As much as I consider it totally unnecessary, I can't help thinking that eventually Britain will switch to metric speed limits on the roads.

If and when that happens, has anybody considered what will happen to car speedometers? At present, I believe the vehicle regulations specify that cars must have a working speedometer calibrated in miles per hour. Presumably after any change to km/h the rules will require a speedometer so calibrated.

Although this will not be a problem for new cars which have had dual scales for years, I wonder what provision the government will make for veteran and vintage car enthusiasts whose vehicles have only a MPH speedo.

Will they make an exemption for existing vehicles, or are we likely to see an enforced "You must have a km/h speedo no matter what" attitude?

I imagine it will be fudged as usual.

In the past, very few, if any regulations that apply to private cars are retrospective.

Very few cars are involved and the owners of those cars will have to do what the drivers in South Africa and Australia did - memorise the coversions! I did just that in 1973.

Martin: "memorise the coversions!"

...which can't be that difficult, since there are only 4 to 5 numbers to memorise.

re (Paul EOS): "As much as I consider it totally unnecessary, I can't help thinking that eventually Britain will switch to metric speed limits on the roads.

"If and when that happens, has anybody considered what will happen to car speedometers? At present, I believe the vehicle regulations specify that cars must have a working speedometer calibrated in miles per hour. Presumably after any change to km/h the rules will require a speedometer so calibrated.

"Although this will not be a problem for new cars which have had dual scales for years, I wonder what provision the government will make for veteran and vintage car enthusiasts whose vehicles have only a MPH speedo.

"Will they make an exemption for existing vehicles, or are we likely to see an enforced "You must have a km/h speedo no matter what" attitude?"

--------------------------------------------------------------------------------------------------------------

REPLY: You can watch this amazing process actually happening in the Irish Republic at the moment. What a mess! And what cost!

The first phase of metrication was to convert distances in miles on road signs to metric road distances on all the main roads. All the minor roads were left in miles. Result: drive from A to B along Irish roads and the distance keeps on going up and down like a yo yo! Most amusing!

Regulations now require car speedos in Ireland to lead in kilometres, with miles per hour as secondary. It'll be a headache for all those with lead indications still in miles, but then who cares? Which metric zealot has ever cared one jot about the inconvenience of his/her [put that in for the new Equality and Human Rights Commission] pet scheme?

The next phase is to metricate all speed limit signs, provisionally set for a date early next year. This will be great fun, as armies of thousands of workmen go out over a 24-hour period to do a lightning change of road signs, at massive cost to the Irish economy - millions of, er, euros. Plus the cost of a public education campaign to make sure people don't drive at 80mph when they see an '80' sign'.

The Irish could have chosen, say, to invest in housing for poorer-off people, or improve services for the disabled, or develop their infrastructure.

No. Extermination of the system of imperial measurements, so detested by metric zealots, comes first, like it or not.

There's democracy for you!

So Ireland need to get a seperate production line for cars than UK (for its 3 million people)?

Sounds like good financial sence! (irony, folks).

ANYWAY - hasn't anyone realised that UK speedos (for the 58m people) have km/h as an "also ran" on the dials?

Its tiny, in a shaded coloured font and gets covered by the pointer. Try it - try noting your speed in km/h as you drive.

Actually don't! It's dangerous!

SteveH wrote

<<
So Ireland need to get a seperate production line for cars than UK (for its 3 million people)?
>>

They won't need a separate production line. In many cases the cars have been bought by dealers before they are actually manuafactured. It is standard practice for all the special parts (eg parts of a particular colour, trim etc) for a particular car to be sent to the assembly point for a specific vehicle. It is therefore little extra work to use a km/h speedo for purchasers in Dublin and a mph speedo for purchasers in London. If a special speedo cable is required for rught-hand drive cars with km/h speedo's, no extra work is required - these are already available for the South African/Australian markets.

Now, it the UK were to go metric, then the manufacturer would only need one model of speedo.

<<<REPLY: You can watch this amazing process actually happening in the Irish Republic at the moment. What a mess! And what cost!>>>

Indeed it is costly, but in the long-run will prove cost effective. It is a one-off cost. If only the UK could be as forward thinking.. As has been said already, it WILL happen eventually, so every time a new sign goes up in imperial it is a waste. Why not follow Irelands example and make new signs in metric?

