Internal wiring of USA v UK mains plug

Seems the US developed a long lasting wiring system long before we did. It wasnt until ashathene and pvc cables in the 60s that we finally got cables of types that would truly last long term. So old wiring here is almost invariably highly risky, in a very bad way and only very occasionally encountered at all.

The main old types here are

- cotton/rubber, and its normal for the insulation to have perished and fallen off in places, and not just at the ends.

- lead sheathed rubber insulated from 1930s, the ends of which get into a state.

NT

I dont see how. Cooking fire risks certainly differ by socio-economic group, but I dont think electrical fire risks vary much. Things are perhaps different in the US.

20mA is the typical figure for our standard 30mA RCDs, but most fire causing faults are not detected by RCD, and most properties dont have an RCD.

But that is a separate issue to fault current discriminaiton.

NT

That is just the half-of-it. We have had NEMA (National Electrical Manufacturers Association) standards for pretty much all of present living memory such that appliances (AC & AC/DC) manufactured in the

20s are compatible with receptacles and ratings today. For instance, 1920s-installed duplex receptacles will accept fat-blade neutral (polarized) plugs that are today's standard. One can 'call out' by NEMA number a receptacle and plug that are specific to, and compatible with both the load and application, from isolated-ground hospital- applications to heavy-load vibration-proof applications, one, two (yes, there is still 4-wire/2-phase power applications in the US) and three-phase. And, be assured that that unit and/or combination will fit and be acceptable anywhere in the US. One example I claim is a 1928-model Sky Rover radio with a tri-voltage switchable power-supply (105/110/120V) and a standard NEMA-labeled plug. About a year-and-some after NEMA's inception.

On a related note, IMAGINE purchasing an appliance with no plug on it... on the premise that what is in your house is not the same as next door, or next door to that. AND THEN... the home-owner is expected to purchase said plug compatible with their specific system, THEN to install it correctly. This was the common state of affairs in parts of Europe until not so long ago.

Fascinating also that every country in Europe seems to have a different standard for receptacles, wiring, fusing and so forth. Y'all do need standards if only to allow cross-border commerce much less reduce costs and enhance safety.

Peter Wieck Wyncote, PA

Actually, this is common in USA woodworking equipment also. Many of my 240V machines came with no plug.

With no plug, or no cord at all? Those are two entirely different things. The former is illegal, the latter quite common. With the latter, there will be a note: Professional Installation Only or words to that effect.

Peter Wieck Wyncote, PA

I've seen both "cord with no plug" and "no cord at all". The reason is usually that the tool can be internally wired for either 120v or

240v, and which you choose determines which plug you must install.

I'm not talking about hand tools, I'm talking about big cast iron tools like table saws and jointers.

We have the NEC, ANSI (and NFPA) and NEMA. That is:

National Electrical Code

American National Standards Institute

National Fire Protection Association

National Electrical Standards Association

They all have jurisdiction over the way things-electrical are represented, sold, wired and fused. We have a National testing organization - Underwriter's Laboratory, AKA UL that puts labels on entire assemblies (UL) or parts that go into them (UR), and works closely with Canada in the same way with similar alphabet soup.

Our receptacles have very narrow slots with the conductors held back from the front. Not at all to say that accidents don't happen, but it is not so easy as with the honking-large slots on Brit receptacles so, putting little shutters on them is a good idea.

Peter Wieck Wyncote, PA

snipped-for-privacy@care2.com wrote in news:1183141239.957620.211930 @q69g2000hsb.googlegroups.com:

The way I see it:

The lower classes see thmselves more as DIYers, even if they are bad at it. The lower classes generally cannot afford to have out of date electrical upgraded to modern standards, so try to bodge what they have to something they feel is useable, sometimes with disasterous results.

"N Cook" wrote in news:f62e5g$174$ snipped-for-privacy@inews.gazeta.pl:

They are named with a spec code that electricians learn, which is pretty simple (first digit pertains to the voltage/terminals, the second amperage).

Not like BS and CEE numbers which directly mean nothing, although I think one could boil those 30 down to about 5.

