We have touched this subject before, but as the threads are so long I've started a new.

The European voltage is often referred to as 230 +/10%. Simple enough, right? Wrong. In reality there is a European standard, EN 50160 for how the voltage is to be measured.

The requirements is +/-10% for at least 95% of the time. The remaining 5% of the time, it's +10/-15%. (253-195.5V)

Wait, it gets worse. You can't just take the instant readings, as dips and surges sends the voltage outside the interval. As these doesn't harm the appliances an average over time is taken. This would have been fine, had it not been for the fact that the standard calls for a 10 minute average. A miswiring can send 400V to the users, but as long as the problem is fixed within a minute or so the voltage is still within specifications.

Would you be surprised to know that it is the utilities who are behind this standard?

We should also not forget that there is a voltage drop in the installation (3-5%). Hence, in a worst case situation the voltage at the outlet can be 230V - 20% = 184V...

Take rural Italy. I once measured 185V at an outlet. Lights were noticeably dim when any other appliances were on. These guys had a long, stoneaged 220V overhead line (just 2 thin bare wires on wooden poles, porcelaine or like insulators)
A beautiful view, but technically rather outdated.

C-H,
Hang on a minute, mate,
For any sort of Voltage Drop measurement,
there needs to be a standard point from which these measurements are taken, does
EN 50160 give a standard point, at which these measurements should be taken.
I have done thousands of these measurements,
especially where motors are concerned, as with the inverse-square law applying, you can burn a motor out by low voltage.
Also, I disagree, with the use of the 10 minute period, used for voltage drop.
I have used a Data Logger and associated software for the last 2-3 years, to give a full chart of what has happened in the last 24-36 Hrs.

I don't have the EN 50160 myself. I have only seen a summary in Norwiegan.

I'm under the impression that New Zealand takes voltage regulation very seriously?

The voltage drop I was referring to was that within the installation (i.e. not the suppliers responsibility). It should be measured from the same point in Europe as in New Zealand. It is addressed in the Swedish wiring regulations, but it isn't very specific.

Kent might have better info.


Advice: In normal use it is recommended that equipment is fed with a voltage no lower than the equipment is intended for.

Normally the voltage drop in the installation should not exceed 4% of the nominal voltage.
----

I wonder if it is possible to write something less specific?

A drop of 4% in the installation (from service entrance to farthest point of utilization under normal load) is also the maximum permitted by IEE Regs. in Britain.

Years ago the maximum permitted drop was specified as 2.5% plus 1V.

>2.5% plus 1V

Why? Just to make something simple complex?

I don't know. I've often wondered why they came up with such an awkward specification.

It's there in the 13th and 14th editions (1955, 1966) of the IEE Regs., and in the revised metric 14th edition (1970), but the 4% tolerance is specified in the 15th (1981) edition. It may have actually changed during the seventies as an amendment to the 14th ed.

Just dug out my copy of 14th edition IEE Regs (1976 edition). It states in B23 that voltage drop from the consumer's terminals to any point in the installation should not exceed 2.5% of the declared nominal voltage, ie. 6V drop for a 240V supply. There is no mention of 2.5% plus 1V in the 1976 edition.
15th Edition 1981, also has voltage drop as 2.5%, and I clearly remember using this value when I was in college in the early 80's.
The change to 4% voltage drop appears to have been made in the 16th Edition in 1991, this is the 1st reference I can find in the Editions that I own.
Reading this topic I can see that the UK has some of the tightest voltage tolerances in the world. When loop testing I normally see voltages between 235 to 245V.

I beg your pardon -- I never kept my 1981 edition so I was working from memory on that one. Dang memory obviously letting me down!

My 14th edition is the one actually published in 1970, so it looks as though they dropped the 1V part somewhere along the way.

C-H,
Voltage Drop, is not really taken that seriously over here.
I normally only use the Data Logger, for Fault-finding purposes, where there is a
serious drop in voltage, and further more,
this really only occurs in Commercial/Industrial installations, I think that I have only used the DLogger, in a domestic situation once, by memory.
It's just handy to see what is happening to the Voltage(especially 3phase), over a longer period of time.