<<<The first phase of metrication was to convert distances in miles on road signs to metric road distances on all the main roads. All the minor roads were left in miles. Result: drive from A to B along Irish roads and the distance keeps on going up and down like a yo yo! Most amusing! >>>

It was indeed bizarre using km for distance and mph for speed. This situation clearly could not go on for ever.

<<<Regulations now require car speedos in Ireland to lead in kilometres, with miles per hour as secondary.>>>

I would have thought it would make more sense to do away with the miles altogether. I agree with Steves comments (theres a first time for everything) regarding the dangers of looking at the second scale.

<<< It'll be a headache for all those with lead indications still in miles, but then who cares? >>>

I think you'll find that very few people care. It is a minor inconvenience.













SteveH

Re: Speedometers & Metric speed limits November 10 2003, 3:29 PM

So Ireland need to get a seperate production line for cars than UK (for its 3 million people)?

Sounds like good financial sence! (irony, folks).

ANYWAY - hasn't anyone realised that UK speedos (for the 58m people) have km/h as an "also ran" on the dials?

Its tiny, in a shaded coloured font and gets covered by the pointer. Try it - try noting your speed in km/h as you drive.

Actually don't! It's dangerous!

er. not sure what happened at the bottom of my message...

re (Andy): "Indeed it is costly, but in the long-run will prove cost effective".

REPLY: Please spell out in as much detail as you are able to what will be the savings arising out of spending millions of euros on unnecessarily converting tens of thousands of road signs which everyone understands at the moment.

Remember to include the 'opportunity cost' of this exercise i.e. the continuing losses that will arise out of the failure to use this money for other purposes like: investing in new port facilities, improving teacher-pupil ratios, buying life-saving equipment for hospitals, pump-priming new small businesses etc. etc.

I would bet that the majority of British drivers who see km/h speed limit signs regularly end up doing exactly what I do when driving through France. I see a "50" sign and my brain doesn't really take that in as 50 km/h. It just automatically recognizes a 30 mph limit. I see "80" and my brain just reads that as 50 mph.

Tony Bennett: "Result: drive from A to B along Irish roads and the distance keeps on going up and down like a yo yo! Most amusing!"

I know what you mean. I was over there in 1998 and it was almost like a guessing game as to whether the next sign would be miles or km.

"Rgulations now require car speedos in Ireland to be in kilometres, with miles per hour as secondary. It'll be a headache for all those with lead indications still in miles, but then who cares?"

I *hope* that the regulations only require km as the dominant indication for new cars. To require all existing speedos to be changed would be an intolerable imposition.

This is part of my concern. To many vintage and veteran car owners trying to obtain a km/h speedo would be: (a) very difficult or next to impossible, and (b) completely spoil the authenticity of the dash.

<<<re (Andy): "Indeed it is costly, but in the long-run will prove cost effective".

REPLY: Please spell out in as much detail as you are able to what will be the savings arising out of spending millions of euros on unnecessarily converting tens of thousands of road signs which everyone understands at the moment.>>>

On its own, the changing of road signs to metric does not bring the immediate financial and economic benefits that are obvious in other areas of metrication, but it is a one-off cost. Once it is done, thats it - The benefits however small per year, will continue forever.

Even if I concede that on its own, metrication of road signs has greater short-term costs than benefits, it is an essential part of the whole metrication process, which brings huge economic and financial benefits. These savings will easily cover the cost within a few years. And for the schools and hospitals you mention, metrication also has obvious long-term benefits. Again, the benefits last FOREVER, you have to look longer-term.

You describe the change of speed signs as 'unnecessary' Do you really think it would be acceptable to keep speed limit signs in mph indefinately when distance signs are already in km?

Like it or not, most people on both sides seem to agree that the change is inevitable so, clearly the sooner it is done, the sooner the benefits will start to be realised. The continued dragging of feet is costing us.

<<<I would bet that the majority of British drivers who see km/h speed limit signs regularly end up doing exactly what I do when driving through France. I see a "50" sign and my brain doesn't really take that in as 50 km/h. It just automatically recognizes a 30 mph limit. I see "80" and my brain just reads that as 50 mph.>>>

Indeed. Another good argument for using the same system.

