For residential electrical use, there are two basic voltage & AC
frequency systems across the world, http://kropla.com/electric2.htm .
Does one have an advantage over the other? In other words, if you were
starting from scratch and could impose a world standard, what would you
What voltage and what frequency?
Transmission wasn't mentioned only what power would be best for houses.
You can do some nice stuff if you have a higher frequency supply than
Like controlling motors is easier, transformers are smaller, SMPS are
I'm not convinced that it would be worse for distribution either, but you
probably want a ~2kV - 100V ferrite transformer near the home.
Agreed-partially. While 400Hz requires less iron in a motor, the problem
is that, for the speeds of typical household motors, we are looking at much
higher synchronous speeds- many more poles. Possibly a large diameter
pancake or simply use "brushless DC". Same control problem with that as with
a 60Hz supply. Transmission at 400Hz has its problems anywhere where
distances are large or L and C are appreciable. so that at local
substations there would have to be frequency converter stations- not cheap.
May as well go half-way and go DC for less$$.
Now, 480V, 3 phase, sounds good at either 50 or 60Hz.
C'mon now, APL isn't that bad to read unless you want to show off with
recursive one-liners! At least one can concentrate on the problem rather
than the code.
Why? What advantage?
400Hz is useful for aircraft because of weight/volume/power considerations
but these don't apply. Also 400Hz in home would require frequency converters
(extra $$$) as distribution is not particularly practical at this frequency
in comparison to 60Hz or below.
As for 100V, again why? What gain is made?
The proper answer to the original question is "it depends"
Generally, higher voltage is good, because it carries a lower current for
the given power. Of course, higher voltage also increases the possiblity of
arcing (IIRC, I was a mechanic, not an electrician), so a balance needs to
be struck. I say go with 450V.
As regards voltage 230 ever time. Permits effective high powered small
appliances, kettles etc.
The Americans wire 110-0-110 ("0) into fixed appliances such as
stoves and aircon.
110v has no electrical shock safety advantage over 220/230v. If it
would not be safe at 220v, it could not be relied on to be safe at
The 230v standard does have significantly lower fire risk, (half the
current for the same power).
A typical American wooden built house with aluminium wiring and 110
volts = "Giant Firework"
As regards frequency there's not much in it. Iron losses in
transformers increase with frequency., but fluorescent Tubes flicker
less at 60Hz (however increasingly nowadays fluorescent tube ballast
are high frequency solid state devices, so this wouldn't then count).
Similarly TV's scanning at 60Hz, but AFAIK since colour they are not
mains locked any more, but they probably don't move that far away from
the local mains freq. to avoid mains intereference running through the
picture. Refreshing the pictures at 60Hz uses 20% more bandwidth than
50Hz, hence the American 525 line standard and our 625lines.
The North American system has the advantage that both 120 and 240 volt
circuits are available for both fixed and portable appliances. One
sees the 240 volt outlets mostly in workshops, farms (for heavy duty
electric heaters, or for commecial installations (restaurant
applicances, for example). 240 volt circuits are common for air
conditioners, dryers, electric ovens, and water well pumps and
heavy-duty power tools.
Some Brits are fond of saying that, with our system, we who live in
North America can't operate that power hungry deep fat fryer in our
kitchens with our wimpy 120 volt appliance circuits. The truth is we
seldom miss it. A deluxe kitchen can easily be constructed with a 240
V. outlet for commerical kitchen appliances, if desired.
All American kitchens are required to have at least two 20A 120 volt
appliance circuits for a total of (at least) 4800 watts available.
These seems to do a good job powering the toasters, microwave ovens,
mixers, can openers, and electric grills that are commonly used.
Also, when the design calls for more power, an additional circuit is
Probably the biggest safety advantage of the North American system is
that in no room of any house is there a conductor with greater than
125 volts potential to earth ground (even though 240 volts is
available where required). This applies to kitchens, bedrooms,
bathrooms, hot tubs, garages...everywhere.
In theory yes... but if you've actually been the recipient of a shock
at 220 - 230 volt, it is comparatively more painful, (and more
difficult to let go of) than 110-120 v.
If what you are saying were true, there would be no need for the 50 -
0 - 50 volt scheme that is used for UK power tools on construction
sites. ... If there are 240 V. appliances... why not 240 V. power
tools? There is a reason for this.
In contrast, modern 120 v. power tools are considered electrically
safe in North America. (This was not always the case before universal
grounding, double insulation, and the requirement for GFCI
(differential) circuit protectors).
There is a tradeoff between voltage and current. The downside of the
higher voltage is that insulation requirements are higher and the
physical spacing between two conductors at devices such as a plug must
be greater (hence the device must be physically larger).
