixture of 120 and 240
volt components, you need to have a four wire plug. I left the U.S. in
1996, so I've never seen them.

Just to add more aspects to this discussion. In Germany, practically all
houses have 400V three-phase electricity, which is three 230V phases 120°
degrees apart. So all the normal 230V outlets are just a single phase out of
those three plus neutral.

Big appliances in a fixed location like electric ovens and water heaters get
all three phases but are not required to use them in balance.

The nice thing about this is that if you want to set up a workshop in your
house, all you need is some extra fuses and cable and a couple those nice
big, red CEKON sockets.

robert

When I was in the local reference library today I looked up when the last
Southampton, England house was converted from DC to the new-fangled 240V ac.
It was 28 September 1967

 

[Tam/WB2TT]

Could someone direct me to pics of the 2 different types of plug/socket
system used in the USA to differentiate for medium and high power use, I
didn't even realise 220 or 240V was used residentially anywhere in the
USA.

Electric clothes dryer, stoves/ovens, and permanently installed air
conditioners are only available in 240 V versions. Also, larger sizes of
electric space heaters. The first three are probably more likely to be wired
in directly to a junction box than to use a plug/socket. There are several
incompatible types of 240 V plugs. All are huge, bigger than the UK plug,
and expensive.
Tam

 

[Joel Kolstad]

Where Romex is allowed, you're right. But there are some localities
where even residences have to be wired with conduit...

Really! I'm amazed... I thought Romex really had taken over the country
completely... does some locality think Romex is dangerous? Or they just
haven't updated their electrical codes to take it into account?

Hey, Louisiana was the last state to finally outlaw cock fights, doing so...
today. Hmm...

 

[[email protected]]

Have you seen the way they connect their wires? They just twist them
together and put a plastic cap over the bare wires!
Multiply that by double current and it's no wonder they have fires -

Well, much of the "fires" due to faulty wiring are because we have
*had* wiring as a general condition in most houses since the early
1900s, so after 100 years or so it gets a little tired, and when
overloaded can fail. Of course, 100 years ago, y'all had very nice
green lawns and gorgeous buildings.... but little electricity other
than the very wealthy. Other fires are due to just plain idiocy on the
part of users, such that would occur here, there or anywhere else.
Very damned few fires are caused by properly utilized wiring even if
100 years old.

As to wire-nuts, what would you propose? Per the code, they must be
enclosed, the expectation is that the wires are first twisted
together, then the nut is attached, and the internal threaded section
is spring-loaded. Are you seriously telling me that wire-nuts are not
permitted in your country?

De gustibus non est disputandum. Electricity has been working for us
over here a good deal longer than it has been working for you over
there. The typical poor-man's rowhouse (900 sf, 100 sm) in
Philadelphia has been wired since 1913. Parts of NYC have been wired
since the late 1800s...

On the other hand, there is something to be said for observing the
experiences of others for 50 years or so before taking the plunge...
Cell phones are a similar item. The US started Analog, only slowly
went digital because of legacy issues, Europe dropped the first nearly
10 years of teething, the Middle East and third-world went right to
Tri-band....

Peter Wieck
Wyncote, PA

 

[Dave Plowman (News)]

Well, much of the "fires" due to faulty wiring are because we have
*had* wiring as a general condition in most houses since the early
1900s, so after 100 years or so it gets a little tired, and when
overloaded can fail. Of course, 100 years ago, y'all had very nice
green lawns and gorgeous buildings.... but little electricity other
than the very wealthy.

You're not saying there is 100 year old wiring still in use?

 

[Geoffrey S. Mendelson]

De gustibus non est disputandum. Electricity has been working for us
over here a good deal longer than it has been working for you over
there. The typical poor-man's rowhouse (900 sf, 100 sm) in
Philadelphia has been wired since 1913. Parts of NYC have been wired
since the late 1800s...

My "rich man's" rowhouse built in 1916 in Philly, which was quite deteriorated
by 1975 when I moved in had a meterboard marked "Philadelphia Electric
Company 1925" on it. I call it a "rich man's" house because it
was 1200 square feet, had a basement, hardwood floors and
some expensive (at the time) finishing touches.

When I moved in it had 25 amp 240 volt service with a four circuit fuse box.
I upgraded it to a 16 circuit fusebox and later had the whole thing replaced
with 200 amp service.

To follow the Philly theme, Willingboro, New Jersey (originaly Levittown)
houses were wired with aluminum wire because of a copper miner's stike in
South America. By the 1970's the wires broke inside the walls, arced over
and caught fire.

Geoff.

 

[Geoffrey S. Mendelson]

Dave Plowman (News) wrote:

You're not saying there is 100 year old wiring still in use?

No, he IS saying it is in use. Some of it has been replaced, but not
all of it.

Geoff.

 

[Dave Plowman (News)]

No, he IS saying it is in use. Some of it has been replaced, but not
all of it.

I'm amazed. It presumably has some form of rubber insulation which will
have crumbled away years ago.

 

[Charlie Edmondson]

No, he IS saying it is in use. Some of it has been replaced, but not
all of it.