As long as your car speedo has the same units as the road signs it is all very simple. I was in Australia a few years back and soon got used to kilometres because that was the only units on the speedo and on the road signs. Now I'm back in the UK I use miles and mph because thats whats on the speedo and signs.

It really doens't take long to adapt!

"Like it or not, most people on both sides seem to agree that the change is inevitable so, clearly the sooner it is done, the sooner the benefits will start to be realised. The continued dragging of feet is costing us"

30 yrs down the line and we still don't have metric roadsigns.

In america it is legal to have metric road signs - they tried it and it flopped.

In the UK it is illegal to have metric roadsigns - and there are less and less day by day.

This "inevitability" is on a par with the sun extinguishing!

"The continued dragging of feet is costing us"

I thought you already agreed that replacing mph with kmh and m with (erm) km does not net the UK any extra money?!?!?

Think if the cost of coverting ireland's small road network with our massive one.

It won't happen.

No govt will halt spending on the NHS or road improvement just to make signs say different numbers that we might get used to! They'll be out of office before you say "EU".

Indeed all those brand new roads and road speed systems are in shiny imperial round measures!

Actually - think about it - the bl**dy expensive M25 speed regulator signs only accomodate 2 digits - will they use "99" for 60 or something?

Don't make me laugh.

Unfortunately we'll still be arguing about this "inevitability" when we ask our grandsons to post for us!

<<<This "inevitability" is on a par with the sun extinguishing!>>>

The sun will extinguish eventually, just as we will be metric eventually. At the rate we're going, I'm not sure what will happen first.

<<<"The continued dragging of feet is costing us"

I thought you already agreed that replacing mph with kmh and m with (erm) km does not net the UK any extra money?!?!?>>>

I said the road signs IN ITSELF might not have financial benefits. In most other areas of trade, industry, education etc there is a significant cost by not completing the change to metric. And you cannot go completely metric unless the road signs are changed!

<<<Think if the cost of coverting ireland's small road network with our massive one.>>>

I agree, it is a massive operation. It should have been done a long time ago.

<<<It won't happen.>>>

might not be for 10 years, 50 years or 100 years, even 1000 years but...

IT WILL HAPPEN

<<<Indeed all those brand new roads and road speed systems are in shiny imperial round measures!>>>

a waste of money because they will eventually be replaced.

<<<Don't make me laugh.>>>

You won't be when the inevitable happens.

I wonder why it is the "inevitability" that winds you up most?

"I wonder why it is the "inevitability" that winds you up most?"

That's easy to answer.

Because I am on the "side" that is arguing that something that hasn't happened yet won't happen but is being argued by "the other side" to the fact that it will happen.

Do you realise how difficult it is to prove that something that hasn't happened yet will not happen - while it's not happening?

And how weird it is to see my own argument playing true (or "winning") in the present but having to defend the same argument on a hypothetical future that hasn't happened?

Hence why this "inevitability" is frustrating to argue (I'm not actually wound up - since without these arguments I wouldn't be posting my stuff here!)

I hope you recognise my little dilemma!

"The sun will extinguish eventually, just as we will be metric eventually. At the rate we're going, I'm not sure what will happen first."

LOL, I liked that one!

As for cost, what exactly is difficult about phasing new signs in as old ones are removed?

We could start doing that immediately and, if properly planned so as not to result in the Ireland situation, it would work well.

That'll be like phasing in a new voltage (say 400v)!

One by one each house will be "phased in".

Don't like it! Imagine the cost in lightbulbs alone!

SteveH wrote

<<
That'll be like phasing in a new voltage (say 400v)!

One by one each house will be "phased in".

Don't like it! Imagine the cost in lightbulbs alone!
>>

I think that Steve is getting things out of proporiton. The disruption caused by phasing in a new voltage (say 400V), or 110V would be comparable to the disruption that would be caused by Britain changing over to driving on the right. The disruption caused by metrication would be infinitesmal compared to either of the other two changes.

so having some signs say "50" for one system and others say "50" for another you do not see an inherant risk?

One easy solution is as follows:

Month 1 - Convert 70mph to 120km/h; 60mph to 100km/h and 50mph to 80km/h

Month 2 - Allow motorists to take a breather. (There are no signs with "50", "60" or "70"!)

