230V/240V Question

[PBC_1966]

If you want there to be a harmonised supply, with everybody having the same V±x range, in order that you may have a single market for appliances then everybody has to have a harmonised supply with the same V±x range.

No they don't, if the existing supply specification falls within the proposed range for appliances. Although we haven't even talked about voltage drop limits within the installation yet.

That was the whole point of it. The thing you describe as "other than" is exactly what it was for!

Which is exactly what I said at the start: It was changed only in order to claim compliance with a new 230V European standard for nominal voltage.

The 24-hour clock is something which all sensible people use already, particularly where it is important to avoid ambiguity, e.g. transportation timetables. For some reason, though, the 24-hour clock is something which the USA seems to struggle to understand.

There's nothing ambiguous about using 12-hour times with a.m. & p.m. suffixes, or with something else which indicates the same (e.g. the common convention on bus & train schedules here of having p.m. times in bold type). You could argue that it might leave room for more mistakes to be made if somebody isn't paying attention, but it's not ambiguous.

 

[ban-all-sheds]

Which is exactly what I said at the start: It was changed only in order to claim compliance with a new 230V European standard for nominal voltage.

I despair.

That was the whole point. It was done to CREATE a new 230V European standard for nominal voltage.

There's nothing ambiguous about using 12-hour times with a.m. & p.m. suffixes, or with something else which indicates the same (e.g. the common convention on bus & train schedules here of having p.m. times in bold type). You could argue that it might leave room for more mistakes to be made if somebody isn't paying attention, but it's not ambiguous.

As I said - understanding the concept of the 24-hour clock is something which most people in the USA struggle to do.

 

[PBC_1966]

That was the whole point. It was done to CREATE a new 230V European standard for nominal voltage.

As I also said earlier, whether done after the fact or done as part of the creation of the European standard, it was still a change solely to comply with that standard and for no practical reason,

 

[EFLImpudence]

Didn't you previously say it was for no technical reason? It was for a practical reason.


We could have adopted the Euro when introduced.

For your and Winston's benefit we could have called it a 69 pence coin.

 

[JohnW2]

Didn't you previously say it was for no technical reason? It was for a practical reason.

I thought that most people agreed that the current 'on paper harmonisation' really achieves nothing useful, and that it only has a useful/practical purpose if it is perceived as a prelude to long-term gradual changes (unlikely to be completed within any of our lifetimes) in the direction of getting the actual supplied voltages closer to one another, ultimately with the 'average' supply voltage being the same, in all the countries concerned?

Kind Regards, John

 

[stillp]

The practical reason is that manufacturers can now use the same nominal voltage and tolerances whichever European country their products are intended to be used in.

 

[winston1]

The practical reason is that manufacturers can now use the same nominal voltage and tolerances whichever European country their products are intended to be used in.

Just not true. Lots of things just do not work properly over the range 216.2 to 253 volts. Incandescent lamps for instance, especially the halogen types so popular now for "torches" in the ceiling.

 

[ban-all-sheds]

As I also said earlier, whether done after the fact or done as part of the creation of the European standard, it was still a change solely to comply with that standard and for no practical reason,

It was done for a very practical reason - it was done to create a new 230V European standard for nominal voltage.

 

[JohnW2]

The practical reason is that manufacturers can now use the same nominal voltage and tolerances whichever European country their products are intended to be used in.

I don't really understand what that actually means. In order to achieve what you say, what matters is the range of permitted voltages across all the countries (i.e. 216.2V - 253V). The numerical value of the 'nominal' voltage is arbitrary and, particularly when (as is the case) the range is asymmetrical about that 'nominal' figure, the value of that nominal voltage is simply arbitrary and totally irrelevant. The 'nominal' voltage could have been specified as being anything between 216.2V and 253V and, with appropriate associated tolerances, would have exactly the same meaning - to manufacturers of products or anyone else.

Furthermore, specifying the tolerances (of permitted deviations from the arbitrary 'nominal') as percentages merely means that people have to do arithmetic to work out what they actually mean (in terms of permitted voltages) - use of percentages would only make any sense if the 'nominal' voltage itself could vary.

If a suitable garment, toy or whatever were deemed to be suitable for children aged 2-5 years, that range is what matters. Nothing would be gained (or altered, or made any easier/simpler) by specifying a 'nominal' suitable age of, say 2.5, 3.5 or 4.5 years with an accompanying appropriate 'tolerance (i.e. 2.5 -0.5+2.5, 3.5 +/-1.5 etc.). Nor would it be particularly sensible (or helpful, to anyone) to declare a 'nominal' suitable age of 2.5 or 4.5 years if the product were deemed suitable for 2-5 year olds.