I'm amazed. It presumably has some form of rubber insulation which will
have crumbled away years ago.
[/QUOTE]
More likely cloth, not rubber...

Charlie

 

[[email protected]]

I think there is an inherent safety factor in a system where neither side of
a 240V circuit is more than 120 V above earth potential. Never heard of a
person being electrocuted who was not standing, or otherwise submerged, in
water. This costs money.

Its a known deal that 240v is safer than 120 for 2 main reasons.
1. The main killer is not electrocution, it is fire.
2. 240v gives much better discrimination between normal and fault
loads. IOW faults have less chance of tripping a breaker in time on
120v circuits.


NT

 

[Tam/WB2TT]

More likely cloth, not rubber...

Charlie

As late as about 1980, my father in law's house still had some original ca
1906 wiring. It was cloth over rubber, like telephone wire. In fact, it
probably was. Part of the house had been rewired so you could use a hair
dryer or clothes iron. Fuses were short pieces of bare small gage wire
between two terminals. You had to turn off the main power switch (It had a
big handle) to change a "fuse". I hope the new owner did some electrical
work.

Tam

 

[[email protected]]

b wrote:

Ok, I'll conceed that one, but only 50%, after all, how many people
put a 16amp fuse on a .5mm cord?

There are 2 main advantages to fused plugs.

1. When an appliance has its own fuse, a faulty appliance disables
itself. With unfused plugs that most countries use, someone can and
likely will plug the faulty appliance into another socket at some
point, and be exposed to the danger again, possibly several times as
it changes hands.

2. The fuse only need be rated to supply the appliance, so most
protective fuses will thus be of much lower current rating (typ 3A)
than they would be on unfused plug circuits. This improves
discrimination greatly, helping to ensure more faults are cleared
quickly and safely.

You can get them in the U.S. I occasionaly use them here for 120
volt equipment (I brought a few items with me) and had a friend
bring me some LEVITON (high quality plugs) from the U.S. They
ave execelent grips on them.

Many plugs not having them means lots of damaged and failed
connections due to repeated movement and strain. Sale of gripless
plugs has been illegal here since the early 70s.

I used to use gripless plugs years ago, and all the bad connections,
wires coming out and most-strand-broken conductors that happened then
are rarely seen with today's gripped plugs.

The Leviton plugs have them too. I'm not sure they are an advantage,
the gripping area is the area of the screw shaft,not the circumfrence
times the area of the wire surface, a lot smaller.

What happens is the copper flex deforms to fit the connector and
screw. Having used both modern connectors and old wraparounds, the
modern one is much more reliable. The greater contact area of
wraparounds is of no benefit in practice, screws provide more than
enough contact area.

Cut me a break. Since around 1960 all of the outlets in the U.S. have
grounds.

I'd agree with you there, and hope 2 pin UK plugs become permitted one
day, probably only premoulded ones on appliances to stop their misuse.

However when 2 pin rewirable plugs are sold it is inevitable some will
be misused on 3 core leads.

In the U.K. you can buy appliances with 2 condoctor cords
with two plug pins

not legal here.

that can usually be forced into U.K. outlets.
They are supposed to be for export to the E.U. but they are sold.

The only time EU 2 pin plugs are sold on appliances is when a UK
adaptor is permanently attached to the 2 pin plug, bringing it up to
UK standards. These are seen now and then on imported goods that were
orignally intended for the (non-UK) european market.

Also there are 2 very similar types of 2 pin plug which sometimes
causes confusion. The modern EU ones cant fit a UK socket, the pins
are too fat and too closely spaced. Forcing doesnt work. There are
also historic French plugs that look similar and do fit our sockets
with a bit of fiddling, but very rarely does one see one of those used
over here. They have 4mm pins. I dont think I've seen one in over 20
years.

See above.

waggly sockets are unheard of here, but common in US.

Maybe. only good if they are not at floor level.

Means goods are switched safely rather than by pulling the lead out,
which damages socket contacts by arcing, leading to overheating and
fire.
Also means many appliances and cords arent left live when not in use.
Most UK sockets are switched, though not all.

We have a bit of an issue with socket positions here. The great
majority of sockets are low down, and this doesn't stop the switches
being used. However new builds now require them high up for dubious PC
reasons, transforming trailing leads into trip hazards, which I think
will only cause more injuries and electrical faults.

As someone said earlier, it depends upon how much you pay. If you
buy cheap junk, you get cheap junk.

....which naturally dominates a price-led market. A political issue
AIUI.

Here our cheapest stuff has 3 solid pins, half insulated pins,
cordgrips, shutters, screw connections on plugs and all sockets, and
is normally solid reliable equipment.

It seems to be political why the US doesn't want to stop the sale of
unsafe accessories and the deaths that result.


NT

 

[b]

Here our cheapest stuff has 3 solid pins, half insulated pins,
cordgrips, shutters, screw connections on plugs and all sockets, and
is normally solid reliable equipment.

It seems to be political why the US doesn't want to stop the sale of
unsafe accessories and the deaths that result.

NT

a clear example of what market forces dictate in fact NOT being for
the general good.

laissez-faire capitalism - what do you expect! ;-)

-b.