Month 3 - Convert 40mph to 60km/h (or whatever is decided); Convert 30mph to 50km/h.

Month 4 - Allow motorists to take a breather. (There are no signs with "30" or "40".

Month 5 - Convert 20mph signs to 30km/h.

Note - During the conversion period all metric speed limit signs will have a yellow bar just below the numbers containing the text "km/h". After month 12 these yellow bars will be removed.


The plan in the 1970's was to have dual speed limit signs (I was them in use in Mauritius in 1978).

re (Martin): "One easy solution is as follows:

Month 1 - Convert 70mph to 120km/h; 60mph to 100km/h and 50mph to 80km/h

Month 2 - Allow motorists to take a breather. (There are no signs with "50", "60" or "70""


REPLY:

Ah yes. A certain section along the A12 and the A406 (North Circular Road) in north-eaat London would then have the following speed limits, in sequence:


40
80
40
80
100
40
80
40
80
40
80
100
80
40


Nice and simple!

Ah yes. A certain section along the A12 and the A406 (North Circular Road) in north-eaat London would then have the following speed limits, in sequence:

40
80km/h
40
80km/h
100km/h
40
80km/h
40
80km/h
40
80km/h
100km/h
80km/h
40


Nice and simple! - All right, the mph value could be placed on a supplementary sign below the main sign.

SteveH: "That'll be like phasing in a new voltage (say 400v)!

One by one each house will be "phased in".

Don't like it! Imagine the cost in lightbulbs alone!"

-----------------------------------------------------

Actually, that's not quite so crazy as it sounds, and you've picked a voltage (by chance, I suspect!) that already exists in the British network.

The 3-phase distribution used here has 415V available between phases. By running a second phase into each house, you could have both 240 and 415V available during the changeover period. If everything was eventually 415V, the neutral could then be dispensed with to remove the 240V option.

415V would be a dangerously high voltage for domestic use, but the same principle was actually used in parts of Europe to convert from 127 to 220 volts. A friend in Belgium tells me that in his area some 220V supplies are still provided as two phases of 127V.

OK, sorry for the technical digression.....

Steve,

There are two approaches to safety on domestic 230V supplies (now standardised across Europe). One is to tie one leg to earth at the supply end and to ensure that all fuses, switches etc are on the live leg. The advantage of this system is that when things go wrong, everything is earthed (unless it is the earth system that fails or something was installed incorrectly).

The other approach is to run each line at 115V relative to earth and to ensure that switches break both lines. The advantage of this is that if things go wrong, then at worst, a person will get a 115V shock which is far less likely to be fatal.

Either way there are risks and benefits. The UK has chosen to use the "earth one leg" approach.

No, I think the only safe way is the way the Irish are doing it.

Theres no problem with a gradual change of distance signs, but speed limits would have to be changed all in one go

Do you realise how difficult it is to prove that something that hasn't happened yet will not happen - while it's not happening?

Martin,

A 3-wire service (2 x 120V plus neutral) is standard in American homes. That provides 120V for lights and small appliances while allowing heavy appliances to run on 240V.

The 230V European standard, as it stands at present, is another complete fudge.

By the early 1970s British supplies were standardized at 240V with an allowable tolerance of +/-6%. The only way we've been able to go *officially* to 230V is by fiddling with the tolerances. Our official standard is now 230V, +10% / -6%.

In practical terms, our supplies are still really 240V +/-6% and likely to remain so for a long time.

err. not with you. what do you mean?

Steve - Ok I think I get your point now

You think that the speed limit signs in Ireland won't be changed?

Paul: "In practical terms, our supplies are still really 240V +/-6% and likely to remain so for a long time."

So ?

As long as I can use Continental appliances I really don't care.

PaulEOS wrote

<<
A 3-wire service (2 x 120V plus neutral) is standard in American homes. That provides 120V for lights and small appliances while allowing heavy appliances to run on 240V.
>>

Paul, am I correct in assuming then that the two "live" lines in the US are 180 degrees out of phase with each other, while in Belgium they are 120degrees out of phase. (using SteveH's figures of 127V and 220V, I noticed that 127*sqrt(3) is approx 220).