I like the design of the Shuko plug and receptacle. It seems safe and
is well designed for a 230 volt circuit. It's just not very elegant
when you put them in a power strip, for example. The whole thing is
just too big.
Also, speaking of fire risk... Because of the comparative difficulty
of making low wattage incandescent light filaments at 240 volts, these
lamps tend to run a super hot temperatures (when compared to
equivalent 120 volt incandescent lamps with a similar light output).
I'm sure that the UK is well on its way to converting to compact
fluorescents, but I'm also sure that many of these super hot
incandescents are still in use.
Aluminum (same element -different spelling) wire for US residential
branch ciruits has not been used for decades. It was recognized as a
problem and there have have been wiring techniques developed to make
retrofit installations safer.
Aluminum and Aluminum alloys are commonly used for service entrance
cable and are even considered to be safer than copper. In the event
of a rare, direct short, the aluminum cable will eventually melt and
break the current. The copper is likely to get insanely hot, but keep
the current flowing for a much longer time- so I'm told.
50 Hz flicker is visible in low wattage incandescent bulbs. The
filament just cools too fast. This is one of the reasons the higher
60 Hz frequency was chosen for the North American System.
TV's require precisely locked oscillators, which were difficult to
design and stablize in the 1940's and 1950's, hence, the TV's of the
time were locked to the local line frequency. This represented the
most accurate time base of the time.
Oscillators got better and more stable with the introduction of solid
state circuits and crystals. No modern TV need to use the power line
for an external time base reference.
The Germans wire 3-phase into heavy appliances - like instant showers in
The British system has the advantage that we don't need separate circuits.
Yes, but you still can't use a decent kettle in the bedroom.
Yes, it's because 50V has a safety advantage over both 110 and 240V. 50V
is *Extra* low voltage. Anyway, 50-0-50V pre-dates RCDs and isn't
actually necessary now, although most sites still insist on it.
A lot of things are considered safe in North America that aren't here,
like wire nuts and sockets in bathrooms.
The presence of 2 voltages is a disadvantage, because it restricts what
can be plugged in where, and increases the amount of wiring required.
Everything on 240 makes better sense. We used to have a 4 plug system,
with 2A 5A and 15A 3 pin plugs, plus 5A 2 pins. What a horror it was: a
single universal socket is a significant advantage.
all ours have 3kW outlets, theyre universal, no extra cost.
I'm surprised, I though you were a real power hungry nation. We have at
least one 30A 240v circuit in every kitchen, 7.2kW.
IRL its not a safety advantage. People think they can get away with
things they wouldnt dare do here, and the result is more deaths, not
less. Our system is specced to (mostly) higher safety standards partly
because it needs to be. 240 is not to be messed with, and everyone
yes, hence the differing attitudes towards it. The US routinely does
various things with electrics that are illegal here on safety grounds.
There is no need for 55-0-55 onsite, we do use 240v tools onsite. 110v
tools are a historic thing. With RCDs we no longer worry about using
240v on a wet site so much, whereas before RCDs, in wet conditions, it
was a clear risk - as of course 110 would be, though less. Hence we
went with 55v.
I'm not sure thats a downside, really it depends on your material
resources as to what voltage cable is most economical. IIUC America has
a lot more copper availability than here, so we spend more on the
plastic and less on the copper. Fwiw a century ago copper cable was
considered excessively expensive, and steel cable was sometimes used.
Steel makes truly bad cable, illustrating the high cost of copper.
larger spacing is needed, but its not a downside in any way.
no, not at all. The spacings involved are small compared with plugtop
sizes, it really makes no difference to plug size. Our huge plugs are a
British oddity I would definitely not repeat if starting from scratch.
IEC plugs/sockets might be good if they were metal sleeved, using the
sleeve to connect earth.
Our plugs seem to be an oddity of history. At least theyre a bit better
than the South African plug, which is the one we quit using half a
century ago. But the US ones are very poorly specced, a recipe for
I'd like to see a 2 pin version of our square pin plugs. Compatible,
cheap, space saving, material and energy saving.
no no. Higher R requirement means a thinner filament, and this is run
at lower temp to slow down evaporation, as there isnt much to
evaporate. The filament runs cooler: this has insignificant bearing on
the temperature of the glass bulb. This is only an issue for 25w and
15w bulbs, the higher wattage ones perform better.
110v is closer to the ideal efficacy voltage for house bulbs. But of
course there are better solutions.
In a short a fuse would blow. If it ever gets to the stage where the
incoming cable melts, the system design has failed badly, and was a
duff design. IRL this isnt a significant failure mode.
Ali expands and contracts, loosening connections. Then when its not gas
tight it oxidises. The resulting resistance produces heat and more
oxidation... your ali supplies are not an advantage. We still have
incomers that are near a century old, with PBJ etc insulation.