Kind Regards, John

 

[EFLImpudence]

I really don't see the difficulty in understanding.

When I post the dictionary definition of 'nominal', you reply "Yes, we know that" but then go on to disregard that definition and state it is arbitrary and irrelevant.
It is not arbitrary; it is the same as Europe.
It is not irrelevant; it is the value used for calculations.
It is the actual voltage (within the limits) on the day which is irrelevant.

How could you have a varying nominal voltage?

 

[JohnW2]

It was done for a very practical reason - it was done to create a new 230V European standard for nominal voltage.

If you mean that it was done with the intention that all European countries would, as a consequence, gradually move to actually providing a supply of average voltage 230V, then that would make sense.

If you mean something else, I would welcome an explanation, since I struggle to see any other point. Very many products have been labelled (and presumably designed for) "220V-240V" or "220V-250V" for decades, and that seems the obvious way to specify appropriate voltage ranges for products (and supplies). To arbitrarily declare some figure within that range as being the 'nominal' voltage would appear to achieve absolutely nothing, per se.

If a 'standard loaf' were required to have a weight between 0.7 kg and 1.3 kg, it would make no difference to anyone whether it were described as having a 'nominal weight' of 0.7, 0.8, 1.0, 1.2 or 1.3 kg, provided enough additional information were provided to allow one to determine the minimum and maximum permitted weights.

Kind Regards, John

 

[JohnW2]

I really don't see the difficulty in understanding. When I post the dictionary definition of 'nominal', you reply "Yes, we know that" but then go on to disregard that definition and state it is arbitrary and irrelevant.

I think you should probably be looking in some 'technical dictionary' or suchlike, rather than a general dictionary. In virtually any other situation in any engineering field I can think of (mechanical, electrical, chemical etc.), as well as in various regulations and legislation about product labelling etc., a specified 'nominal' value indicates the 'average' or 'intended' value of some measurement, usually with a specified tolerance around that nominal value. I can think of no other situation in which (as with UK supply voltage) the 'nominal' value of something differs appreciably from a very high proportion of real-world measurements (and the average thereof) of that something. That is simply not the sense in which 'nominal' is normally used in engineering circles.

It is not arbitrary; it is the same as Europe.

It is arbitrarily the same throughout Europe.

It is not irrelevant; it is the value used for calculations.

.. and therein lies a problem, and a danger, which has only just been (partially) recognised by BS7671. Amd3 at last recognises that using the 'nominal' voltage for calculating the minimum 'safe' Zs for final circuits can result in an 'unsafe' situation if the supply voltage is less than that 'nominal figure' - what matters for such calculations is the lowest possible supply voltage. Apparently because of external factors, JPEL/64 did not require the calculations to be undertaken for a supply voltage of 216.2V - but by effectively requiring calculations at 218.5V they got pretty close.

It is the actual voltage (within the limits) on the day which is irrelevant.

For 'safe' calculations, the actual voltage on the day is, indeed, irrelevant, and some arbitrarily chosen 'nominal voltage' (which could be miles away from any voltage ever seen by the installation in question) is even more irrelevant. What matters is the minimum or maximum 'possible' ('permitted') supply voltage - minimum for some calculations, maximum for others.

How could you have a varying nominal voltage?

In the context we're talking about, one couldn't - which is why it makes no sense to quote the 'tolerance' as a percentage. In other situations, one might have, say, a range of screws (or whatever) with nominal diameters of 3, 4, 6, 8, 10 mm etc.. In that case, it could well make sense to state an acceptable tolerance (for any size) of ±2%, rather than having to quote indiviual absolute tolerances for each and every size.

Kind Regards, John

 

[winston1]

[QUOTE="EFLImpudence, post: 3543053, member: 144975"
It is not arbitrary; it is the same as Europe.
[/QUOTE]

Don't think that is the case. The tolerances are different in Europe.

 

[ban-all-sheds]

Lots of things just do not work properly over the range 216.2 to 253 volts. Incandescent lamps for instance, especially the halogen types so popular now for "torches" in the ceiling.

ELV ones are fine, as their electronic transformers manage the LV variation.

 

[ban-all-sheds]

If a suitable garment, toy or whatever were deemed to be suitable for children aged 2-5 years, that range is what matters. Nothing would be gained (or altered, or made any easier/simpler) by specifying a 'nominal' suitable age of, say 2.5, 3.5 or 4.5 years with an accompanying appropriate 'tolerance (i.e. 2.5 -0.5+2.5, 3.5 +/-1.5 etc.)

A great deal would be gained if such children were officially labelled Stage 2 Children, but in some countries that meant 2-4, and in others 3-5. It would mean that once the age range was harmonised there would be a single market for the toys etc.