"Steve - Ok I think I get your point now

You think that the speed limit signs in Ireland won't be changed?"

Not quite.
I *think* the speed limits in Ireland won't change (about 60/40)

I *know* the UK ones won't (in my non-existant offspring's lifetime) (about 95/5) .


All this talk about voltage?

I've used the same appliances all over the world, from Andorra to America - and guess what?

I've plugged 'em in and they've all worked.

Get with the plan, lads, all todays stuff work from 110-250 *without* the flick of a switch!



There's my two-pence!

<<<I *think* the speed limits in Ireland won't change (about 60/40)>>>

well it all sounds pretty definate to me, we'll wait and see what happens next year..

<<<I *know* the UK ones won't (in my non-existant offspring's lifetime) (about 95/5) .>>>

You don't *know* neither do I
I agree that it is unlikely to happen for a long time. Hope we're both wrong.

"Paul, am I correct in assuming then that the two "live" lines in the US are 180 degrees out of phase with each other, while in Belgium they are 120degrees out of phase."

That's correct. The U.S. residential supply is single-phase from a center-tapped transformer, the mid-point being grounded (earthed) and used as the neutral. Three-phase is generally restricted to commercial use in America, whereas in Europe most distribution is 3-ph and in many areas houses take a full 3-phase supply.

The 120-degree angle between phases always results in the phase-to-phase voltage being SQRT(3) x phase-to-neutral voltage.

Thus in Europe we have systems running at 127/220, 220/380, 230/400, and 240/415V. The U.S. uses 120/208 and 277/480. Canada has 347/600V as well.

You're welcome to e-mail me if you're interested any further and I'll let you have a more detailed explanation.

Steve,
What you said about just plugging in and running on anything from 110 to 250V is true for some of the latest equipment which uses a type of power supply known as "switched mode" (typically in new TVs, rechargeable shavers, etc.)

You can't just do that for hair dryers, electric kettles, and most older equipment.

None of which relates to speed limit signs -- Sorry!

"I *think* the speed limits in Ireland won't change (about 60/40)"

I think you'll be wrong, the delays will end in the not to distant future.

"I *know* the UK ones won't (in my non-existant offspring's lifetime) (about 95/5)."

Very good odds indeed, I'd like to place a bet at your shop!

I think the move to metrication of UK road signs will begin within ten years.

"I think the move to metrication of UK road signs will begin within ten years."

That's exactly what Tony has been predicting for years.

Another 5,256,000 minutes to go... ;-)

Re: Speedometers & Metric speed limits November 12 2003, 1:27 PM

Martin,

A 3-wire service (2 x 120V plus neutral) is standard in American homes. That provides 120V for lights and small appliances while allowing heavy appliances to run on 240V.

The 230V European standard, as it stands at present, is another complete fudge.

>>>> How is the European single phase voltage of 230 V a fudge? The European system is superior to the American system for reasons of economy.

1.) The 230 V single phase can be derived from 400 V three phase without the use of costly transformers. All one does is tap off of one line and the neutral. In some countries the 400/230 V system is even available in homes. Heavy duty devices run off of the 3 phase and light duty devices run off of the single phase. How many US homes are wired for 3 phase?

2.) The higher voltage used allows for smaller currents and thus less I^2R losses in the conductors. It also allows for the use of smaller conductor to save on the copper cost.

In order to reduce the losses associated with using 120 V, South Korea switched their entire electrical grid in the early 1990s from 120 V to 230 V. They had to change their outlets from the US style to the Schucko style too.



By the early 1970s British supplies were standardized at 240V with an allowable tolerance of +/-6%. The only way we've been able to go *officially* to 230V is by fiddling with the tolerances. Our official standard is now 230V, +10% / -6%.

In practical terms, our supplies are still really 240V +/-6% and likely to remain so for a long time.


PaulEOS

Re: Speedometers & Metric speed limits November 12 2003, 4:39 PM


Thus in Europe we have systems running at 127/220, 220/380, 230/400, and 240/415V. The U.S. uses 120/208 and 277/480. Canada has 347/600V as well.