The real difference with frequency is the enormous tonnage of iron used
in transformers, ballasts and motors. 60Hz is definitely better than
50, and 100 better again. Theres a tradeoff because higher frequencies
reduce the maximum service area, which causes problems for the power
cos. Also very much higher f and laminated transformers would become
too lossy. Increasing f, upto a point, would reduce the size and losses
of transformers, motors, and ballasts.
IIUC the US got 525 lines in the 50s, we got 625 in the 60s, as much
down to technical progress as anything. Same with the colour system,
PAL is much better than NTSC, because we waited longer before
I think this is a myth. The main oscs in a tv are line and frame.
(There are also rf, psu and colour oscs.) Line oscs have always been
synched to the received signal, first by hard locked sync, later by
flywheel sync. Frame scans have always been locked to received signal
too. Initially the last line on the frame was 1.5 lines long, and the
field scan locked to this. This was changed to work with the much
better flywheel system, all lines became the same length, the frame osc
had to lock to the differing sync pulses.
The reason to keep frame rate and mains freq locked _at the tx end_ is
to avoid noticing the frequency difference ripple moving the picture
about, which is liable to happen on old kit, and looks rather bad. A
fixed distortion OTOH is hardly noticeable, especially on early sets
that were inherently much more geometrically distorted than modern
flatter CRTs. There has never been power line lock at the receiving
end, not with 405 or 625 lines. Perhaps it got implemented on the
earlier 30 line mechanical system, whch was otherwise syncless.
You said later in your post and I quote "110v is closer to the ideal
efficacy voltage for house bulbs" so that is at least one reason for
having the lower voltage. Not all the world has gone over to compact
fluorescents and there are some applications where they might be
I have already argued that safety is another reason.
The North American Codes specify that no point on the kitchen counter
should be less than 3 ft. from an outlet. In my small modest 15 x 15
kitchen I count no less than 9 duplex outlets (18 outlets total).
Our codes are concerned with safety, not convenience, but in this
case, the idea is not to be plugging toasters and other high current
appliance into extension cords. You can't even buy a toaster in the
US anymore with a cord longer than 3 feet. Ever see those movies
from the thirties were the appliances were plugged into the pendant
socket hanging from the ceiling? Apparently, that was real bad...
We are not necessarily power hungry, but there are lots of appliances
that may not necessarily be in use at the same time in a modern
kitchen. The requirement for at least two 20A circuits and the
requirement for many outlets serve the need.
I will conceed that those ring main circuits do allow you to power
that 7.2 kW deep fryer though.... Something we can't do without extra
The most bizarre Euro power setup I ever saw was in the apartment I
rented in Paris about 10 years ago. That French "Disjouncter" or
whatever they call it would ration the power to the point where I
could not have my water heater working if certain other routine loads
where online at the same time. This was true even though the total
load was much less than the installed capacity. They just didn't want
you to be using too much power.
It reminded me of the episode of the American TV Series Green Acres
called "You can't plug in a 6 with a 2". Farmer Douglas tried to
explain to his wife Lisa that all the power cords for the kitchen
appliances had numbers on them corresponding to the size and current
consumption of the device. If you went over 7, the generator outside
the farm would start on fire.
I stand by my original statement. We don't have many people in the US
that say, "Gee it's only 120 volts... I don't respect it". Some...
but not many.
120 volts is safer than 220V. just as 220V is safer than 480V.
The same could be said for some of the UK practices from what I've
Whether it's 120V or 240V, the N.A. codes say that we don't put these
voltages in the shower. We don't even go near 240 volts in the
bathroom. Other than lighting and a bathroom heater, there is only
one allowed a GFCI protected outlet by the sink for a shaver or hair
dryer. Some homes have electric outlets by the toilet. That is if
you have one of those fancy TOTO models that sprays warm water up your
But because you use radial circuits with unfused plugs, you have to have
limits on the number of sockets on a circuit, and thus a large number of
We can have unlimited sockets on a 32A ring (or radial) circuit, subject
to floor area and anticipated load. Our Wiring Regulations don't specify
the minutiae of where to put sockets on a kitchen counter; that's left
to the designer to ensure the installation is adequate.
Of course, the superiority of the British ring circuit is another topic
Same here; the requirement for flexible cords to be short enough that a
a 20A breaker provides adequate fault protection is thanks to European
Actually, we can't either. Individual appliances are limited to 13A (the
fused plug rating).
You can, but not for use on 32A ring circuits using BS1636 13A fused
plugs. The BS4343 unfused plugs (for various voltages and currents) are
for use on application-specific circuits. Connecting such a socket to a
32A ring circuit would present an unacceptably high point load on the
ring, upset the principle of diversity, and possibly mean that an
appliance was insufficiently protected by the circuit MCB.
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