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Re: Internal wiring of USA v UK mains plug

G

Geoffrey S. Mendelson

Jan 1, 1970
0
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.
 
G

Geoffrey S. Mendelson

Jan 1, 1970
0
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.
 
D

Dave Plowman (News)

Jan 1, 1970
0
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.
 
C

Charlie Edmondson

Jan 1, 1970
0
Dave said:
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
 
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
 
T

Tam/WB2TT

Jan 1, 1970
0
Charlie Edmondson said:
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
 
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

b

Jan 1, 1970
0
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.
 
R

Richard The Dreaded Libertarian

Jan 1, 1970
0
Sounds dodgy!
I've spent time in the US and Japan, and I have to say that those flat
blade sockets are an atrocious design. They suffer sloppy fit problems
very easily . Those countries don't seem to have switched wall sockets
either, which the Uk standard has, so you get more arcing if plugging
in live equipment

In the US, we know better than to do stupid crap like plugging in live
equipment.

Good Luck!
Rich
 
E

Eeyore

Jan 1, 1970
0
Geoffrey S. Mendelson said:
Ok, I'll conceed that one, but only 50%, after all, how many people
put a 16amp fuse on a .5mm cord?

No-one these days. A lamp for example will come with a plug already fitted and
probably a 3 or 5 amp fuse in the plug.

Graham
 
E

Eeyore

Jan 1, 1970
0
Geoffrey S. Mendelson said:
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.

You can only force them into UK sockets with the aid of a large screwdriver down
the earth to open up the shutters. You're not supposed to do that.

The neat answer if you want to continue to be able to use them abroad is to use
one of these.

http://i17.ebayimg.com/04/i/07/20/fb/ag_1_b.JPG
http://cgi.ebay.co.uk/EURO-CONVERTO...ryZ96942QQrdZ1QQcmdZViewItem#ebayphotohosting

Graham
 
R

Richard The Dreaded Libertarian

Jan 1, 1970
0
It seems to be political why the US doesn't want to stop the sale of
unsafe accessories and the deaths that result.


Yes. Entirely political. We are the Land of the Free. If people want to
electrocute themselves, they have that right. Most of us in America are
grownups, who know better, and so don't need nanny queen to wipe our ass
for us.

Thanks,
Rich
 
E

Eeyore

Jan 1, 1970
0
Tam/WB2TT said:
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.

Considering that the UK plug is good for 3kW, it's not really that large.

Graham
 
E

Eeyore

Jan 1, 1970
0
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.

I'd like to see some supporting data for that litle outburst.

Graham
 
E

Eeyore

Jan 1, 1970
0
Dave Plowman (News) said:
I'm amazed. It presumably has some form of rubber insulation which will
have crumbled away years ago.

There's still some remnants of old rubber insulated wire in my house. It's in
quite good condition actually.

I imagine the current PVC stuff must be about 40-50 yrs old.

Graham
 
E

Eeyore

Jan 1, 1970
0
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.

Required ?

Since when was this . As you say, it seems to be a daft idea.

Graham
 
T

Tam/WB2TT

Jan 1, 1970
0
Its a known deal that 240v is safer than 120 for 2 main reasons.
1. The main killer is not electrocution, it is fire.

That is a sociologic/economic. not technical issue.

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.
I don't know what your load is. The US load per branch circuit is 1800 W,
before the circuit breaker in the box will trip. I think a GFI will trip at
10 microamps.

Tam
 
G

Gary Tait

Jan 1, 1970
0
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.

http://nooutage.com/nema_configurations.htm

Some are used only in industrial and commercial situations though.

Not shown is the NEMA 10-xx configuration, which is used for the
aformentioned 120/240V appliances that use a neutral for chassis grounding
and as a return for internal 120V loads. They basically have angled hot
prongs with a straight or L shaped neutral prong (appropriately sized for
the load). FWIW, the NEMA 10-15 plug is exactly the same as a typical
Australian plug, less safety features.
 
D

Dave Plowman (News)

Jan 1, 1970
0
More likely cloth, not rubber...

If like UK wiring of that age, rubberised cloth. Which crumbles away. Uk
wiring was often lead sheathed and inside the sheath the insulation can be
perfect. But the ends exposed to air etc not.
 
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