>>>>> For most uses of electricity, the difference between 220 V and 240 V is insignificant. Most products are designed to operate in a range of voltage then at a fixed voltage. The voltages stated are NOMINAL. One has to consider line loss and voltage drop that may reduce 125 V American service during a low peak time to 110 V during high peak and depending how far from the transformer or substation you are.

The standard for Europe is now 230/400 V. The old 220/380 is gone. In the same fashion the US may specify now a 120/480 V system, but there are still areas that have 110/440, 115/460, 117/470, 120/480, and even 500/125 V.

No Engineer who knows what he is doing worries about a 10 V variation on a 230 V nominal system.

Euric: ">>>> How is the European single phase voltage of 230 V a fudge?"

It's not the basic *system* that is a fudge, but the new official standard. For years in the U.K. we had 240V nominal, +/- 6%. Unless and until such time as transformers are replaced (which would be a very long process) it will remain so in technical terms.

Our adoption of the 230V "euro" standard is purely political. By changing the official specification to 230V with the odd, asymmetric tolerance of +10%/-6% we've been able to say "Hey look guys, Britain has been good and adopted the new 230V European standard."

Euric: "The 230 V single phase can be derived from 400 V three phase without the use of costly transformers. "

But you still need a transformer to step-down from the incoming high lines. It's a difference in approach: In built-up areas of Europe and the U.K. we tend to use one big transformer to feed many homes via a 3-ph network. By comparison, the U.S. uses a larger quantity of smaller transformers for residential areas, each tapped for only one phase.

The U.S. reduces I^2R losses by running HV for much of the distance involved, whereas we need larger conductors for the 230/400 (-ish) network. Don't forget too that although small appliances are 120V the 3-wire system means that when the load is reasonably balanced the system is performing effectively as 240V anyway -- The service neutral will carry only the difference current.

A comprehensive cost comparison between the methods would be interesting, though.

Euric: "The standard for Europe is now 230/400 V. The old 220/380 is gone."

Officially yes. In technical terms, it still exists in some European countries because they've just fudged the tolerances the same as Britain has done.

Euric: "110/440, 115/460, 117/470, 120/480, and even 500/125 V. "

Huh? A 110/440 system? Or are you referring to separate 110V single-ph and 440V delta?

Euric: "No Engineer who knows what he is doing worries about a 10 V variation on a 230 V nominal system"

No, but a 10% tolerance on 230V equates to 23V. If/when our tolerances are widened to 230V +/-10% as is proposed, that could make enough of a difference for equipment designed with 240 +/-6% in mind (i.e. minimum allowable voltage under our old standard 225.6V, under the new proposed standard 207V).

All of which is way off topic, except to demonstrate the political nature of the new standard.

Re: Speedometers & Metric speed limits December 12 2003, 11:20 AM

Euric: ">>>> How is the European single phase voltage of 230 V a fudge?"

It's not the basic *system* that is a fudge, but the new official standard. For years in the U.K. we had 240V nominal, +/- 6%. Unless and until such time as transformers are replaced (which would be a very long process) it will remain so in technical terms.

Our adoption of the 230V "euro" standard is purely political. By changing the official specification to 230V with the odd, asymmetric tolerance of +10%/-6% we've been able to say "Hey look guys, Britain has been good and adopted the new 230V European standard."

Reply:

As I said before, products are designed to work in a voltage range. Anything designed to run at 230 V will work fine at 220 V and at 240 V. There is nothing spectacular about everyone saying they are using 230 V. It just looks good on paper.

Even in the US, the the present system is suppose to be 120/480 V (120 V single phase and 480 V three phase industrial), these voltages still vary region to region. It is just nominally stated as 120 V and no one loses sleep over it.



Euric: "The 230 V single phase can be derived from 400 V three phase without the use of costly transformers. "

But you still need a transformer to step-down from the incoming high lines. It's a difference in approach: In built-up areas of Europe and the U.K. we tend to use one big transformer to feed many homes via a 3-ph network. By comparison, the U.S. uses a larger quantity of smaller transformers for residential areas, each tapped for only one phase.

Reply:

Of course. You transform voltage up when going over long distances to reduce the IČR losses and transform back down at the end destination. Even the
US does that. but in the US, 120 V is derived from 480 V using a transformer. In the countries using the 230/400 V system, the 230 V is derived from the 400 V without a transformer. Thus the savings in the cost of a transformer and in the power lost to heat while the transformer is operating.