There's about 3 different types of receptacles you'll find in a US residence, the rest on that list are either industrial stuff or obsolete things you might find in the occasional 1950s or earlier house. Generally you'll find mostly 15A 120V grounded types, then the clothes dryer will have a 30A 240V receptacle and the kitchen stove will have a 50A 240V receptacle. Other high powered items like an electric furnace, water heater, spa, etc will be hard wired. Sometimes you'll find a 15 or 20A 240V receptacle in the garage for something like an air compressor or small arc welder but these are generally added by the homeowner. It's really not very complicated.

I know the UK has a number of plugs and receptacles in the same category, I've got a small pile of various oddballs from over there right here.

GFCIs have been mandatory here for decades on any receptacle located outdoors or within a certain distance of water, such as in kitchens and bathrooms. Modern code is now requiring arc fault interruptors in bedrooms, and eventually everywhere.

Not really. In a domestic environment anything that can't be plugged into a 13 amp outlet will be hard wired. Including cookers, water heaters, showers, etc. A very posh home workshop may use BS 4343 industrial types though as some machine tools on single phase may need more than 13 amps. Three phase domestic supplies are pretty unusual.

--
*A closed mouth gathers no feet.*

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

Well that's not much different than here, only difference I see is that we have 30 and 50A 240V plugs to allow cook stoves and clothes dryers to be high power yet not hard wired. Standard clothes dryer here is 4KW, kitchen range is 12KW. I had a Creda dryer for a while from the UK, it was a nice unit, but tiny and took forever to dry.

Looking through the box here... There's an IP44 plug, not even sure what it's for, but I've never seen anything like it, looks very heavy duty, a round pin 2 amp plug that says it's for table lamps which oddly enough has three prongs just like the big clunky plugs, got a few of those, hmm, could swear I had another type as well.

I like the quality of the parts overall, but these junction boxes are

*teeny*, it must be a real pain to wire them. I like the BC light sockets as well, though they don't hold large heavy bulbs very straight.

There are also outlets used for room air conditioners. I have a 120V

15/20A outlet by one window downstairs and a 240V 20A (IIRC) outlet for the thru-the-wall AC. Stoves and clothes dryers may also have either a three pin ungrounded or four pin grounded outlet.

--
  Keith

I've heard of those, I don't recall ever actually seeing a 240V window AC unit though. AC in general is very rare around here and if people have it, it's normally central. Perhaps 0.1% of the houses have vertical casement windows that an AC unit will fit in, I suppose that would explain it.

Right, things are different here then (UK). Its mostly the upper class with grand buildings that keep running historic installations. The less wealthy usually rent rather than own, and laws are much more stringent than those applying to privately owned dwellings. Capitalism backwards.

NT

I have (vertical) "casement" windows that are difficult to find window units for (even uglier to install). I also have two "window" units installed through the wall. One is a 25KBTU unit on a 240V 20A circuit, IIRC. The other is 7.5KBTU on a normal 120V 20A (15A outlet) circuit.

We normally only have two weeks of weather where an AC us useful (mine have run a total of 20 hours so far this year) so central AC is a bit expensive.

--
  Keith

240-volt, single-phase plugin window-mount a/c units are very common in the US south, in older homes. They are nearly essential to survival.

John

My previous house, a Victorian built in 1892, had gas pipes leading to all the lighting fixtures, capped off, and exposed knob-and-tube wiring in the attic. Junctions were twisted and taped, hanging in mid-air. I assume the original wiring was intended for lighting, and over the years, as more loads were added, it became less suited. I had a few joints open up, and eventually rewired it with Romex, with all joints inside proper metal junction boxes. There's still a lot of ancient fabric-insulated, twisted-junction knob-and-tube stuff around.

It's common to see a fuse box, designed for 5 or 10-amp screw-in fuses, to be full of 30's.

Around here, knob-and-tube was succeded by mandatory rigid steel conduit and later, roughly 1960 maybe, Romex. Commercial buildings must still use conduit, rigid metal pipe or the flexible MX stuff. There is no requirement that old construction be upgraded, unless a major remodel is done.

John