The U.S. reduces I^2R losses by running HV for much of the distance involved, whereas we need larger conductors for the 230/400 (-ish) network. Don't forget too that although small appliances are 120V the 3-wire system means that when the load is reasonably balanced the system is performing effectively as 240V anyway -- The service neutral will carry only the difference current.

Neither the US 480 V service nor the European 400 V service run at long distances. They are derived by transformation within a 100 m or so distance of their final point of use.

In the US home, there is no guarantee that the loads will be balanced. Homes are arbitrarily wired and it is possible to have an unbalance. I've seen this happen when the neutral line is severed. The voltage on one side may drop to 30 V and on the otherside rise to over 200 V. This has damaged many an appliance.

A comprehensive cost comparison between the methods would be interesting, though.

Reply:

I'm sure the copper industry had played a role in the lower voltage standard for the US. More copper wire sales meant huge profits for the producers of copper.

Euric: "The standard for Europe is now 230/400 V. The old 220/380 is gone."

Officially yes. In technical terms, it still exists in some European countries because they've just fudged the tolerances the same as Britain has done.

Reply:

Yes, but it really doesn't matter. These numbers are nominal and allow for voltage swings.

Euric: "110/440, 115/460, 117/470, 120/480, and even 500/125 V. "

Huh? A 110/440 system? Or are you referring to separate 110V single-ph and 440V delta?

Reply:

Delta or wye. Three phase transformers in the US are wired primary wye and secondary delta. This allows for the portion of the winding nearest the core to be electrically neutral to prevent shock hazard if the winding should touch the core. Even single phase transformers are wired wye on the poles. Some older neighborhoods still have delta, but as the neighborhoods are rewired, the delta is changed to wye.

110/440 V means 120 V single phase and 440 V three phase. The nominal is now 120/480 V.

Euric: "No Engineer who knows what he is doing worries about a 10 V variation on a 230 V nominal system"

No, but a 10% tolerance on 230V equates to 23V. If/when our tolerances are widened to 230V +/-10% as is proposed, that could make enough of a difference for equipment designed with 240 +/-6% in mind (i.e. minimum allowable voltage under our old standard 225.6V, under the new proposed standard 207V).

All of which is way off topic, except to demonstrate the political nature of the new standard.


Reply:

Not so much political as economical.

Euric: "As I said before, products are designed to work in a voltage range. Anything designed to run at 230 V will work fine at 220 V and at 240 V."

True, but I was talking about the adjustment to allowable tolerances. Yes, something designed for 230V +/-10% will function perfectly well on a British 240V +/-6% supply.

But if our tolerance is widened to 230V +/-10% and at some point the utilities decide to take advantage of this new official standard and relax their regulation, a supply sitting at the bottom end of that tolerance could start to cause problems for something designed for 240V -6% minimum. I'm not saying this WILL happen, just that it's a possibility.

Euric: "There is nothing spectacular about everyone saying they are using 230 V. It just looks good on paper."

That was precisely my point. Equipment designed for 230V +/-10% will run on 240V +/-6% with no problem. So why the change in our official standard? It's just a political/diplomatic exercise. The only technical effect is if the utilities decide to take advantage of that change, as described above.

Euric: "but in the US, 120 V is derived from 480 V using a transformer. In the countries using the 230/400 V system, the 230 V is derived from the 400 V without a transformer. Thus the savings in the cost of a transformer and in the power lost to heat while the transformer is operating."

I assume you are referring to a commercial building with both 480 and 120 systems. In that case, I accept your point about the extra transformer.

But as far a residential is concerned, there is no 480V level involved -- The pole xfmr converts straight from the HV primary to 120/240V.

Euric: "In the US home, there is no guarantee that the loads will be balanced. Homes are arbitrarily wired and it is possible to have an unbalance."

Accepted.

How come "euric" argues coherently and naturally when it comes to electronics and engineering but stoops to mass insults and daft and ridiculous ideas when it comes to the economy or measurements.

Could it be because he *actually knows* what he is talking about with electronics and engineering?

Hmmmm....

Strange way to have an opinion on something one has no expert knowledge on!